Littérature scientifique sur le sujet « Plant traits (PTs) »
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Articles de revues sur le sujet "Plant traits (PTs)"
1
Liu, Xiaoman, Xiaolei Zhao, Lijun Zhang, Wenjing Lu, Xiaojuan Li et Kai Xiao. « TaPht1;4, a high-affinity phosphate transporter gene in wheat (Triticum aestivum), plays an important role in plant phosphate acquisition under phosphorus deprivation ». Functional Plant Biology 40, no 4 (2013) : 329. http://dx.doi.org/10.1071/fp12242.
Texte intégralRésumé :
An expressed sequence tag (EST) highly similar to BdPT1–4, a phosphate transporter (PT) gene in Brachypodium distachyon, was obtained in a wheat root cDNA subtractive suppression library containing genes that respond to low-phosphate (Pi) stress. The DNA sequence covering this EST (designated as TaPht1;4) was determined based on screening a wheat DNA library. TaPht1;4 consists of two exons and one intron and encodes a 555 amino acid (aa) polypeptide with a molecular weight of 60.85 kDa and an isoelectric point of 7.60. TaPht1;4 contains 12 conserved membrane-spanning domains similar to previously reported PTs in diverse plant species. Yeast complement analysis in low-Pi medium confirmed that TaPht1;4 confers the capacity to uptake Pi to MB192, a yeast strain with a defective high-affinity PT; with an apparent Km of 35.3 μM. The TaPht1;4 transcripts were specifically detected in the root and were highly induced under Pi deficiency. TaPht1;4 was also expressed following a diurnal pattern, i.e. high levels during daytime and low levels during night-time. TaPht1;4 overexpression and downregulation dramatically altered the plant phenotypic features under low-Pi conditions. Samples that overexpressed TaPht1;4 had significantly improved growth traits and accumulated more Pi than the wild-type plant and those with downregulated TaPht1;4 expression. Therefore, TaPht1;4 is a high-affinity PT gene that plays a critical role in wheat Pi acquisition under Pi deprivation.
2
Koven, Charles D., Ryan G. Knox, Rosie A. Fisher, Jeffrey Q. Chambers, Bradley O. Christoffersen, Stuart J. Davies, Matteo Detto et al. « Benchmarking and parameter sensitivity of physiological and vegetation dynamics using the Functionally Assembled Terrestrial Ecosystem Simulator (FATES) at Barro Colorado Island, Panama ». Biogeosciences 17, no 11 (15 juin 2020) : 3017–44. http://dx.doi.org/10.5194/bg-17-3017-2020.
Texte intégralRésumé :
Abstract. Plant functional traits determine vegetation responses to environmental variation, but variation in trait values is large, even within a single site. Likewise, uncertainty in how these traits map to Earth system feedbacks is large. We use a vegetation demographic model (VDM), the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to explore parameter sensitivity of model predictions, and comparison to observations, at a tropical forest site: Barro Colorado Island in Panama. We define a single 12-dimensional distribution of plant trait variation, derived primarily from observations in Panama, and define plant functional types (PFTs) as random draws from this distribution. We compare several model ensembles, where individual ensemble members vary only in the plant traits that define PFTs, and separate ensembles differ from each other based on either model structural assumptions or non-trait, ecosystem-level parameters, which include (a) the number of competing PFTs present in any simulation and (b) parameters that govern disturbance and height-based light competition. While single-PFT simulations are roughly consistent with observations of productivity at Barro Colorado Island, increasing the number of competing PFTs strongly shifts model predictions towards higher productivity and biomass forests. Different ecosystem variables show greater sensitivity than others to the number of competing PFTs, with the predictions that are most dominated by large trees, such as biomass, being the most sensitive. Changing disturbance and height-sorting parameters, i.e., the rules of competitive trait filtering, shifts regimes of dominance or coexistence between early- and late-successional PFTs in the model. Increases to the extent or severity of disturbance, or to the degree of determinism in height-based light competition, all act to shift the community towards early-successional PFTs. In turn, these shifts in competitive outcomes alter predictions of ecosystem states and fluxes, with more early-successional-dominated forests having lower biomass. It is thus crucial to differentiate between plant traits, which are under competitive pressure in VDMs, from those model parameters that are not and to better understand the relationships between these two types of model parameters to quantify sources of uncertainty in VDMs.
3
Verheijen, L. M., V. Brovkin, R. Aerts, G. Bönisch, J. H. C. Cornelissen, J. Kattge, P. B. Reich, I. J. Wright et P. M. van Bodegom. « Impacts of trait variation through observed trait-climate relationships on performance of a representative Earth System model : a conceptual analysis ». Biogeosciences Discussions 9, no 12 (19 décembre 2012) : 18907–50. http://dx.doi.org/10.5194/bgd-9-18907-2012.
Texte intégralRésumé :
Abstract. In current dynamic global vegetation models (DGVMs), including those incorporated into Earth System Models (ESMs), terrestrial vegetation is represented by a small number of plant functional types (PFTs), each with fixed properties irrespective of their predicted occurrence. This contrasts with natural vegetation, in which many plant traits vary systematically along geographic and environmental gradients. In the JSBACH DGVM, which is part of the MPI-ESM, we allowed three traits (specific leaf area (SLA), maximum carboxylation rate at 25 °C (Vcmax25) and maximum electron transport rate (Jmax25)) to vary within PFTs via trait-climate relationships based on a large trait database. For all three traits, the means of observed natural trait values strongly deviated from values used in the default model, with mean differences of 32.3% for Vcmax25, 26.8% for Jmax25 and 17.3% for SLA. Compared to the default simulation, allowing trait variation within PFTs resulted in GPP differences up to 50% in the tropics, in > 35% different dominant vegetation cover, and a closer match with a natural vegetation map. The discrepancy between default trait values and natural trait variation, combined with the substantial changes in simulated vegetation properties, together emphasize that incorporating observational data based on the ecological concepts of environmental filtering will improve the modeling of vegetation behavior in DGVMs and as such will enable more reliable projections in unknown climates.
4
Butler, Ethan E., Abhirup Datta, Habacuc Flores-Moreno, Ming Chen, Kirk R. Wythers, Farideh Fazayeli, Arindam Banerjee et al. « Mapping local and global variability in plant trait distributions ». Proceedings of the National Academy of Sciences 114, no 51 (1 décembre 2017) : E10937—E10946. http://dx.doi.org/10.1073/pnas.1708984114.
Texte intégralRésumé :
Our ability to understand and predict the response of ecosystems to a changing environment depends on quantifying vegetation functional diversity. However, representing this diversity at the global scale is challenging. Typically, in Earth system models, characterization of plant diversity has been limited to grouping related species into plant functional types (PFTs), with all trait variation in a PFT collapsed into a single mean value that is applied globally. Using the largest global plant trait database and state of the art Bayesian modeling, we created fine-grained global maps of plant trait distributions that can be applied to Earth system models. Focusing on a set of plant traits closely coupled to photosynthesis and foliar respiration—specific leaf area (SLA) and dry mass-based concentrations of leaf nitrogen (Nm) and phosphorus (Pm), we characterize how traits vary within and among over 50,000 ∼50×50-km cells across the entire vegetated land surface. We do this in several ways—without defining the PFT of each grid cell and using 4 or 14 PFTs; each model’s predictions are evaluated against out-of-sample data. This endeavor advances prior trait mapping by generating global maps that preserve variability across scales by using modern Bayesian spatial statistical modeling in combination with a database over three times larger than that in previous analyses. Our maps reveal that the most diverse grid cells possess trait variability close to the range of global PFT means.
5
Meng, T. T., H. Wang, S. P. Harrison, I. C. Prentice, J. Ni et G. Wang. « Responses of leaf traits to climatic gradients : adaptive variation vs. compositional shifts ». Biogeosciences Discussions 12, no 9 (13 mai 2015) : 7093–124. http://dx.doi.org/10.5194/bgd-12-7093-2015.
Texte intégralRésumé :
Abstract. Dynamic global vegetation models (DGVMs) typically rely on plant functional types (PFTs), which are assigned distinct environmental tolerances and replace one another progressively along environmental gradients. Fixed values of traits are assigned to each PFT; modelled trait variation along gradients is thus driven by PFT replacement. But empirical studies have revealed "universal" scaling relationships (quantitative trait variations with climate that are similar within and between species, PFTs and communities); and continuous, adaptive trait variation has been proposed to replace PFTs as the basis for next-generation DGVMs. Here we analyse quantitative leaf-trait variation on long temperature and moisture gradients in China with a view to understanding the relative importance of PFT replacement vs. continuous adaptive variation within PFTs. Leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC) and nitrogen content of dry matter were measured on all species at 80 sites ranging from temperate to tropical climates and from dense forests to deserts. Chlorophyll fluorescence traits and carbon, phosphorus and potassium contents were measured at 47 sites. Generalized linear models were used to relate log-transformed trait values to growing-season temperature and moisture indices, with or without PFT identity as a predictor, and to test for differences in trait responses among PFTs. Continuous trait variation was found to be ubiquitous. Responses to moisture availability were generally similar within and between PFTs, but biophysical traits (LA, SLA and LDMC) of forbs and grasses responded differently from woody plants. SLA and LDMC responses to temperature were dominated by the prevalence of evergreen PFTs with thick, dense leaves at the warm end of the gradient. Nutrient (N, P and K) responses to climate gradients were generally similar within all PFTs. Area-based nutrients generally declined with moisture; Narea and Karea declined with temperature, but Parea increased with temperature. Although the adaptive nature of many of these trait–climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must also take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits.
6
Meng, T. T., H. Wang, S. P. Harrison, I. C. Prentice, J. Ni et G. Wang. « Responses of leaf traits to climatic gradients : adaptive variation versus compositional shifts ». Biogeosciences 12, no 18 (17 septembre 2015) : 5339–52. http://dx.doi.org/10.5194/bg-12-5339-2015.
