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1
Kawakami, Erika, Mioko Ataka, Tomonori Kume, Kohei Shimono, Masayoshi Harada, Takuo Hishi e Ayumi Katayama. "Root exudation in a sloping Moso bamboo forest in relation to fine root biomass and traits". PLOS ONE 17, n. 3 (24 marzo 2022): e0266131. http://dx.doi.org/10.1371/journal.pone.0266131.
Abstract (sommario):
Exudation by fine roots generally varies with their morphological traits, but the effect of belowground resource availability on the root exudation via root morphological traits and biomass remains unknown. We aimed to determine the effects of morphological and physiological traits on root exudation rates and to estimate stand-scale exudation (Estand) by measuring the mass, length, and surface area of fine roots in a Moso bamboo forest. We measured root exudation as well as morphological and physiological traits in upper and lower plots on a slope with different belowground resource availability. The mean (± S.D.) root exudation rates per mass in the upper and lower slope were 0.049 ± 0.047 and 0.040 ± 0.059 mg C g-1 h-1, respectively, which were in the range of exudation found in woody forest ecosystems. We observed significant relationships between root exudation per mass and root respiration, as well as specific root length and surface area. In contrast, exudation per length and area did not correlate with morphological traits. The morphological traits did not differ between slope positions, resulting in no significant difference in root exudation per mass. Fine root biomass, length, and surface area on a unit ground basis were much higher in the lower than those in the upper slope positions. Estand was higher when estimated by mass than by length and area because the morphological effect on exudation was ignored when scaled using mass. Estand was 1.4–2.0-fold higher in the lower than that in upper slope positions, suggesting that the scaling parameters of mass, length, and area determined the Estand estimate more than the exudation rate per mass, length, and area. Regardless of scaling, Estand was much higher in the Moso bamboo forest than in other forest ecosystems because of a large fine-root biomass.
2
Yang, Liu, Xiuwei Wang, Zijun Mao, Zhiyan Jiang, Yang Gao, Xiangwei Chen e Doug P. Aubrey. "Root Exudation Rates Decrease with Increasing Latitude in Some Tree Species". Forests 11, n. 10 (28 settembre 2020): 1045. http://dx.doi.org/10.3390/f11101045.
Abstract (sommario):
Research Highlights: Understanding of the spatial variation of root exudation on a regional scale can help understand the response of plant physiological activities to environmental changes. Background and Objectives: Although root exudation has become an important topic in belowground ecology, its relationship with root traits and environmental factors is poorly understood. Our objective was to explore how root traits and environmental factors influence root exudation. Materials and Methods: We used a multi-factorial design consisting of three tree species spanning across sites located at three latitudes to assess root exudation dynamics, which was measured using a syringe-basis incubation system. Results: The strongest and clearest effect observed in our study was a decrease in root exudation rates of Korean pine (Pinus koraiensis Sieb. et Zucc.) and larch (Larix gmelinii (Rupr.) Kuze.) at sites located in higher latitudes. Root exudation rates were positively related to mean annual temperature, mean annual precipitation, and negatively related to soil total organic carbon. Conclusions: Root exudation in coniferous species decreased at sites located in higher latitudes. Despite differences in root exudation rate among sites located at different latitudes and species with suitable variation in root morphological traits and environmental factors, we could not identify consistent influencing factors on root exudation rates.
3
Tang, Lanlan, Ming Zhan, Chunhui Shang, Jiayi Yuan, Yibing Wan e Mingguang Qin. "Dynamics of root exuded carbon and its relationships with root traits of rapeseed and wheat". Plant, Soil and Environment 67, No. 6 (21 maggio 2021): 317–23. http://dx.doi.org/10.17221/561/2020-pse.
Abstract (sommario):
Quantifying carbon in root exudates and exploring their influencing factors are essential to understand soil organic carbon dynamics in cropland. A pot experiment was carried out to explore quantitative relations between root exuded carbon and root traits in wheat and rapeseed. The result showed that rapeseed had a similar pattern in root carbon exudation intensity (EI) as the wheat, but its EI per plant was obviously higher than that in wheat. Rapeseed plants had higher EI per root biomass than wheat plants in the early growth period but lower in the late growth period. EI per root biomass in both crops had significant exponential relationships with the specific root length (RL), surface area (RSA), volume (RV), root C/N ratio and root soluble sugar content. However, EI per plant of both crops had a markedly quadratic relationship with RL, RSA, RV and root biomass. During the whole growth period, the rapeseed had cumulative root carbon exudation of 14.09 g/plant, which was almost twice of that in the wheat plant. Root traits had close relations to root carbon exudation in both crops. Quantitative regression models between them could be referred to estimate root C exudation in rapeseed and wheat farmland.
4
Akatsuki, Maiko, e Naoki Makita. "Influence of fine root traits on in situ exudation rates in four conifers from different mycorrhizal associations". Tree Physiology 40, n. 8 (25 aprile 2020): 1071–79. http://dx.doi.org/10.1093/treephys/tpaa051.