Texte intégralRésumé :
Abstract. Dynamic global vegetation models (DGVMs) typically rely on plant functional types (PFTs), which are assigned distinct environmental tolerances and replace one another progressively along environmental gradients. Fixed values of traits are assigned to each PFT; modelled trait variation along gradients is thus driven by PFT replacement. But empirical studies have revealed "universal" scaling relationships (quantitative trait variations with climate that are similar within and between species, PFTs and communities); and continuous, adaptive trait variation has been proposed to replace PFTs as the basis for next-generation DGVMs. Here we analyse quantitative leaf-trait variation on long temperature and moisture gradients in China with a view to understanding the relative importance of PFT replacement vs. continuous adaptive variation within PFTs. Leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC) and nitrogen content of dry matter were measured on all species at 80 sites ranging from temperate to tropical climates and from dense forests to deserts. Chlorophyll fluorescence traits and carbon, phosphorus and potassium contents were measured at 47 sites. Generalized linear models were used to relate log-transformed trait values to growing-season temperature and moisture indices, with or without PFT identity as a predictor, and to test for differences in trait responses among PFTs. Continuous trait variation was found to be ubiquitous. Responses to moisture availability were generally similar within and between PFTs, but biophysical traits (LA, SLA and LDMC) of forbs and grasses responded differently from woody plants. SLA and LDMC responses to temperature were dominated by the prevalence of evergreen PFTs with thick, dense leaves at the warm end of the gradient. Nutrient (N, P and K) responses to climate gradients were generally similar within all PFTs. Area-based nutrients generally declined with moisture; Narea and Karea declined with temperature, but Parea increased with temperature. Although the adaptive nature of many of these trait-climate relationships is understood qualitatively, a key challenge for modelling is to predict them quantitatively. Models must take into account that community-level responses to climatic gradients can be influenced by shifts in PFT composition, such as the replacement of deciduous by evergreen trees, which may run either parallel or counter to trait variation within PFTs. The importance of PFT shifts varies among traits, being important for biophysical traits but less so for physiological and chemical traits. Finally, models should take account of the diversity of trait values that is found in all sites and PFTs, representing the "pool" of variation that is locally available for the natural adaptation of ecosystem function to environmental change.
7
Verheijen, L. M., V. Brovkin, R. Aerts, G. Bönisch, J. H. C. Cornelissen, J. Kattge, P. B. Reich, I. J. Wright et P. M. van Bodegom. « Impacts of trait variation through observed trait–climate relationships on performance of an Earth system model : a conceptual analysis ». Biogeosciences 10, no 8 (15 août 2013) : 5497–515. http://dx.doi.org/10.5194/bg-10-5497-2013.
Texte intégralRésumé :
Abstract. In many current dynamic global vegetation models (DGVMs), including those incorporated into Earth system models (ESMs), terrestrial vegetation is represented by a small number of plant functional types (PFTs), each with fixed properties irrespective of their predicted occurrence. This contrasts with natural vegetation, in which many plant traits vary systematically along geographic and environmental gradients. In the JSBACH DGVM, which is part of the MPI-ESM, we allowed three traits (specific leaf area (SLA), maximum carboxylation rate at 25 °C (Vcmax25) and maximum electron transport rate at 25 °C (Jmax25)) to vary within PFTs via trait–climate relationships based on a large trait database. The R2adjusted of these relationships were up to 0.83 and 0.71 for Vcmax25 and Jmax25, respectively. For SLA, more variance remained unexplained, with a maximum R2adjusted of 0.40. Compared to the default simulation, allowing trait variation within PFTs resulted in gross primary productivity differences of up to 50% in the tropics, in > 35% different dominant vegetation cover, and a closer match with a natural vegetation map. The discrepancy between default trait values and natural trait variation, combined with the substantial changes in simulated vegetation properties, together emphasize that incorporating climate-driven trait variation, calibrated on observational data and based on ecological concepts, allows more variation in vegetation responses in DGVMs and as such is likely to enable more reliable projections in unknown climates.
8
Liu, Chun-Yan, Xiao-Niu Guo, Xiao-Long Wu, Feng-Jun Dai et Qiang-Sheng Wu. « The Comprehensive Effects of Rhizophagus intraradices and P on Root System Architecture and P Transportation in Citrus limon L. » Agriculture 12, no 3 (22 février 2022) : 317. http://dx.doi.org/10.3390/agriculture12030317.
Texte intégralRésumé :
Both arbuscular mycorrhizal fungi (AMF) and phosphorus (P) collectively influence the root system architecture (RSA), but whether the combination of the two affects RSA, particularly lateral root formation, is unknown. In the present study, a pot experiment was conducted to evaluate the effects of an arbuscular mycorrhizal fungus (Rhizophagus intraradices) on the RSA of lemon (Citrus limon L.) seedlings under 0 (P0) and 50 mg/kg (P50) P levels. Moreover, P and carbohydrate content; acid phosphatase activity; and the expression of P transporter genes (PTs), phosphatase genes (PAPs), and lateral-root-related genes; were determined. Our results show that root mycorrhizal colonization and mycorrhizal dependency of lemon plants are significantly higher under P0 than under P50 conditions. AMF significantly promoted the plant growth performance of lemon, irrespective of substrate P levels. The RSA parameters of AMF plants, including total root length, projected area, surface area, average diameter, volume, and second- and third-order lateral root numbers, were distinctly increased under the two P levels compared to those of non-AMF plants. Mycorrhizal treatment also induced higher carbohydrate (sucrose, glucose, and fructose) and P contents, along with a higher activity of root acid phosphatase. The expression of P-related genes, including ClPAP1, ClPT1, ClPT3, ClPT5, and ClPT7, as well as the expression of lateral-root-related genes (ClKRP6, ClPSK6, and ClRSI-1), was dramatically upregulated by AMF inoculation, irrespective of substrate P levels. Principal component analysis showed that root P and carbohydrate contents, as well as the expression of ClKRP6 and ClPSK6, were positively correlated with RSA traits and lateral root development. Our study demonstrates that mycorrhizas accelerate the P acquisition and carbohydrate accumulation of lemon plants by upregulating the expression of lateral-root-related genes, thereby positively improving the RSA. Furthermore, AMF had a greater impact on the RSA of lemon than substrate P levels.
9
Buotte, Polly C., Charles D. Koven, Chonggang Xu, Jacquelyn K. Shuman, Michael L. Goulden, Samuel Levis, Jessica Katz et al. « Capturing functional strategies and compositional dynamics in vegetation demographic models ». Biogeosciences 18, no 14 (30 juillet 2021) : 4473–90. http://dx.doi.org/10.5194/bg-18-4473-2021.
Texte intégralRésumé :
Abstract. Plant community composition influences carbon, water, and energy fluxes at regional to global scales. Vegetation demographic models (VDMs) allow investigation of the effects of changing climate and disturbance regimes on vegetation composition and fluxes. Such investigation requires that the models can accurately resolve these feedbacks to simulate realistic composition. Vegetation in VDMs is composed of plant functional types (PFTs), which are specified according to plant traits. Defining PFTs is challenging due to large variability in trait observations within and between plant types and a lack of understanding of model sensitivity to these traits. Here we present an approach for developing PFT parameterizations that are connected to the underlying ecological processes determining forest composition in the mixed-conifer forest of the Sierra Nevada of California, USA. We constrain multiple relative trait values between PFTs, as opposed to randomly sampling within the range of observations. An ensemble of PFT parameterizations are then filtered based on emergent forest properties meeting observation-based ecological criteria under alternate disturbance scenarios. A small ensemble of alternate PFT parameterizations is identified that produces plausible forest composition and demonstrates variability in response to disturbance frequency and regional environmental variation. Retaining multiple PFT parameterizations allows us to quantify the uncertainty in forest responses due to variability in trait observations. Vegetation composition is a key emergent outcome from VDMs and our methodology provides a foundation for robust PFT parameterization across ecosystems.
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Uddin, Md Shalim, Masum Billah, Rozina Afroz, Sajia Rahman, Nasrin Jahan, Md Golam Hossain, Shamim Ara Bagum et al. « Evaluation of 130 Eggplant (Solanum melongena L.) Genotypes for Future Breeding Program Based on Qualitative and Quantitative Traits, and Various Genetic Parameters ». Horticulturae 7, no 10 (8 octobre 2021) : 376. http://dx.doi.org/10.3390/horticulturae7100376.
Texte intégralRésumé :
Eggplant is an essential widespread year-round fruit vegetable. This study was conducted using 130 local germplasm of brinjal to select diverse parents based on the multiple traits selection index for the future breeding program. This selection was performed focusing on 14 qualitative and 10 quantitative traits variation and genetic parameters namely, phenotypic and genotypic variance (PV and GV) and genotypic and phenotypic coefficients of variation (GCV and PCV), broad-sense heritability (hBS), genetic advance, traits association, genotype by trait biplot (G × T), heatmap analysis and multi-trait index based on factor analysis and genotype-ideotype distance (MGIDI). Descriptive statistics and analysis of variance revealed a wide range of variability for morpho-physiological traits. Estimated hBS for all the measured traits ranged from 10.6% to 93%, indicating that all the traits were highly inheritable. Genetic variances were low to high for most morpho-physiological traits, indicating complex genetic architecture. Yield per plant was significantly correlated with fruit diameter, fruits per plant, percent fruits infestation by brinjal shoot and fruit borer, and fruit weight traits indicating that direct selection based on fruit number and fruit weight might be sufficient for improvement of other traits. The first two principal components (PCs) explained about 81.27% of the total variation among lines for 38 brinjal morpho-physiological traits. Genotype by trait (G × T) biplot revealed superior genotypes with combinations of favorable traits. The average genetic distance was 3.53, ranging from 0.25 to 20.01, indicating high levels of variability among the germplasm. The heat map was also used to know the relationship matrix among all the brinjal genotypes. MGIDI is an appropriate method of selection based on multiple trait information. Based on the fourteen qualitative and ten quantitative traits and evaluation of various genetic parameters, the germplasm G80, G54, G66, and G120 might be considered as best parents for the future breeding program for eggplant improvement.
Thèses sur le sujet "Plant traits (PTs)"
1
Imran, Hafiz Ali. « Remote Sensing Tools for Monitoring Grassland Plant Leaf Traits and Biodiversity ». Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/329592.
Texte intégralRésumé :
Grasslands are one of the most important ecosystems on Earth, covering approximately one-third of the Earth’s surface. Grassland biodiversity is important as many services provided by such ecosystems are crucial for the human economy and well-being. Given the importance of grasslands ecosystems, in recent years research has been carried out on the potential to monitor them with novel remote sensing techniques. Improved detectors technology and novel sensors providing fine-scale hyperspectral imagery have been enabling new methods to monitor plant traits (PTs) and biodiversity.
The aims of the work were to study different approaches to monitor key grassland PTs such as Leaf Area Index (LAI) and biodiversity-related traits. The thesis consists of 3 parts: 1) Evaluating the performance of remote sensing methods to estimate LAI in grassland ecosystems, 2) Estimating plant biodiversity by using the optical diversity approach in grassland ecosystems, and 3) Investigating the relationship between PTs variability with alpha and beta diversity for the applicability of the optical diversity approach in a subalpine grassland of the Italian Alps
To evaluate the performance of remote sensing methods to estimate LAI, temporal and spatial observations of hyperspectral reflectance and LAI were analyzed at a grassland site in Monte Bondone, Italy (IT-MBo). In 2018, ground temporal observations of hyperspectral reflectance and LAI were carried out at a grassland site in Neustift, Austria (AT-NEU). To estimate biodiversity, in 2018 and 2019 a floristics survey was conducted to determine species composition and hyperspectral data were acquired at two grassland sites: IT-MBo and University of Padova’s Experimental Farm, Legnaro, Padua, Italy (IT-PD) respectively. Furthermore, in 2018, biochemistry analysis of the biomass samples collected from the grassland site IT-MBo was carried out to determine the foliar biochemical PTs variability.
The results of the thesis demonstrated that the grassland spectral response across different spectral regions (Visible: VIS, red-edge: RE, Near-infrared: NIR) showed to be both site-specific and scale-dependent. In the first part of the thesis, the performance of spectral vegetation indices (SVIs) based on visible, red-edge (RE), and NIR bands alongside SVIs solely based or NIR-shoulder bands (wavelengths 750 - 900 nm) was evaluated. A strong correlation (R2 > 0.8) was observed between grassland LAI and both RE and NIR-shoulder SVIs on a temporal basis, but not on a spatial basis. Using the PROSAIL Radiative Transfer Model (RTM), it was demonstrated that grassland structural heterogeneity strongly affects the ability to retrieve LAI, with high uncertainties due to structural and biochemical PTs co-variation.
In the second part, the applicability of the spectral variability hypothesis (SVH) was questioned and highlighted the challenges to use high-resolution hyperspectral images to estimate biodiversity in complex grassland ecosystems. It was reported that the relationship between biodiversity (Shannon, Richness, Simpson, and Evenness) and optical diversity metrics (Coefficient of variation (CV) and Standard deviation (SD)) is not consistent across plant communities. The results of the second part suggested that biodiversity in terms of species richness could be estimated by optical diversity metrics with an R2 = 0.4 at the IT-PD site where the grassland plots were artificially established and are showing a lower structure and complexity from the natural grassland plant communities. On the other hand, in the natural ecosystems at IT-MBo, it was more difficult to estimate biodiversity indices, probably due to structural and biochemical PTs co-variation. The effects of canopy non-vegetative elements (flowers and dead material), shadow pixels, and overexposed pixels on the relationship between optical diversity metrics and biodiversity indices were highlighted.
In the third part, we examined the relationship between PTs variability (at both local and community scales, measured by standard deviation and by the Euclidean distances of the biochemical and biophysical PTs respectively) and taxonomic diversity (both α-diversity and β-diversity, measured by Shannon’s index and by Jaccard dissimilarity index of the species, families, and functional groups percent cover respectively) in Monte Bondone, Trentino province, Italy. The results of the study showed that the PTs variability metrics at alpha scale were not correlated with α-diversity. However, the results at the community scale (β-diversity) showed that some of the investigated biochemical and biophysical PTs variations metrics were associated with β-diversity. The SVH approach was also tested to estimate β-diversity and we found that spectral diversity calculated by spectral angular mapper (SAM) showed to be a better proxy of biodiversity in the same ecosystem where the spectral diversity failed to estimate alpha diversity, this leading to the conclusion that the link between functional and species diversity may be an indicator of the applicability of optical sampling methods to estimate biodiversity.
The findings of the thesis highlighted that grassland structural heterogeneity strongly affects the ability to retrieve both LAI and biodiversity, with high uncertainties due to structural and biochemical PTs co-variation at complex grassland ecosystems. In this context, the uncertainties of satellite-based products (e.g., LAI) in monitoring grassland canopies characterized by either spatially or temporally varying structure need to be carefully taken into account. The results of the study highlighted that the poor performance of optical diversity proxies in estimating biodiversity in structurally heterogeneous grasslands might be due to the complex relationships between functional diversity and biodiversity, rather than the impossibility to detect functional diversity with spectral proxies.
2
Andersson, Bea Angelica. « Analysis of Selection and Genetic Drift in a Dioecious Plant : Spatial Genetic Structure and Selection in Phenotypic Traits in a Young Island Population of Silene dioica ». Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-96275.
Texte intégralRésumé :
Selection and genetic drift are often competing forces in shaping genetic structure in populations. Genetic drift will often effectively cancel out the effect of selection when population sizes are small, such as in colonizing island populations. On a small island in the Skeppsvik Archipelago in northern Sweden, a newly founded population of Silene dioica has been monitored since it first established around 1993. Though inhabiting an area of merely 173 m2, the population has been shown to exhibit a genetically differentiated patch structure where closely related individuals are tightly grouped, distanced from other family groups. In this study, the effect of selection was evaluated as compared to that of genetic drift. Variation in phenotypic traits in flowers, leaves and stalks were compared to that of neutral markers, in the form of PST and FST measures, to assess a measure of what proportion of differentiation among patches in phenotypic traits could not be attributed to genetic drift. Males and females were analysed separately to obtain measures of sex specific selection. Signs of divergent and stabilizing selection were found in several traits in both males and females despite the small spatial scale and short time since colonization. Further analysis is needed to assess explanations for trait divergence among patches and direction of selection.
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IMRAN, HAFIZ ALI. « Remote sensing tools for monitoring grassland plant leaf traits and biodiversity ». Doctoral thesis, 2022. http://hdl.handle.net/10449/74719.
Texte intégralRésumé :
Grasslands are one of the most important ecosystems on Earth, covering approximately onethird of the Earth’s surface. Grassland biodiversity is important as many services provided by such
ecosystems are crucial for the human economy and well-being. Given the importance of grasslands
ecosystems, in recent years research has been carried out on the potential to monitor them with
novel remote sensing techniques. Improved detectors technology and novel sensors providing finescale hyperspectral imagery have been enabling new methods to monitor plant traits (PTs) and
biodiversity.
The aims of the work were to study different approaches to monitor key grassland PTs such
as Leaf Area Index (LAI) and biodiversity-related traits. The thesis consists of 3 parts: 1)
Evaluating the performance of remote sensing methods to estimate LAI in grassland ecosystems, 2)
Estimating plant biodiversity by using the optical diversity approach in grassland ecosystems, and
3) Investigating the relationship between PTs variability with alpha and beta diversity for the
applicability of the optical diversity approach in a subalpine grassland of the Italian Alps
To evaluate the performance of remote sensing methods to estimate LAI, temporal and
spatial observations of hyperspectral reflectance and LAI were analyzed at a grassland site in Monte
Bondone, Italy (IT-MBo). In 2018, ground temporal observations of hyperspectral reflectance and
LAI were carried out at a grassland site in Neustift, Austria (AT-NEU). To estimate biodiversity, in
2018 and 2019 a floristics survey was conducted to determine species composition and
hyperspectral data were acquired at two grassland sites: IT-MBo and University of Padova’s
Experimental Farm, Legnaro, Padua, Italy (IT-PD) respectively. Furthermore, in 2018,
biochemistry analysis of the biomass samples collected from the grassland site IT-MBo was carried
out to determine the foliar biochemical PTs variability.
The results of the thesis demonstrated that the grassland spectral response across different
spectral regions (Visible: VIS, red-edge: RE, Near-infrared: NIR) showed to be both site-specific
and scale-dependent. In the first part of the thesis, the performance of spectral vegetation indices
(SVIs) based on visible, red-edge (RE), and NIR bands alongside SVIs solely based or NIRshoulder bands (wavelengths 750 - 900 nm) was evaluated. A strong correlation (R2 > 0.8) was
observed between grassland LAI and both RE and NIR-shoulder SVIs on a temporal basis, but not
on a spatial basis. Using the PROSAIL Radiative Transfer Model (RTM), it was demonstrated that
grassland structural heterogeneity strongly affects the ability to retrieve LAI, with high uncertainties
due to structural and biochemical PTs co-variation.