Abstract (sommario):
Abstract Plant roots can exude organic compounds into the soil that are useful for plant survival because they can degrade microorganisms around the roots and enhance allelopathy against other plant invasions. We developed a method to collect carbon (C) exudation on a small scale from tree fine roots by C-free filter traps. We quantified total C through root exudation in four conifers from different microbial symbiotic groups (ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM)) in a cool-temperate forest in Japan. We determined the relationship of mass-based exudation rate from three diameter classes (<0.5, 0.5–1.0, and 1.0–2.5 mm) of the intact root system with root traits such as morphological traits including root diameter, specific root length (SRL), specific root area (SRA), root tissue density (RTD) and chemical traits including root nitrogen (N) content and C/N. Across species, the mass-based root exudation rate was found to correlate with diameter, SRA, RTD, N and C/N. When comparing mycorrhizal types, there were significant relationships between the exudation and diameter, SRL, SRA, root N and C/N in ECM species; however, these were not significant in AM species. Our results show that relationships between in situ root exudation and every measured trait of morphology and chemistry were strongly driven by ECM roots and not by AM roots. These differences might explain the fact that ECM roots in this study potentially covaried by optimizing the exudation and root morphology in forest trees, while exudation in AM roots did not change with changes in root morphology. In addition, the contrasting results may be attributable to the effect of degree and position of ECM and AM colonization in fine root system. Differences in fine root exudation relationships to root morphology for the two types of mycorrhizae will help us better understand the underlying mechanisms of belowground C allocation in forest ecosystems.
5
Li, Zuwang, Zhi Liu, Guoqiang Gao, Xinlei Yang e Jiacun Gu. "Shift from Acquisitive to Conservative Root Resource Acquisition Strategy Associated with Increasing Tree Age: A Case Study of Fraxinus mandshurica". Forests 12, n. 12 (17 dicembre 2021): 1797. http://dx.doi.org/10.3390/f12121797.
Abstract (sommario):
Tree age has an important effect on the form and function of fine roots. Previous studies have focused on the variations in root morphological and chemical traits among tree ages, while less attention has been given to the physiological traits, impeding a full understanding of the relationship between root resource acquisition strategy and tree age. Here, we measured root morphological (diameter, specific root length, specific root area and tissue density), chemical (nitrogen concentration) and physiological (respiration and exudation rate) traits of young, middle-aged and mature trees of Fraxinus mandshurica in a temperate secondary forest in northeastern China. Our overall aim was to determine how root traits and related resource acquisition strategy change with tree age. The results showed that from young to mature trees, root diameter gradually increased, but specific root length, specific root area, root nitrogen concentration, respiration and exudation rates all decreased, and the significant differences were mainly found between young and mature trees. Pearson’s correlation analysis revealed that the relationships of root respiration and exudation rates to root morphological and chemical traits depended on tree age and the specific traits examined, but these correlations were all significant except for root tissue density when the data were pooled across all tree age classes. Principal component analysis (PCA) showed that the conservative traits represented by root diameter, and the acquisitive traits such as root respiration and exudation rates and related morphological and chemical traits, occupied two ends of the first axis, respectively, while root tissue density occupied one end of the second axis, partially confirming the conceptual framework of “root economics space”. Standardized major axis (SMA) analysis of root exudation and respiration rates showed that young trees allocated more root carbon flux to the formation of root exudation, compared to middle-aged and mature trees. Our findings suggest that root resource acquisition strategy in F. mandshurica appears to shift from an absorptive to conservative strategy associated with increasing tree age, which may have substantial consequences for individual growth and interspecific competition, as well as belowground carbon allocation in ecosystems.
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Ataka, Mioko, Lijuan Sun, Tatsuro Nakaji, Ayumi Katayama e Tsutom Hiura. "Five-year nitrogen addition affects fine root exudation and its correlation with root respiration in a dominant species, Quercus crispula, of a cool temperate forest, Japan". Tree Physiology 40, n. 3 (24 gennaio 2020): 367–76. http://dx.doi.org/10.1093/treephys/tpz143.
Abstract (sommario):
Abstract In forest ecosystems, fine root respiration directly contributes to belowground carbon (C) cycling. Exudation from fine roots indirectly affects C cycling via enhanced microbial decomposition of soil organic matter. Although these root-derived C fluxes are essential components of belowground C cycling, how nitrogen (N) addition affects these fluxes and their correlations remains unclear. In this study, fine root exudation, respiration and chemical/morphological traits were measured in a dominant canopy species, Quercus crispula Blume, found in a cool temperate forest, the Tomakomai Experimental Forest, Hokkaido University, which has undergone 5-year N addition. Soil-dissolved organic carbon (DOC) was also measured in both bulk and rhizosphere soils to evaluate the impact of fine root exudation on soil C cycling. Compared with a control plot with no N treatment, fine roots in the N addition plot exhibited larger diameters and higher N concentrations, but lower specific root lengths and areas. On a root-weight basis, respiration was not different between plots, but exudation was slightly higher under N addition. On a root-area basis, exudation was significantly higher in the N addition plot. Additionally, differences in DOC between rhizosphere and bulk soils were two times higher in the N addition plot than the control plot. Although fine root respiration was positively correlated with exudation in both the control and N addition plots, the ratio of exudation C to respiration C decreased after 5-year N addition. Nitrogen addition also affected absolute C allocation to fine root exudation and changed the C allocation strategy between exudation and respiration fluxes. These findings will help enhance predictions of belowground C allocation and C cycling under N-rich conditions in the future.