In the second part, the applicability of the spectral variability hypothesis (SVH) was
questioned and highlighted the challenges to use high-resolution hyperspectral images to estimate
biodiversity in complex grassland ecosystems. It was reported that the relationship between
biodiversity (Shannon, Richness, Simpson, and Evenness) and optical diversity metrics (Coefficient
of variation (CV) and Standard deviation (SD)) is not consistent across plant communities. The
results of the second part suggested that biodiversity in terms of species richness could be estimated
by optical diversity metrics with an R2 = 0.4 at the IT-PD site where the grassland plots were
artificially established and are showing a lower structure and complexity from the natural grassland
plant communities. On the other hand, in the natural ecosystems at IT-MBo, it was more difficult to
estimate biodiversity indices, probably due to structural and biochemical PTs co-variation. The
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effects of canopy non-vegetative elements (flowers and dead material), shadow pixels, and
overexposed pixels on the relationship between optical diversity metrics and biodiversity indices
were highlighted.
In the third part, we examined the relationship between PTs variability (at both local and
community scales, measured by standard deviation and by the Euclidean distances of the
biochemical and biophysical PTs respectively) and taxonomic diversity (both α-diversity and βdiversity, measured by Shannon’s index and by Jaccard dissimilarity index of the species, families,
and functional groups percent cover respectively) in Monte Bondone, Trentino province, Italy. The
results of the study showed that the PTs variability metrics at alpha scale were not correlated with
α-diversity. However, the results at the community scale (β-diversity) showed that some of the
investigated biochemical and biophysical PTs variations metrics were associated with β-diversity.
The SVH approach was also tested to estimate β-diversity and we found that spectral diversity
calculated by spectral angular mapper (SAM) showed to be a better proxy of biodiversity in the
same ecosystem where the spectral diversity failed to estimate alpha diversity, this leading to the
conclusion that the link between functional and species diversity may be an indicator of the
applicability of optical sampling methods to estimate biodiversity.
The findings of the thesis highlighted that grassland structural heterogeneity strongly affects
the ability to retrieve both LAI and biodiversity, with high uncertainties due to structural and
biochemical PTs co-variation at complex grassland ecosystems. In this context, the uncertainties of
satellite-based products (e.g., LAI) in monitoring grassland canopies characterized by either
spatially or temporally varying structure need to be carefully taken into account. The results of the
study highlighted that the poor performance of optical diversity proxies in estimating biodiversity in
structurally heterogeneous grasslands might be due to the complex relationships between functional
diversity and biodiversity, rather than the impossibility to detect functional diversity with spectral
proxies
Livres sur le sujet "Plant traits (PTs)"
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Liede-Schumann, Sigrid, Ulrich Meve, Gildas Gâteblé, Gabrielle Barriera et Silvio Fici. Apocynaceae pro parte, Phellinaceae, Capparaceae : Flore de la Nouvelle Calédonie, volume 27. Publications scientifiques du Muséum, Paris ; IRD, Marseille, 2020. http://dx.doi.org/10.5852/fft49.
Texte intégralRésumé :
L’exceptionnelle richesse floristique de la Nouvelle-Calédonie est mondialement connue. Plus de 3 400 espèces de plantes vasculaires indigènes y sont répertoriées, dont les trois-quarts sont endémiques de l’archipel. L’endémisme ne concerne pas seulement les espèces, mais aussi les genres (près d’une centaine) et même trois familles. La diversité se décline aussi sur le plan écologique, en lien avec l’histoire géologique originale de la Nouvelle-Calédonie, qui a favorisé le micro-endémisme et les espèces inféodées aux substrats ultramafiques. De nouvelles espèces continuent à être découvertes, aussi reste-t-il nécessaire de poursuivre prospections et recherches botaniques, afin de mieux comprendre l’origine et l’évolution de cette flore, et contribuer à sa préservation. Le présent volume regroupe trois familles d’Angiospermes. Celle des Apocynaceae dont la classification a été profondément remaniée depuis la publication en 1981 du fascicule « Apocynaceae », volume 10 de la Flore de la Nouvelle-Calédonie et Dépendances : les trois sous-familles traitées ici (Periplocoideae, Secamonoideae et Asclepiadoideae) formaient auparavant la famille des Asclepiadaceae. Les Phellinaceae qui, avec 10 espèces ligneuses, constituent l’une des trois familles endémiques du territoire. Enfin, la Nouvelle-Calédonie héberge quelques espèces de la famille cosmopolite des Capparaceae, toutes appartenant au genre du câprier (Capparis). Conformément à la ligne éditoriale de la collection, cet ouvrage comporte, pour chaque famille traitée indépendamment : une présentation générale suivie de descriptions détaillées des genres et des espèces ; des clés d’identification, en français et en anglais ; une illustration variée comprenant des dessins au trait et des photographies des plantes vivantes ; des cartes de répartition et une évaluation des besoins de conservation selon les critères de l’UICN.
Chapitres de livres sur le sujet "Plant traits (PTs)"
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Karunananda, Dayani, Ramya Ranathunga et Wathsala Abeysinghe. « 60Co gamma irradiation-induced mutation in vegetatively propagated Philodendron erubescens 'Gold'. » Dans Mutation breeding, genetic diversity and crop adaptation to climate change, 386–98. Wallingford : CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0040.
Texte intégralRésumé :
Abstract Philodendron erubescens 'Gold', an ornamental plant and a popular climber with brilliant greenish yellow leaves, is used in indoor gardening and landscaping. It is commonly propagated through vegetative cuttings, thus incorporation of new traits through conventional breeding is impracticable. As commercial floriculture always demands novel varieties, this study was carried out to induce mutation in P. erubescens 'Gold' leaves using gamma- ray irradiation. Rooted cuttings (n = 200) of P. erubescens 'Gold' were subjected to 70 Gy, 100 Gy and 150 Gy gamma-rays and recovered on a propagator. Surviving shoots were transferred to pots. Regenerated shoots were multiplied vegetatively and ten M1 lines were maintained as M1-1 to M1-10 for 12 generations (M1V12) to evaluate growth and morphological variations along with their genetic stability. Of all 70 Gy and 100 Gy treated cuttings, 24 and two, respectively, survived after 6 months. Most of the irradiated plants had lost regeneration ability except for two M1 plants, which also showed comparatively reduced growth (one leaf in 45 days). Only one regenerated M1 plant showed morphological variation in its leaves and it was multiplied and maintained as lines. Several variations, including characteristics of leaves (shape, size, colour), stems (internodal length and branching) and plant stature, were observed among M1 lines and in subsequent vegetative generations. Leaves had three different colour patches, but neither the colour nor its distribution pattern was uniform or stable. The M1-4 line showed the highest stability of colour distribution in leaves; the colour composition of its leaves ranged as 0-10% dark bluish green, 60-90% strong yellow green and 10-30% brilliant greenish yellow throughout the 12 generations. This study demonstrates that gamma irradiated P. erubescens 'Gold' line M1-4 can be a promising mutant to develop as a new Philodendron cultivar.
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Aloo, Becky Nancy, Ernest Rashid Mbega et Billy Amendi Makumba. « Sustainable Food Production Systems for Climate Change Mitigation : Indigenous Rhizobacteria for Potato Bio-fertilization in Tanzania ». Dans African Handbook of Climate Change Adaptation, 1–27. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-42091-8_276-1.
Texte intégralRésumé :
AbstractThe global rise in human population has led to the intensification of agricultural activities to meet the ever-rising food demand. The potato (Solanum tuberosum L.) is a crop with the potential to tackle food security issues in developing countries due to its short growth cycle and high nutrient value. However, its cultivation is heavily dependent on artificial fertilizers for yield maximization which culminates in global warming and other environmental problems. There is need, therefore, for its alternative fertilization technologies to mitigate climate change. This study evaluated the potential of indigenous rhizobacteria for potato cropping in Tanzania. Ten potato rhizobacterial isolates belonging to Enterobacter, Klebsiella, Citrobacter, Serratia, and Enterobacter genera were obtained from a previous collection from different agro-ecological areas in Tanzania. The isolates were characterized culturally, microscopically, biochemically, and by their carbohydrate utilization patterns. Their in vitro plant growth-promoting (PGP) traits such as nitrogen fixation, solubilization of phosphates, potassium, and zinc, and production of siderophores, indole acetic acid, and gibberellic acids were then evaluated. Lastly, sterilized potato seed tubers were bacterized with the inoculants and grown in pots of sterile soil in a screen-house using untreated plants as a control experiment. The potato rhizobacterial isolates had varying characteristics and showed varying in vitro PGP activities. The screen-house experiment also showed that the rhizobacterial treatments significantly (p < 0.05) enhanced different parameters associated with potato growth by up to 91% and established the potential of most of the isolates as alternative biofertilizers in potato cropping systems in Tanzania.
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Aloo, Becky Nancy, Ernest Rashid Mbega et Billy Amendi Makumba. « Sustainable Food Production Systems for Climate Change Mitigation : Indigenous Rhizobacteria for Potato Bio-fertilization in Tanzania ». Dans African Handbook of Climate Change Adaptation, 1469–95. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_276.
Texte intégralRésumé :
AbstractThe global rise in human population has led to the intensification of agricultural activities to meet the ever-rising food demand. The potato (Solanum tuberosum L.) is a crop with the potential to tackle food security issues in developing countries due to its short growth cycle and high nutrient value. However, its cultivation is heavily dependent on artificial fertilizers for yield maximization which culminates in global warming and other environmental problems. There is need, therefore, for its alternative fertilization technologies to mitigate climate change. This study evaluated the potential of indigenous rhizobacteria for potato cropping in Tanzania. Ten potato rhizobacterial isolates belonging to Enterobacter, Klebsiella, Citrobacter, Serratia, and Enterobacter genera were obtained from a previous collection from different agro-ecological areas in Tanzania. The isolates were characterized culturally, microscopically, biochemically, and by their carbohydrate utilization patterns. Their in vitro plant growth-promoting (PGP) traits such as nitrogen fixation, solubilization of phosphates, potassium, and zinc, and production of siderophores, indole acetic acid, and gibberellic acids were then evaluated. Lastly, sterilized potato seed tubers were bacterized with the inoculants and grown in pots of sterile soil in a screen-house using untreated plants as a control experiment. The potato rhizobacterial isolates had varying characteristics and showed varying in vitro PGP activities. The screen-house experiment also showed that the rhizobacterial treatments significantly (p < 0.05) enhanced different parameters associated with potato growth by up to 91% and established the potential of most of the isolates as alternative biofertilizers in potato cropping systems in Tanzania.