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Wen, Zhihui, Philip J. White, Jianbo Shen e Hans Lambers. "Linking root exudation to belowground economic traits for resource acquisition". New Phytologist 233, n. 4 (4 dicembre 2021): 1620–35. http://dx.doi.org/10.1111/nph.17854.
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Miller, Sarah B., Adam L. Heuberger, Corey D. Broeckling e Courtney E. Jahn. "Non-Targeted Metabolomics Reveals Sorghum Rhizosphere-Associated Exudates are Influenced by the Belowground Interaction of Substrate and Sorghum Genotype". International Journal of Molecular Sciences 20, n. 2 (19 gennaio 2019): 431. http://dx.doi.org/10.3390/ijms20020431.
Abstract (sommario):
Root exudation is an important plant process by which roots release small molecules into the rhizosphere that serve in overall plant functioning. Yet, there is a major gap in our knowledge in translating plant root exudation in artificial systems (i.e., hydroponics, sterile media) to crops, specifically for soils expected in field conditions. Sorghum (Sorghum bicolor L. Moench) root exudation was determined using both ultra-performance liquid chromatography and gas chromatography mass spectrometry-based non-targeted metabolomics to evaluate variation in exudate composition of two sorghum genotypes among three substrates (sand, clay, and soil). Above and belowground plant traits were measured to determine the interaction between sorghum genotype and belowground substrate. Plant growth and quantitative exudate composition were found to vary largely by substrate. Two types of changes to rhizosphere metabolites were observed: rhizosphere-enhanced metabolites (REMs) and rhizosphere-abated metabolites (RAMs). More REMs and RAMs were detected in sand and clay substrates compared to the soil substrate. This study demonstrates that belowground substrate influences the root exudate profile in sorghum, and that two sorghum genotypes exuded metabolites at different magnitudes. However, metabolite identification remains a major bottleneck in non-targeted metabolite profiling of the rhizosphere.
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Cardenas, Julian, Fernando Santa e Eva Kaštovská. "The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry". Land 10, n. 8 (11 agosto 2021): 840. http://dx.doi.org/10.3390/land10080840.
Abstract (sommario):
The rhizosphere is a hot spot of soil microbial activity and is largely fed by root exudation. The carbon (C) exudation flux, coupled with plant growth, is considered a strategy of plants to facilitate nutrient uptake. C exudation is accompanied by a release of nutrients. Nitrogen (N) and phosphorus (P) co-limit the productivity of the plant-microbial system. Therefore, the C:N:P stoichiometry of exudates should be linked to plant nutrient economies, plant functional traits (PFT) and soil nutrient availability. We aimed to identify the strongest links in C:N:P stoichiometry among all rhizosphere components. A total of eight grass species (from conservative to exploitative) were grown in pots under two different soil C:nutrient conditions for a month. As a result, a wide gradient of plant–microbial–soil interactions were created. A total of 43 variables of plants, exudates, microbial and soil C:N:P stoichiometry, and PFTs were evaluated. The variables were merged into four groups in a network analysis, allowing us to identify the strongest connections among the variables and the biological meaning of these groups. The plant–soil interactions were shaped by soil N availability. Faster-growing plants were associated with lower amounts of mineral N (and P) in the soil solution, inducing a stronger competition for N with microorganisms in the rhizosphere compared to slower-growing plants. The plants responded by enhancing their N use efficiency and root:shoot ratio, and they reduced N losses via exudation. Root growth was supported either by reallocated foliar reserves or by enhanced ammonium uptake, which connected the specific leaf area (SLA) to the mineral N availability in the soil. Rapid plant growth enhanced the exudation flux. The exudates were rich in C and P relative to N compounds and served to release surplus metabolic products. The exudate C:N:P stoichiometry and soil N availability combined to shape the microbial stoichiometry, and N and P mining. In conclusion, the exudate flux and its C:N:P stoichiometry reflected the plant growth rate and nutrient constraints with a high degree of reliability. Furthermore, it mediated the plant–microbial interactions in the rhizosphere.
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Marschmann, Gianna L., Jinyun Tang, Kateryna Zhalnina, Ulas Karaoz, Heejung Cho, Beatrice Le, Jennifer Pett-Ridge e Eoin L. Brodie. "Predictions of rhizosphere microbiome dynamics with a genome-informed and trait-based energy budget model". Nature Microbiology 9, n. 2 (5 febbraio 2024): 421–33. http://dx.doi.org/10.1038/s41564-023-01582-w.
Abstract (sommario):
AbstractSoil microbiomes are highly diverse, and to improve their representation in biogeochemical models, microbial genome data can be leveraged to infer key functional traits. By integrating genome-inferred traits into a theory-based hierarchical framework, emergent behaviour arising from interactions of individual traits can be predicted. Here we combine theory-driven predictions of substrate uptake kinetics with a genome-informed trait-based dynamic energy budget model to predict emergent life-history traits and trade-offs in soil bacteria. When applied to a plant microbiome system, the model accurately predicted distinct substrate-acquisition strategies that aligned with observations, uncovering resource-dependent trade-offs between microbial growth rate and efficiency. For instance, inherently slower-growing microorganisms, favoured by organic acid exudation at later plant growth stages, exhibited enhanced carbon use efficiency (yield) without sacrificing growth rate (power). This insight has implications for retaining plant root-derived carbon in soils and highlights the power of data-driven, trait-based approaches for improving microbial representation in biogeochemical models.
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Tato, Liliana, Monirul Islam, Tanja Mimmo, Graziano Zocchi e Gianpiero Vigani. "Temporal Responses to Direct and Induced Iron Deficiency in Parietaria judaica". Agronomy 10, n. 7 (18 luglio 2020): 1037. http://dx.doi.org/10.3390/agronomy10071037.
Abstract (sommario):
Parietaria judaica grows in highly calcareous environments, overcoming the low bioavailability of Fe caused by elevated pH. The aim of this work was to investigate the temporal dynamics of root exudation of P. judaica under Fe deficiency conditions. As high concentrations of bicarbonate and Ca2+ in calcareous soils interfere with the general plant mineral nutrition, two different alkaline growing conditions were applied to distinguish the effects due to the high pH from the responses induced by the presence of high calcium carbonate concentrations. Growth parameters and physiological responses were analyzed during a 7 day time course—shoot and root biomass, chlorophyll and flavonoid contents in leaves, root accumulation, and exudation of organic acids and phenolics were determined. Different responses were found in plants grown in the presence of bicarbonate and in the presence of an organic pH buffer, revealing a time- and condition-dependent response of P. judaica and suggesting a stronger stress in the buffer treatment. The high tolerance to alkaline conditions may be related to an earlier and greater exudation rate of phenolics, as well as to the synergistic effect of phenolics and carboxylic acids in root exudates in the late response. The identification of the main functional traits involved in tolerance to low Fe availability in a wild species could offer crucial inputs for breeding programs for application to crop species.
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Salim, Mohammad, Yinglong Chen, Zakaria M. Solaiman e Kadambot H. M. Siddique. "Phosphorus Application Enhances Root Traits, Root Exudation, Phosphorus Use Efficiency, and Seed Yield of Soybean Genotypes". Plants 12, n. 5 (1 marzo 2023): 1110. http://dx.doi.org/10.3390/plants12051110.
Abstract (sommario):
Phosphorus (P) is a vital macronutrient required for soybean growth and development but is a finite resource in agriculture worldwide. Low inorganic P availability in soil is often a significant constraint for soybean production. However, little is known about the response of P supply on agronomic, root morphology, and physiological mechanisms of contrasting soybean genotypes at various growth stages and the possible effects of different P on soybean yield and yield components. Therefore, we conducted two concurrent experiments using the soil-filled pots with six genotypes (deep-root system: PI 647960, PI 398595, PI 561271, PI 654356; and shallow-root system: PI 595362, PI 597387) and two P levels [0 (P0) and 60 (P60) mg P kg−1 dry soil] and deep PVC columns with two genotypes (PI 561271 and PI 595362) and three P levels [0 (P0), 60 (P60), and 120 (P120) mg P kg−1 dry soil] in a temperature-controlled glasshouse. The genotype × P level interaction showed that increased higher P supply increased leaf area, shoot and root dry weights, total root length, shoot, root, and seed P concentrations and contents, P use efficiency (PUE), root exudation, and seed yield at different growth stages in both experiments. At the vegetative stage (Experiment 1), shallow-rooted genotypes with shorter life cycles had more root dry weight (39%) and total root length (38%) than deep-rooted genotypes with longer life cycles under different P levels. Genotype PI 654356 produced significantly higher (22% more) total carboxylates than PI 647960 and PI 597387 under P60 but not at P0. Total carboxylates positively correlated with root dry weight, total root length, shoot and root P contents, and physiological PUE. The deep-rooted genotypes (PI 398595, PI 647960, PI 654356, and PI 561271) had the highest PUE and root P contents. In Experiment 2, at the flowering stage, genotype PI 561271 had the greatest leaf area (202%), shoot dry weight (113%), root dry weight (143%), and root length (83%) relative to the short-duration, shallow-rooted genotype PI 595362 with external P applied (P60 and P120), with similar trends at maturity. PI 595362 had a greater proportion of carboxylates as malonate (248%), malate (58%), and total carboxylates (82%) than PI 561271 under P60 and P120 but no differences at P0. At maturity, the deep-rooted genotype PI 561271 had greater shoot, root, and seed P contents and PUE than the shallow-rooted genotype PI 595362 under increased P rates but no differences at P0. Further, the genotype PI 561271 had higher shoot (53%), root (165%), and seed yield (47%) than PI 595362 with P60 and P120 than P0. Therefore, inorganic P application enhances plant resistance to the soil P pool and maintains high soybean biomass production and seed yield.