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Singh, Shipra, et Abhishek K. Verma. « Plant Functional Traits in Tropical Dry Forests ». Dans Practice, Progress, and Proficiency in Sustainability, 66–88. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0014-9.ch004.
Texte intégralRésumé :
Plants have certain characteristics which allow them to respond to various environmental conditions, like changes in climate, water scarcity in the soil, lack of minerals; among others. In some of these traits, the responses to climatic phenomena such as drought can be evidenced through morphological adaptations (spines, succulent tissues, trichomes) or physiological adaptations (regulation of water potential at the cellular level, the concentration of nutrients, etc.). A systematic literature review was performed to study plant functional traits (PFTs) in tropical dry forests (TDFs). The chapter suggests the role of functional traits in community dynamics and processes. The authors will also highlight the limitations of PFTs in TDFs and how they can be improved.
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Singh, Shipra, et Abhishek K. Verma. « Plant Functional Traits in Tropical Dry Forests ». Dans Research Anthology on Ecosystem Conservation and Preserving Biodiversity, 852–74. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5678-1.ch043.
Texte intégralRésumé :
Plants have certain characteristics which allow them to respond to various environmental conditions, like changes in climate, water scarcity in the soil, lack of minerals; among others. In some of these traits, the responses to climatic phenomena such as drought can be evidenced through morphological adaptations (spines, succulent tissues, trichomes) or physiological adaptations (regulation of water potential at the cellular level, the concentration of nutrients, etc.). A systematic literature review was performed to study plant functional traits (PFTs) in tropical dry forests (TDFs). The chapter suggests the role of functional traits in community dynamics and processes. The authors will also highlight the limitations of PFTs in TDFs and how they can be improved.
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Schertz, Keith, Yann-rong Lin, Andrew Paterson et Zhikang Li. « Case History in Plant Domestication ». Dans Molecular Dissection of Complex Traits, 187–95. CRC Press, 1997. http://dx.doi.org/10.1201/9781420049381.pt2.
Texte intégral
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Alina Mofokeng, Maletsema, Zaid Bello et Kingstone Mashingaidze. « Phenotypic Analysis of Pigeon Pea Reveal Genotypic Variability under Different Environmental Interaction ». Dans Legumes Research - Volume 1. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99285.
Texte intégralRésumé :
Pigeon pea is one of the most important leguminous crop globally. However it is a neglected pulse crops in South Africa in terms of research and production. Most farmers grow local landraces with low yields and there is lack of diverse material. The objective of the study was to determine the presence of genetic diversity among the pigeon pea genotypes using quantitative and qualitative phenotypic traits. The trials were conducted in Mafikeng and Nelspruit in South Africa. The trials were laid out in randomised complete block designs replicated three times. The quantitative and qualitative phenotypic data were recorded according to pigeon pea descriptor list. The phenotypic data were analysed using analysis of variance, Pearson’s correlations, principal component analysis, and biplots constructed using principal coordinate analysis, Shannon weaver diversity indices and frequencies. The results showed highly significant differences among the genotypes based on plant height, pod bearing and seed number per pod meaning there was vast genetic diversity among the genotypes. Seed yield was positively correlated with seed number per pod, seed number per plant and pod weight whereas pod bearing was negatively associated with hundred seed weight meaning improving seed yield will automatically improve other positively correlated traits. Principal component analysis showed five most important PCs contributing to a total variation of 84.7%. The traits that contributed to the most variation to the total variation observed were plant height, pod length, seed yield, pod bearing and days to flowering. The Shannon weaver indices ranged between 0.98 and 1.00 showing the presence of variation among the qualitative traits measured. The clustering grouped genotypes into three clusters with Tumia and ICEAP 00540 being the most diverse. The diverse genotypes can be used as parents for hybridization and development of transgressive segregants in breeding programmes. There was vast presence of genetic diversity among the pigeon pea genotypes evaluated.
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Sady-Bugajska, Agata. « Analiza taksonomiczna pozostałości drewna z cmentarzyska w Świbiu / Taxonomic analysis of wood remains from the cemetery at Świbie ». Dans Cmentarzysko w wczesnej epoki żelaza w Świbiu na Górnym Śląsku. Tom 2, 192–215. Wydawnictwo Profil-Archeo, 2022. http://dx.doi.org/10.33547/swibie2022.2.11.
Texte intégralRésumé :
In addition to typical artefacts, the archaeological research at Świbie also produced a significant amount of plant materials. Due to the nature of the site as a biritual cemetery, these were mainly fragments of wood preserved either in dried and mineralised form or in charred form, i.e. as charcoal. The analysis covered plant remains originating from 102 graves, with 65 samples coming from inhumation graves and 20 from cremation graves (of which 17 were from cremations in pits, including animal burials, and three from urned cremations). In addition, 17 samples came from biritual burials (of which 16 were combinations of an inhumation grave and a cremation in pit, whereas one – an inhumation with urned cremation). Moreover, 21 samples from non-sepulchral contexts were analysed, originating mostly from hearths located close to graves. Charcoal fragments were preserved in 100 graves. They were remains of cremation pyres and hearths. Fragments of unburnt wood, recovered from 15 graves (mostly inhumations), were remains of pads found under bronze objects. The species prevailing in the material was Scots pine (Pinus sylvestris), with oak (Quercus sp.) also frequent. Both were used for building cremation pyres. Birch (Betula sp.) came third in terms of frequency of remains. Apart from these, charred remains of fir (Abies alba), alder (Alnus sp.), and ash (Fraxinus excelsior) were identified in the graves. Spruce/larch (Picea abies/Larix sp.), beech (Fagus sylvatica) and elm (Ulmus sp.) occurred occasionally. In addition to Scots pine, spruce/larch, ash, birch, and oak, traces of burnt wood of probably maple (cf. Acer sp.) and poplar (cf. Populus sp.) were identified in the material coming from outside the graves (from the hearths). The taxonomic composition obtained on the basis of wood remains from the Świbie cemetery is similar to the results of anthracological and xylological studies of other necropolises. Fragments described as the remains of “wooden pads” are very interesting finds. These are small fragments of wood preserved in a highly mineralised or dried (?) form, often with a greenish-blue coating. Their analysis was very difficult, but positive results in the form of a taxonomic identification could nevertheless be obtained for 11 samples. Virtually all of the pads were made of oak wood. In the sample from grave 79, several fragments of birch (Betula sp.) bark were preserved alongside fragments of pads. In a few cases, wooden pads preserved traces of other organic materials. These were mostly fragments of fabric, but remains possibly interpretable as straw remains were also recorded. The “pads” themselves were most likely modest remnants of wooden biers, preserved thanks to the preservation properties of metal corrosion compounds. Wood remains, mostly charcoal, are among the most common plant materials found at archaeological sites. Their analysis reveals which species of trees and shrubs were used by people, and it also provides information on surrounding forest communities.
Actes de conférences sur le sujet "Plant traits (PTs)"
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Esmail, Essam L., et Anahed H. Juber. « An Application of Graph Theory for the Detection of Degenerate Structures in Planetary Gear Trains ». Dans ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-67479.
Texte intégralRésumé :
Abstract One of the most important steps in the structural synthesis of planetary gear trains is to eliminate degenerate structures. First, the graph theory is used to represent planetary gear trains (PGTs). Second, a procedure is developed to identify fundamental geared entities (FGEs). Further, the single-planet FGEs are shown to have one-DOF and, therefore, cannot constitute a degenerate structure. It is this that allows a significant reduction in the calculation in relation to other methods of diagnosing degenerate structures. Third, using the concepts of FGEs and the notation of the associated adjacency matrix, an algorithm is developed for the detection of degenerate structures in PGTs. The algorithm is based on the fact that any degenerate structure is a PGT formed by two fundamental geared entities with common edges and/or vertices equal to or more than 3. Forth, the concept of connectivity between single-planet FGEs is introduced and a simple, straightforward approach for deducting the connectivity matrix from the adjacency matrix is developed. The new vertex-edge mobility criterion does not require combinatorial analysis. Besides, the method is applicable to one and multiple degrees of freedom PGTs, it is also applicable to multi-planet PGTs and complex PGTs, including contrary examples found in the literature.
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Yunda Lozano, Juan Guillermo. « APLICACIÓN DE SISTEMAS INFORMÁTICOS PARA COMPARAR ESCENARIOS DE CRECIMIENTO URBANO ». Dans Seminario Internacional de Investigación en Urbanismo. Bogotá : Universidad Piloto de Colombia, 2022. http://dx.doi.org/10.5821/siiu.9991.
Texte intégralRésumé :
ABSTRACT
Since 1997 the so-called Planes Parciales (PP) were introduced in Colombia. These are planning tools for real estate development designed to distribute equally the burdens and benefits between developers and the public sector. PPs, however, are criticized arguing that they develop high densities without considering impacts on the environment and on the urban infrastructure. On the other hand, Planning Support Systems (PSS) are new tools that allow to quickly obtain indicators of impacts and sustainability of urban projects. To understand and validate the criticisms of PP, this work applied the PSS tool, Envision Tomorrow, comparing growth through a PP with the traditional Low Density and Informal urban growth models. PPs were found to be more convenient for the city and for sustainability than Low Density. However, when faced with the Informal model, they have challenges of housing costs and mix of uses.