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MacAlister, Dunja, A. Muthama Muasya e Samson B. M. Chimphango. "Linking root traits to superior phosphorus uptake and utilisation efficiency in three Fabales in the Core Cape Subregion, South Africa". Functional Plant Biology 45, n. 7 (2018): 760. http://dx.doi.org/10.1071/fp17209.
Abstract (sommario):
In the low-P soil of the fynbos biome, plants have evolved several morphological and physiological P acquisition and use mechanisms, leading to variable uptake and use efficiencies. We expected that plants grown in low-P soils would exhibit greater P acquisition traits and hypothesised that Aspalathus linearis (Burm. f.) R. Dahlgren, a cluster-root-forming species adapted to drier and infertile soils, would be the most efficient at P acquisition compared with other species. Three fynbos Fabales species were studied: A. linearis and Podalyria calyptrata (Retz.) Willd, both legumes, and Polygala myrtifolia L., a nonlegume. A potted experiment was conducted where the species were grown in two soil types with high P (41.18 mg kg–1) and low P (9.79 mg kg–1). At harvest, biomass accumulation, foliar nutrients and P acquisition mechanisms were assessed. Polygala myrtifolia developed a root system with greater specific root length, root hair width and an average root diameter that exuded a greater amount of citrate and, contrary to the hypothesis, exhibited greater whole-plant P uptake efficiency. However, P. calyptrata had higher P use efficiency, influenced by N availability through N2 fixation. Specific root length, root length and root : shoot ratio were promising morphological traits for efficient foraging of P, whereas acid phosphatase exudation was the best physiological trait for solubilisation of P.
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Wouterlood, Madeleine, Hans Lambers e Erik J. Veneklaas. "Plant phosphorus status has a limited influence on the concentration of phosphorus-mobilising carboxylates in the rhizosphere of chickpea". Functional Plant Biology 32, n. 2 (2005): 153. http://dx.doi.org/10.1071/fp04084.
Abstract (sommario):
Two experiments were conducted to investigate whether carboxylate exudation by chickpea (Cicer arietinum L.) is a response to phosphorus (P) deficiency or a constitutive trait. The effect of P supply on carboxylate concentrations in the plant and in the rhizosphere of chickpea cultivar Heera was studied in a sand culture. Plants were grown in pots supplied with 200 mL of solution containing 0–500 μm P every 3 d. Malonate was the main carboxylate exuded, and the main carboxylate in roots; shoots contained mainly citrate and malate. Contrary to what has been reported for other species, carboxylate concentrations in the rhizosphere decreased only slightly at high P supply, but they were still substantial. The effect of P supply on the rate of exudation was studied in a split-root sand culture. Root systems were split into two pots, one root half received no P and the other half received 200 mL of solution containing 0–500 μm P. The rhizosphere of both root halves contained similar concentrations of carboxylates, even when the plants received a different supply of P. Our results indicate that carboxylate exudation is determined by internal P rather than external factors. The fact that chickpea roots always exude carboxylates indicates that exudation in this species is largely constitutive.
15
Shaposhnikov, A. I., A. A. Belimov, T. S. Azarova, O. K. Strunnikova, N. A. Vishnevskaya, N. I. Vorobyov, O. S. Yuzikhin, L. A. Bespalova e I. A. Tikhonovich. "Relationship between the Composition of Root Exsudates and the Efficiency of Interaction of Wheat Plants with Microorganisms". Прикладная биохимия и микробиология 59, n. 3 (1 maggio 2023): 260–74. http://dx.doi.org/10.31857/s0555109923030170.
Abstract (sommario):
Plant roots secrete various organic substances into the rhizosphere, which are a source of nutrition for microorganisms and largely determine the nature of plant-microbe interactions. The composition of the main fractions of root exudates in ten modern varieties of wheat was determined: amino acids, organic acids and sugars. Reliable qualitative and quantitative differences between varieties for individual components of exudates were revealed, which determined the peculiarities of cultivar clustering on this trait. Relationships between exudation and the effectiveness of plant interaction with the growth-promoting rhizobacterium Pseudomonas fluorescens SPB2137 and the phytopathogenic fungus Fusarium culmorum 30 in laboratory systems, as well as with the resistance of varieties to diseases in the field, were found. The number of P. fluorescens SPB2137 in the root zone positively correlated with the amount of many amino acids, as well as maltose, secreted by the roots. The stimulating effect of rhizobacteria on root growth positively correlated with the amount of released glucose and melibiose. The relationship between the nature of root exudation and root colonization or the susceptibility of varieties to F. culmorum 30 was not found. The analysis of correlations between the incidence of wheat varieties in the field and the intensity of exudation of certain substances, as well as with the biocomposition index of amino acid exudation, was carried out. The role of root exudate components in the formation of effective plant-microbial systems is discussed.