Keywords: plan parcial, planning support systems, urban growth scenarios, Bogota
Topic: 2. Urban Morphologies RESUMEN
Desde 1997 en Colombia fueron introducidos los Planes Parciales (PP), que son herramientas para el desarrollo inmobiliario, diseñadas para repartir equitativamente las cargas y beneficios entre los promotores y el sector público. Los PP son criticados argumentando que desarrollan altas densidades sin contemplar impactos en el entorno ambiental y en la precaria infraestructura. Por otro lado, los Sistemas de Soporte a la Planeación (SSP) son nuevas herramientas que permiten obtener rápidamente indicadores de impactos y sostenibilidad de proyectos urbanos. Para entender y validar las críticas a los PP, este trabajo aplicó la herramienta SSP, Envision Tomorrow comparando el crecimiento a través de Plan Parcial con los modelos tradicionales de Baja Densidad e Informal. Se encontró que los PP son más convenientes para la ciudad y para la sostenibilidad que la Baja Densidad. Sin embargo, frente al Informal tienen retos de costos de vivienda y mezcla de usos.
Palabras clave: plan parcial, sistemas de soporte a la planeación, escenarios de crecimiento urbano, Bogotá
Bloque temático: 2. Morfologías urbanas
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Fukuda, Tomoki, Masao Nakagawa, Syota Matsui, Toshiki Hirogaki et Eiichi Aoyama. « Investigation of Planet Gear Motion in a Planetary Gear Train With Direct High Speed Monitoring ». Dans ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85505.
Texte intégralRésumé :
Planetary gear trains (PGTs) are widely applied in various machines owing to their advantages, such as compactness, low weight, and high torque capacity. However, they experience the problems of vibration due to the structural and motional complexities caused by planet gears. In a previous study, it was shown that high speed monitoring is effective for evaluating the motion of planet gears under steady conditions and transient conditions including the influence of backrush. However graphical investigation was conducted manually, and improvement in accuracy is required. In this report, an improved method is proposed, which includes lighting conditions and measurement conditions. Throughout these improvement processes, instant center of rotation is calculated automatically with detected coordinates using software. This makes it possible to estimate the transient response of PGTs with planet gear motion.
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Hamada, Seiya, Masao Nakagawa, Tomoki Fukuda, Toshiki Hirogaki et Eiichi Aoyama. « Investigation on Influence of Tooth Precision on Meshing Noise of Planetary Gear Train ». Dans ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-97682.
Texte intégralRésumé :
Abstract Noise is one of the major serious issues for planetary gear trains (PGTs). This noise is regarded as a noise hazard in certain cases such as helicopter cabins where the sound level reaches 100dB. Herein, planet gears of several precisions are combined to investigate the influence of tooth precision on meshing noise of PGT. The meshing noise of PGTs is generated by stiffness coefficient excitation and error excitation forces; however, the stiffness coefficient excitation is assumed to be constant in this paper because a slight error on the tooth surface does not affect the meshing stiffness. It was found that maintaining the same precision for all planet gears is the best. If one of the planet gears has a precision that is significantly different from that of the others, the sound pressure level increases. The deviation for the maximum error among all meshing pairs, should be restricted to no more than 3μm in case of module one spur gear.
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Yang, Jianming, et Ping Yang. « Dynamics Analysis of Planetary Gear Trains in a Wind Turbine Under Mean Wind Speed ». Dans ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71338.
Texte intégralRésumé :
Targeting at planetary gear trains (PGTs) used in wind turbines, this paper investigates their vibration and dynamics under the aerodynamic torque of mean wind speed. Wind shear and tower shadow effects are considered in modeling the torque. A lumped parameter model is then developed to calculate the vibration and dynamics response of the PGT to the aerodynamic torque. In this model, the gear teeth and bearings are modeled as springs and the rotation of the carrier and the planet gears as well as the translation of the sun gear are taken into account. The time varying effect of the stiffness of gear mesh is incorporated into the model. Newmark algorithm is used to solve the vibration model established. In the last, the vibration response and dynamic meshing forces of the PGT are simulated and analyzed for rotors with 2 blades and 3 blades. The simulation result demonstrates that the aerodynamic torque is not a constant even under a constant wind speed. Instead, it changes with a frequency which equals the fundamental rotor frequency multiplied by the number of blades. The torque fluctuation causes corresponding vibration response and dynamic force fluctuation in the PGT.
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Llerena Sandoya, Lisse, et Gabriela Vega. « Partial plan for the environmental conservation and historical and tourist development of the Peñón del Río hill, Durán, 2022 ». Dans 8th International Conference on Human Interaction and Emerging Technologies. AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1002715.
Texte intégralRésumé :
In the north of the Durán canton, is located the hill called "Peñón del Rio", a natural elevation suitable for the development of agricultural and livestock activities, surrounded by rivers and streams that also harbor a dense amount of vegetative species. Archeological remains such as ceramics and burial pits from different cultures of the area were also found. The dry forest is one of the most threatened ecosystems and it is estimated that between 60% and 75% of it has disappeared. On the other hand, the sector is being seriously affected by the extraction of stone material, causing great damage to its ecosystem, to this is added the psychological and health damages caused by the noise, the trembling caused by the implosions executed, and the cloud of dust raised by the passage of heavy machinery; and finally, the high crime rate by which it is affected due to its abandonment. The purpose of this study is to develop a partial plan proposal, in which environmental and arqueological conservation areas of this natural elevation are determined to promote the preservation of the native flora avoiding the loss of identity of the vegetation, as well as the historical importance of the area, potentiating its tourist value, for which, through the observation technique and the handling of field cards, the identification of the plant species of the sector and the diagnosis of the affectation by the excavation of the stone material were carried out. In addition, georeferenced information on the trails and rest areas was collected with the help of Geographic Information Systems. To complement the study, qualitative research instruments were used to determine strategies for the conservation of green areas and the archaeological importance of the hill. As a result, a proposal was made for the location of walking trails, viewpoints and other rest areas, establishing their conservation and reforestation areas. In conclusion, the observed findings show historical roots of the Durán canton and even pre-Hispanic roots at the Latin American level, and the design of trails and rest areas, potentiate the tourist value of this natural elevation.
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Micó Romero, Noelia. « Problèmes de terminologie dans « Shipboard Oil Pollution Emergency Plan/ Plan d’urgence de bord contre la pollution par les hydrocarbures » sur la Méditerranée à partir d’une traduction de l’anglais vers le français. » Dans XXV Coloquio AFUE. Palabras e imaginarios del agua. Valencia : Universitat Politècnica València, 2016. http://dx.doi.org/10.4995/xxvcoloquioafue.2016.3058.
Texte intégralRésumé :
Dans notre communication nous essayons de décrire comment les langues (en l’occurrence l’anglais, le français et de forme subsidiaire l’espagnol) appréhendent une petite parcelle de la réalité : la pollution des hydrocarbures. Notre cadre conceptuel s’aligne avec la sémantique cognitive, centrée sur la perception expérientielle du sujet parlant, tout en dépassant ainsi le modèle des conditions nécessaires et suffisantes (CNS) initié par Aristote et celui de la sémantique compositionnelle du structuralisme. Par contre, la sémantique cognitive (Rosch, Putnam, Kleiber) se base sur la « Embodied Cognition Thesis », la « Thèse de la cognition incarnée », selon laquelle notre corps influe sur notre langage, notre pensée, nos concepts. Cette approche introduit la théorie du prototype où Kleiber (1990) traite la catégorisation à partir du « meilleur exemplaire » et de la notion de « ressemblance de famille ». Dans notre étude, nous analysons comment l’anglais, le français et l’espagnol catégorisent la même réalité à partir du texte « Plan d’urgence de bord contre la pollution par les hydrocarbures », traduit de l’anglais. Dans un premier temps, nous aborderons des questions générales sur les caractéristiques des textes techniques tant en anglais comme en français et dans un deuxième temps, nous commenterons les différentes traductions en les groupant par domaines ou champs sémantiques (i.e. parties du bateau, équipage,…) En somme, des termes techniques qui ne seront pas analogues et dont les différences s’expliquent non seulement par la diversité des langues (aspects morphosyntaxiques, attribution, détermination etc.) mais aussi par des questions d’ordre différent que nous essayons de justifier à travers d’exemples tirés de notre corpus.DOI: http://dx.doi.org/10.4995/XXVColloqueAFUE.2016.3058
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Nowotny, S., H. Hillig, F. Kubisch, F. Toma et C. Leyens. « Advanced Processes and System Technology for High-Performance Laser Cladding ». Dans ITSC2017, sous la direction de A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen et C. A. Widener. DVS Media GmbH, 2017. http://dx.doi.org/10.31399/asm.cp.itsc2017p0400.
Texte intégralRésumé :
Abstract Laser cladding technology is widely used in industry to precisely apply tailored surface coatings, as well as three-dimensional deposits for repair and additive layer-by-layer fabrication of metallic parts. However, the processing of larger components, like tools for oil and gas production, is economically challenging due to the conventionally low deposition rates. Consequently, industry is requesting more powerful technologies that maintain the quality advantages of the laser technology, but also make the process more productive and time effective. The modern highest power diode lasers offer practical solutions for applying of large-area laser cladding with significantly increased productivity. Using a fiber-coupled diode laser of 20 kW power and the accordingly developed laser cladding heads, real deposition rates of metal alloys, e.g. Inconel 625, could reach 14 kg/h. With the new-developed powder nozzles with rectangular profile of the powder jet allows at a laser power of 20 kW single tracks with 45 mm-width can be produced. Besides the laser source, the processing laser head is the key parameter for a high productivity and efficiency of the whole cladding procedure. The paper presents a new generation of high-performance laser cladding heads with integrated process sensors, which guarantee a stable long-time operation at highest power levels. The deposition rates achieved with this technology are equal or even exceed typical values of the common PTA technique. Current applications are large-area coatings on power plant components, hydraulic cylinders for off-shore equipment, and large metal forming tools for automotive bodies.