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Krishnapriya, Vengavasi, e Renu Pandey. "Root exudation index: screening organic acid exudation and phosphorus acquisition efficiency in soybean genotypes". Crop and Pasture Science 67, n. 10 (2016): 1096. http://dx.doi.org/10.1071/cp15329.
Abstract (sommario):
High-molecular-weight secretory proteins and low-molecular-weight exudates (carboxylates, phenols, free amino acids and sugars) released from roots of soybean (Glycine max (L.) Merr.) differentially influence genotypic phosphorus (P) acquisition efficiency (PAE). We hypothesised that genotypes with higher root exudation potential would exhibit enhanced P acquisition, and screened 116 diverse soybean genotypes by labelling shoots with 14CO2. A root exudation index (REI) derived from total 14C in the root exudate at sufficient (250 μm) and low (4 μm) P levels was used to classify genotypes for PAE. Genotypes with REI >2.25 exhibited significantly higher exudation at low than at sufficient P, which in turn increased PAE. Under low P availability, efficient genotypes exude a greater quantity of organic compounds into the rhizosphere. This increases P availability to meet the crop requirement, enabling the crop to produce consistent biomass and seed yield with reduced fertiliser addition. Such maintenance of growth and yield potential by mining the inherent soil P is a favourable trait in genotypes, reducing dependence on P fertilisers. Measuring REI at seedling stage to select P-efficient plants accelerates the screening process by accommodating large numbers of genotypes.
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Tapia-Valdebenito, Daisy, León A. Bravo Ramirez, Patricio Arce–Johnson e Ana Gutiérrez-Moraga. "Salt tolerance traits in Deschampsia antarctica Desv." Antarctic Science 28, n. 6 (8 agosto 2016): 462–72. http://dx.doi.org/10.1017/s0954102016000249.
Abstract (sommario):
AbstractDeschampsia antarctica Desv. (Poaceae) grows in coastal habitats in the Maritime Antarctic where it is often exposed to sea spray. Salt crystals have been observed on the surface of leaves in plants treated with high NaCl. We investigated if D. antarctica is a salt tolerant species that allows sodium ions to diffuse into the root where a salt overly sensitive (SOS) system extrudes Na+ from root cells and facilitates its movement through the xylem up to the leaves. Leaf epidermis, physiological parameters and sodium transporters in D. antarctica plants exposed to NaCl were studied over 21 days. Epidermal scanning electron microscopy showed trichome induction in the leaves of salt treated plants. In addition, salt treated plants showed increased sodium and proline levels with a concomitant increased expression of SOS genes (1 and 3). These results indicate that Na+ is taken up by the roots of D. antarctica and transported to the leaves. The sodium flux may be controlled by SOS1 activity. Up-regulation of the SOS1 gene may be involved in the increased sodium levels observed in the leaves of salt treated plants. Trichomes may also be involved in sodium exudation through the leaves under saline conditions.
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White, Philip J. "Root traits benefitting crop production in environments with limited water and nutrient availability". Annals of Botany 124, n. 6 (10 ottobre 2019): 883–90. http://dx.doi.org/10.1093/aob/mcz162.
Abstract (sommario):
Abstract Background Breeding for advantageous root traits will play a fundamental role in improving the efficiency of water and nutrient acquisition, closing yield gaps, and underpinning the ‘Evergreen Revolution’ that must match crop production with human demand. Scope This preface provides an overview of a Special Issue of Annals of Botany on ‘Root traits benefitting crop production in environments with limited water and nutrient availability’. The first papers in the Special Issue examine how breeding for reduced shoot stature and greater harvest index during the Green Revolution affected root system architecture. It is observed that reduced plant height and root architecture are inherited independently and can be improved simultaneously to increase the acquisition and utilization of carbon, water and mineral nutrients. These insights are followed by papers examining beneficial root traits for resource acquisition in environments with limited water or nutrient availability, such as deep rooting, control of hydraulic conductivity, formation of aerenchyma, proliferation of lateral roots and root hairs, foraging of nutrient-rich patches, manipulation of rhizosphere pH and the exudation of low molecular weight organic solutes. The Special Issue concludes with papers exploring the interactions of plant roots and microorganisms, highlighting the need for plants to control the symbiotic relationships between mycorrhizal fungi and rhizobia to achieve maximal growth, and the roles of plants and microbes in the modification and development of soils.
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de Souza Campos, Pedro M., Sebastián Meier, Arturo Morales, Laura Lavanderos, Javiera Nahuelcura, Antonieta Ruiz, Álvaro López-García e Alex Seguel. "New Insights into the Phosphorus Acquisition Capacity of Chilean Lowland Quinoa Roots Grown under Low Phosphorus Availability". Plants 11, n. 22 (10 novembre 2022): 3043. http://dx.doi.org/10.3390/plants11223043.