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Mas, Vicente, et Giancarlo Cataldi. « Valencia : the territorial structures of the Roman city substratum. » Dans 24th ISUF 2017 - City and Territory in the Globalization Age. Valencia : Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/isuf2017.2017.5304.
Texte intégralRésumé :
Authors: Giancarlo Cataldi. Via dei Rustici 8, 50122 Firenze +39 055295380 Vicente Mas Llorens. Plaza de José María Orense 5 pta. 2. +34 629629226. Keywords: Roman Valencia, substratum permanent structures, city planning, historical transformations Text abstract: The shape of the territory and the urban settlement of numerous Valencian cities were strongly conditioned by the original imprinting of Roman planning, characterized –as it is known- by large scale infrastructures, by settlements of orthogonal axes and by the allocation of the plot division into square modular divisions called centuriae. All the later interventions took necessarily into account such structures, which underwent numerous transformations over time, especially from the second half of the twentieth century. Then innovations and developments in modern technology contributed –more than in any other period– to neglect and override the traces of the original configuration. Territorial and urban research into Roman structures in the Italian peninsula has allowed the recognition of a sufficiently large number of plans, thus allowing the development of a complete general research method to read analogous structures in different Romanized territories. The authors now propose to apply this method to the territory of the Valencian Community. The rectilinear outline of Via Augusta with its forking side paths, the orthogonal signs of the agrarian fabric, the military milestones and the administrative divisions suggest, also in this case, the possibility of retracing the original pattern. Its structure could contribute, among other things, to explain the logic of the expansions outside the walls of the historic centre of Valencia that might otherwise seem arbitrary and meaningless.
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Wahshi, Khalifa Omair, Boris Jean Thomas, Saud Ali Khaldi, Younis Said Haji, Yasir Mohammed Salehi, Roger Shihche Yuan, Ali Khalfan Mahrooqi, Khalid Nasser Harthy et Fahad Said Habsi. « Innovative Solutions to Subsurface Challenges in Deep Hard Rock High Temperature Slim Wells ». Dans ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211735-ms.
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Abstract In this paper we present the challenges faced in one of PDO's onshore a deep (5200 mTVD) field. Among these challenges were hardness of the rocks, 40 ksi and a high temperature of 155ºC. Further, well bore instability, tectonic stresses and depletion. The time consumed to overcome these subsurface challenges with conventional drilling methods was affecting the economic attractiveness of some of the wells. A multi-disciplinary taskforce was established with the remit to improve overall well economics by overcoming field challenges and by turning some of the challenges into opportunities. The working group identified opportunities across several themes that were deemed to have the highest impact on the well economics, well design and materials selections and new technologies. The introduction of a new design concept of (Fast Degradation Brine) in the annulus allowed a reduction of the brine weight after cementing the completion. This change enabled passing specific casing design burst loads associated with the reduction of the 7" liner weight from 35 to 29 ppf. This allowed drilling larger hole sizes of 6" and 6 1/8" instead of 5 7/8". H2S fugacity concept was used instead of the conventional partial pressure concept to evaluate the sour severity of the materials. In new technologies, Motorised Reamer Shoe (MSR) drive system, was piloted for the first time in PDO's cemented completion to enable re-drilling and reaming ledges and hole closure caused by tectonic stresses during the completion run. A Polymer Borate System (PBS) plug has proven to be an effective new technology, used as lost circulation material for dealing with severe losses in PDO. Through introduction of new well design concepts, new technologies and new ways of working we managed to: - Safeguard reserves and enable full access to target reservoirs by overcoming drilling challenges through improvements in the well design. - Realise a 40%-well delivery time reduction, coupled with a significant reduction in NPT. - 30%-reduction in average well cost. - Realise cost saving of 2.9% through well design optimisations. We managed to safeguard production which would be lost in case of short landing the completion. - Replicate MSR technology on planned side-tracks in PDO's wells, and we are planning to apply this technology in horizontal wells. The technology will also be an enabler to further slim down well designs in other fields. - Put in place a replication plan for applying the H2S fugacity concept wherever applicable. The well design concepts and new technologies mentioned above are novel or new to PDO.
Rapports d'organisations sur le sujet "Plant traits (PTs)"
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Cahaner, Avigdor, Susan J. Lamont, E. Dan Heller et Jossi Hillel. Molecular Genetic Dissection of Complex Immunocompetence Traits in Broilers. United States Department of Agriculture, août 2003. http://dx.doi.org/10.32747/2003.7586461.bard.
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Objectives: (1) Evaluate Immunocompetence-OTL-containing Chromosomal Regions (ICRs), marked by microsatellites or candidate genes, for magnitude of direct effect and for contribution to relationships among multiple immunocompetence, disease-resistance, and growth traits, in order to estimate epistatic and pleiotropic effects and to predict the potential breeding applications of such markers. (2) Evaluate the interaction of the ICRs with genetic backgrounds from multiple sources and of multiple levels of genetic variation, in order to predict the general applicability of molecular genetic markers across widely varied populations. Background: Diseases cause substantial economic losses to animal producers. Emerging pathogens, vaccine failures and intense management systems increase the impact of diseases on animal production. Moreover, zoonotic pathogens are a threat to human food safety when microbiological contamination of animal products occurs. Consumers are increasingly concerned about drug residues and antibiotic- resistant pathogens derived from animal products. The project used contemporary scientific technologies to investigate the genetics of chicken resistance to infectious disease. Genetic enhancement of the innate resistance of chicken populations provides a sustainable and ecologically sound approach to reduce microbial loads in agricultural populations. In turn, animals will be produced more efficiently with less need for drug treatment and will pose less of a potential food-safety hazard. Major achievements, conclusions and implications:. The PI and co-PIs had developed a refined research plan, aiming at the original but more focused objectives, that could be well-accomplished with the reduced awarded support. The successful conduct of that research over the past four years has yielded substantial new information about the genes and genetic markers that are associated with response to two important poultry pathogens, Salmonella enteritidis (SE) and Escherichia coli (EC), about variation of immunocompetence genes in poultry, about relationships of traits of immune response and production, and about interaction of genes with environment and with other genes and genetic background. The current BARD work has generated a base of knowledge and expertise regarding the genetic variation underlying the traits of immunocompetence and disease resistance. In addition, unique genetic resource populations of chickens have been established in the course of the current project, and they are essential for continued projects. The US laboratory has made considerable progress in studies of the genetics of resistance to SE. Microsatellite-marked chromosomal regions and several specific genes were linked to SE vaccine response or bacterial burden and the important phenomenon of gene interaction was identified in this system. In total, these studies demonstrate the role of genetics in SE response, the utility of the existing resource population, and the expertise of the research group in conducting such experiments. The Israeli laboratories had showed that the lines developed by selection for high or low level of antibody (Ab) response to EC differ similarly in Ab response to several other viral and bacterial pathogens, indicating the existence of a genetic control of general capacity of Ab response in young broilers. It was also found that the 10w-Ab line has developed, possibly via compensatory "natural" selection, higher cellular immune response. At the DNA levels, markers supposedly linked to immune response were identified, as well as SNP in the MHC, a candidate gene responsible for genetic differences in immunocompetence of chickens.
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Fahima, Tzion, et Jorge Dubcovsky. Map-based cloning of the novel stripe rust resistance gene YrG303 and its use to engineer 1B chromosome with multiple beneficial traits. United States Department of Agriculture, janvier 2013. http://dx.doi.org/10.32747/2013.7598147.bard.
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Research problem: Bread wheat (Triticumaestivum) provides approximately 20% of the calories and proteins consumed by humankind. As the world population continues to increase, it is necessary to improve wheat yields, increase grain quality, and minimize the losses produced by biotic and abiotic stresses. Stripe rust, caused by Pucciniastriiformisf. sp. tritici(Pst), is one of the most destructive diseases of wheat. The new pathogen races are more virulent and aggressive than previous ones and have produced large economic losses. A rich source for stripe-rust resistance genes (Yr) was found in wild emmer wheat populations from Israel. Original Project goals: Our long term goal is to identify, map, clone, characterize and deploy in breeding, novel wild emmer Yr genes, and combine them with multiple beneficial traits. The current study was aiming to map and clone YrG303 and Yr15, located on chromosome 1BS and combine them with drought resistance and grain quality genes. Positional cloning of YrG303/Yr15: Fine mapping of these genes revealed that YrG303 is actually allelic to Yr15. Fine genetic mapping using large segregating populations resulted in reduction of the genetic interval spanning Yr15 to less than 0.1 cM. Physical mapping of the YrG303/Yr15 locus was based on the complete chromosome 1BS physical map of wheat constructed by our group. Screening of 1BS BAC library with Yr15 markers revealed a long BAC scaffold covering the target region. The screening of T. dicoccoidesaccession-specific BAC library with Yr15 markers resulted in direct landing on the target site. Sequencing of T. dicoccoidesBAC clones that cover the YrG303/Yr15 locus revealed a single candidate gene (CG) with conserved domains that may indicate a role in disease resistance response. Validation of the CG was carried out using EMS mutagenesis (loss-of- function approach). Sequencing of the CG in susceptible yr15/yrG303 plants revealed three independent mutants that harbour non-functional yr15/yrG303 alleles within the CG conserved domains, and therefore validated its function as a Pstresistance gene. Evaluation of marker-assisted-selection (MAS) for Yr15. Introgressions of Yr15 into cultivated wheat are widely used now. Recently, we have shown that DNA markers linked to Yr15 can be used as efficient tools for introgression of Yr15 into cultivated wheat via MAS. The developed markers were consistent and polymorphic in all 34 tested introgressions and are the most recommended markers for the introgression of Yr15. These markers will facilitate simultaneous selection for multiple Yr genes and help to avoid escapees during the selection process. Engineering of improved chromosome 1BS that harbors multiple beneficial traits. We have implemented the knowledge and genetic resources accumulated in this project for the engineering of 1B "super-chromosome" that harbors multiple beneficial traits. We completed the generation of a chromosome including the rye 1RS distal segment associated with improved drought tolerance with the Yr gene, Yr15, and the strong gluten allele 7Bx-over-expressor (7Bxᴼᴱ). We have completed the introgression of this improved chromosome into our recently released variety Patwin-515HP and our rain fed variety Kern, as well as to our top breeding lines UC1767 and UC1745. Elucidating the mechanism of resistance exhibited by Yr36 (WKS1). The WHEAT KINASE START1 (WKS1) resistance gene (Yr36) confers partial resistance to Pst. We have shown that wheat plants transformed with WKS1 transcript are resistant to Pst. WKS1 is targeted to the chloroplast where it phosphorylates the thylakoid-associatedascorbateperoxidase (tAPX) and reduces its ability to detoxify peroxides. Based on these results, we propose that the phosphorylation of tAPX by WKS1 reduces the ability of the cells to detoxify ROS and contributes to cell death. Distribution and diversity of WKS in wild emmer populations. We have shown that WKS1 is present only in the southern distribution range of wild emmer in the Fertile Crescent. Sequence analysis revealed a high level of WKS1 conservation among wild emmer populations, in contrast to the high level of diversity observed in NB-LRR genes. This phenomenon shed some light on the evolution of genes that confer partial resistance to Pst. Three new WKS1 haplotypes displayed a resistance response, suggesting that they can be useful to improve wheat resistance to Pst. In summary, we have improved our understanding of cereals’ resistance mechanisms to rusts and we have used that knowledge to develop improved wheat varieties.
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Sela, Hanan, Eduard Akhunov et Brian J. Steffenson. Population genomics, linkage disequilibrium and association mapping of stripe rust resistance genes in wild emmer wheat, Triticum turgidum ssp. dicoccoides. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7598170.bard.
Texte intégralRésumé :
The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.
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Epel, Bernard, et Roger Beachy. Mechanisms of intra- and intercellular targeting and movement of tobacco mosaic virus. United States Department of Agriculture, novembre 2005. http://dx.doi.org/10.32747/2005.7695874.bard.
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To cause disease, plant viruses must replicate and spread locally and systemically within the host. Cell-to-cell virus spread is mediated by virus-encoded movement proteins (MPs), which modify the structure and function of plasmodesmata (Pd), trans-wall co-axial membranous tunnels that interconnect the cytoplasm of neighboring cells. Tobacco mosaic virus (TMV) employ a single MP for cell- cell spread and for which CP is not required. The PIs, Beachy (USA) and Epel (Israel) and co-workers, developed new tools and approaches for study of the mechanism of spread of TMV that lead to a partial identification and molecular characterization of the cellular machinery involved in the trafficking process. Original research objectives: Based on our data and those of others, we proposed a working model of plant viral spread. Our model stated that MPᵀᴹⱽ, an integral ER membrane protein with its C-terminus exposed to the cytoplasm (Reichel and Beachy, 1998), alters the Pd SEL, causes the Pd cytoplasmic annulus to dilate (Wolf et al., 1989), allowing ER to glide through Pd and that this gliding is cytoskeleton mediated. The model claimed that in absence of MP, the ER in Pd (the desmotubule) is stationary, i.e. does not move through the Pd. Based on this model we designed a series of experiments to test the following questions: -Does MP potentiate ER movement through the Pd? - In the presence of MP, is there communication between adjacent cells via ER lumen? -Does MP potentiate the movement of cytoskeletal elements cell to cell? -Is MP required for cell-to-cell movement of ER membranes between cells in sink tissue? -Is the binding in situ of MP to RNA specific to vRNA sequences or is it nonspecific as measured in vitro? And if specific: -What sequences of RNA are involved in binding to MP? And finally, what host proteins are associated with MP during intracellular targeting to various subcellular targets and what if any post-translational modifications occur to MP, other than phosphorylation (Kawakami et al., 1999)? Major conclusions, solutions and achievements. A new quantitative tool was developed to measure the "coefficient of conductivity" of Pd to cytoplasmic soluble proteins. Employing this tool, we measured changes in Pd conductivity in epidermal cells of sink and source leaves of wild-type and transgenic Nicotiana benthamiana (N. benthamiana) plants expressing MPᵀᴹⱽ incubated both in dark and light and at 16 and 25 ᵒC (Liarzi and Epel, 2005 (appendix 1). To test our model we measured the effect of the presence of MP on cell-to-cell spread of a cytoplasmic fluorescent probe, of two ER intrinsic membrane protein-probes and two ER lumen protein-probes fused to GFP. The effect of a mutant virus that is incapable of cell-to-cell spread on the spread of these probes was also determined. Our data shows that MP reduces SEL for cytoplasmic molecules, dilates the desmotubule allowing cell-cell diffusion of proteins via the desmotubule lumen and reduces the rate of spread of the ER membrane probes. Replicase was shown to enhance cell-cell spread. The data are not in support of the proposed model and have led us to propose a new model for virus cell-cell spread: this model proposes that MP, an integral ER membrane protein, forms a MP:vRNAER complex and that this ER-membrane complex diffuses in the lipid milieu of the ER into the desmotubule (the ER within the Pd), and spreads cell to cell by simple diffusion in the ER/desmotubule membrane; the driving force for spread is the chemical potential gradient between an infected cell and contingent non-infected neighbors. Our data also suggests that the virus replicase has a function in altering the Pd conductivity. Transgenic plant lines that express the MP gene of the Cg tobamovirus fused to YFP under the control the ecdysone receptor and methoxyfenocide ligand were generated by the Beachy group and the expression pattern and the timing and targeting patterns were determined. A vector expressing this MPs was also developed for use by the Epel lab . The transgenic lines are being used to identify and isolate host genes that are required for cell-to-cell movement of TMV/tobamoviruses. This line is now being grown and to be employed in proteomic studies which will commence November 2005. T-DNA insertion mutagenesis is being developed to identify and isolate host genes required for cell-to-cell movement of TMV.
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Mawassi, Munir, Adib Rowhani, Deborah A. Golino, Avichai Perl et Edna Tanne. Rugose Wood Disease of Grapevine, Etiology and Virus Resistance in Transgenic Vines. United States Department of Agriculture, novembre 2003. http://dx.doi.org/10.32747/2003.7586477.bard.
Texte intégralRésumé :
Rugose wood is a complex disease of grapevines, which occurs in all growing areas. The disease is spread in the field by vector transmission (mealybugs). At least five elongated-phloem- limited viruses are implicated in the various rugose wood disorders. The most fully characterized of these are Grapevine virus A (GV A) and GVB, members of a newly established genus, the vitivirus. GVC, a putative vitivirus, is much less well characterized than GV A or GVB. The information regarding the role of GVC in the etiology and epidemiology of rugose wood is fragmentary and no sequence data for GVC are available. The proposed research is aimed to study the etiology and epidemiology of rugose wood disease, and to construct genetically engineered virus-resistant grapevines. The objectives of our proposed research were to construct transgenic plants with coat protein gene sequences designed to induce post-transcriptional gene silencing (pTGS); to study the epidemiology and etiology of rugose wood disease by cloning and sequencing of GVC; and surveying of rugose wood- associated viruses in Californian and Israeli vineyards. In an attempt to experimentally define the role of the various genes of GV A, we utilized the infectious clone, inserted mutations in every ORF, and studied the effect on viral replication, gene expression, symptoms and viral movement. We explored the production of viral RNAs in a GV A-infected Nicotiana benthamiana herbaceous host, and characterized one nested set of three 5'-terminal sgRNAs of 5.1, 5.5 and 6.0 kb, and another, of three 3'-terminal sgRNAs of 2.2, 1.8 and 1.0 kb that could serve for expression of ORFs 2-3, respectively. Several GV A constructs have been assembled into pCAMBIA 230 I, a binary vector which is used for Angrobacterium mediated transformation: GV A CP gene; two copies of the GV A CP gene arranged in the same antisense orientation; two copies of the GV A CP gene in which the downstream copy is in an antigens orientation; GV A replicase gene; GV A replicase gene plus the 3' UTR sequence; and the full genome of GV A. Experiments for transformation of N. benthamiana and grapevine cell suspension with these constructs have been initiated. Transgenic N. benthamiana plants that contained the CP gene, the replicase gene and the entire genome of GV A were obtained. For grapevine transformation, we have developed efficient protocols for transformation and successfully grapevine plantlets that contained the CP gene and the replicase genes of GV A were obtained. These plants are still under examination for expression of the trans genes. The construction of transgenic plants with GV A sequences will provide, in the long run, a means to control one of the most prevalent viruses associated with grapevines. Our many attempts to produce a cDNA library from the genome of GVC failed. For surveying of rugose wood associated viruses in California vineyards, samples were collected from different grape growing areas and tested by RT-PCR for GV A, GVB and GVD. The results indicated that some of the samples were infected with multiple viruses, but overall, we found higher incidence of GVB and GV A infection in California vineyards and new introduction varieties, respectively. In this research we also conducted studies to increase our understanding of virus - induced rootstock decline and its importance in vineyard productivity. Our results provided supporting evidence that the rootstock response to virus infection depends on the rootstock genotype and the virus type. In general, rootstocks are differ widely in virus susceptibility. Our data indicated that a virus type or its combination with other viruses was responsible in virus-induced rootstock decline. As the results showed, the growth of the rootstocks were severely affected when the combination of more than one virus was present.