Abstract (sommario):
Reducing phosphate fertilizer inputs while increasing food nutritional quality has been posited as a major challenge to decrease human undernourishment and ensure food security. In this context, quinoa has emerged as a promising crop due to its ability to tolerate different stress conditions and grow in marginal soils with low nutrient content, in addition to the exceptional nutritional quality of its grains. However, there is scarce information about the phosphorus acquisition capacity of quinoa roots. This work aimed to provide new insights into P acquisition and functional root traits, such as root biomass, rhizosphere pH, carboxylate exudation, and acid phosphatase activity of thirty quinoa genotypes grown under P limiting conditions (7 mg P kg−1). Significant genotypic variation was observed among genotypes, with average P accumulation ranging from 1.2 to 11.8 mg. The shoot biomass production varied more than 14 times among genotypes and was correlated with the P accumulation on shoots (r = 0.91). Despite showing high variability in root traits, only root biomass production highly correlated with P acquisition (r = 0.77), suggesting that root growth/morphology rather than the measured biochemical activity possesses a critical role in the P nutrition of quinoa.
20
Yin, Huajun, Juan Xiao, Yufei Li, Zhi Chen, Xinying Cheng, Chunzhang Zhao e Qing Liu. "Warming effects on root morphological and physiological traits: The potential consequences on soil C dynamics as altered root exudation". Agricultural and Forest Meteorology 180 (ottobre 2013): 287–96. http://dx.doi.org/10.1016/j.agrformet.2013.06.016.
21
Ahmed, Mutez A., Eva Kroener, Maire Holz, Mohsen Zarebanadkouki e Andrea Carminati. "Mucilage exudation facilitates root water uptake in dry soils". Functional Plant Biology 41, n. 11 (2014): 1129. http://dx.doi.org/10.1071/fp13330.
Abstract (sommario):
As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere was wetter than the bulk soil during root water uptake. We hypothesise that the increased water content in the rhizosphere was caused by mucilage exuded by roots. It is probably that the higher water content in the rhizosphere results in higher hydraulic conductivity of the root–soil interface. In this case, mucilage exudation would favour the uptake of water in dry soils. To test this hypothesis, we covered a suction cup, referred to as an artificial root, with mucilage. We placed it in soil with a water content of 0.03 cm3 cm–3, and used the root pressure probe technique to measure the hydraulic conductivity of the root–soil continuum. The results were compared with measurements with roots not covered with mucilage. The root pressure relaxation curves were fitted with a model of root water uptake including rhizosphere dynamics. The results demonstrated that when mucilage is added to the root surface, it keeps the soil near the roots wet and hydraulically well conductive, facilitating the water flow from dry soils towards the root surface. Mucilage exudation seems to be an optimal plant trait that favours the capture of water when water is scarce.
22
Egamberdieva, Dilfuza, Farkhod Eshboev, Oybek Shukurov, Burak Alaylar e Naveen Kumar Arora. "Bacterial Bioprotectants: Biocontrol Traits and Induced Resistance to Phytopathogens". Microbiology Research 14, n. 2 (22 maggio 2023): 689–703. http://dx.doi.org/10.3390/microbiolres14020049.
Abstract (sommario):
Plant growth and nutrition are adversely affected by various factors such as water stress, high temperature, and plant pathogens. Plant-associated microbes play a vital role in the growth and development of their hosts under biotic and abiotic stresses. The use of a rhizosphere microbiome for plant growth stimulation and the biological control of fungal disease can lead to improved crop productivity. Mechanisms used by plant-growth-promoting rhizobacteria (PGPR) to protect plants from soilborne pathogens include antibiosis, the production of lytic enzymes, indole-3 acetic acid production, decreasing ethylene levels by secreting 1-aminocyclopropane-1-carboxylate deaminase, competition for nutrients and niches, parasitism and induced systemic resistance. In this review, we emphasize the biological control of plant pathogens by root-associated microbes and discuss traits involved in pathogen reduction. Future research should focus on the effect of root exudation on plant–pathogen interactions under various abiotic factors. Moreover, the development of microbial fungicides with longer shelf lives will help farmers to opt for organic agriculture, reducing the use of chemical fertilizers. This trend is expected to drive the adoption of biological control methods in agriculture. The future prospects for the biological control of plant diseases are bright and are expected to play an increasingly important role in sustainable agriculture.
23
Parra-Almuna, Leyla, Sofía Pontigo, Antonieta Ruiz, Felipe González, Nuria Ferrol, María de la Luz Mora e Paula Cartes. "Dissecting the Roles of Phosphorus Use Efficiency, Organic Acid Anions, and Aluminum-Responsive Genes under Aluminum Toxicity and Phosphorus Deficiency in Ryegrass Plants". Plants 13, n. 7 (23 marzo 2024): 929. http://dx.doi.org/10.3390/plants13070929.
Abstract (sommario):
Aluminum (Al) toxicity and phosphorus (P) deficiency are widely recognized as major constraints to agricultural productivity in acidic soils. Under this scenario, the development of ryegrass plants with enhanced P use efficiency and Al resistance is a promising approach by which to maintain pasture production. In this study, we assessed the contribution of growth traits, P efficiency, organic acid anion (OA) exudation, and the expression of Al-responsive genes in improving tolerance to concurrent low-P and Al stress in ryegrass (Lolium perenne L.). Ryegrass plants were hydroponically grown under optimal (0.1 mM) or low-P (0.01 mM) conditions for 21 days, and further supplied with Al (0 and 0.2 mM) for 3 h, 24 h and 7 days. Accordingly, higher Al accumulation in the roots and lower Al translocation to the shoots were found in ryegrass exposed to both stresses. Aluminum toxicity and P limitation did not change the OA exudation pattern exhibited by roots. However, an improvement in the root growth traits and P accumulation was found, suggesting an enhancement in Al tolerance and P efficiency under combined Al and low-P stress. Al-responsive genes were highly upregulated by Al stress and P limitation, and also closely related to P utilization efficiency. Overall, our results provide evidence of the specific strategies used by ryegrass to co-adapt to multiple stresses in acid soils.
24
Li, Xun, Jinlong Dong, Wenying Chu, Yujiao Chen e Zengqiang Duan. "The relationship between root exudation properties and root morphological traits of cucumber grown under different nitrogen supplies and atmospheric CO2 concentrations". Plant and Soil 425, n. 1-2 (19 febbraio 2018): 415–32. http://dx.doi.org/10.1007/s11104-017-3555-8.
25
Klamer, Florian, Florian Vogel, Xuelian Li, Hinrich Bremer, Günter Neumann, Benjamin Neuhäuser, Frank Hochholdinger e Uwe Ludewig. "Estimating the importance of maize root hairs in low phosphorus conditions and under drought". Annals of Botany 124, n. 6 (12 febbraio 2019): 961–68. http://dx.doi.org/10.1093/aob/mcz011.
Abstract (sommario):
Abstract Background and Aims Root hairs are single-cell extensions of the epidermis that face into the soil and increase the root–soil contact surface. Root hairs enlarge the rhizosphere radially and are very important for taking up water and sparingly soluble nutrients, such as the poorly soil-mobile phosphate. In order to quantify the importance of root hairs for maize, a mutant and the corresponding wild type were compared. Methods The rth2 maize mutant with very short root hairs was assayed for growth and phosphorus (P) acquisition in a slightly alkaline soil with low P and limited water supply in the absence of mycorrhization and with ample P supply. Key Results Root and shoot growth was additively impaired under P deficiency and drought. Internal P concentrations declined with reduced water and P supply, whereas micronutrients (iron, zinc) were little affected. The very short root hairs in rth2 did not affect internal P concentrations, but the P content of juvenile plants was halved under combined stress. The rth2 plants had more fine roots and increased specific root length, but P mobilization traits (root organic carbon and phosphatase exudation) differed little. Conclusions The results confirm the importance of root hairs for maize P uptake and content, but not for internal P concentrations. Furthermore, the performance of root hair mutants may be biased by secondary effects, such as altered root growth.
26
Yan, Xiaolong, Hong Liao, Steve E. Beebe, Matthew W. Blair e Jonathan P. Lynch. "QTL mapping of root hair and acid exudation traits and their relationship to phosphorus uptake in common bean". Plant and Soil 265, n. 1-2 (agosto 2004): 17–29. http://dx.doi.org/10.1007/s11104-005-0693-1.
27
Palmer, Antony J., Alison Baker e Stephen P. Muench. "The varied functions of aluminium-activated malate transporters–much more than aluminium resistance". Biochemical Society Transactions 44, n. 3 (9 giugno 2016): 856–62. http://dx.doi.org/10.1042/bst20160027.
Abstract (sommario):
The ALMT (aluminium-activated malate transporter) family comprises a functionally diverse but structurally similar group of ion channels. They are found ubiquitously in plant species, expressed throughout different tissues, and located in either the plasma membrane or tonoplast. The first family member identified was TaALMT1, discovered in wheat root tips, which was found to be involved in aluminium resistance by means of malate exudation into the soil. However, since this discovery other family members have been shown to have many other functions such as roles in stomatal opening, general anionic homoeostasis, and in economically valuable traits such as fruit flavour. Recent evidence has also shown that ALMT proteins can act as key molecular actors in GABA (γ-aminobutyric acid) signalling, the first evidence that GABA can act as a signal transducer in plants.
28
Anonymous. "Peer review report 1 On “Warming effects on root morphological and physiological traits: the potential consequences on soil C dynamics as altered root exudation”". Agricultural and Forest Meteorology 201 (gennaio 2015): 261–62. http://dx.doi.org/10.1016/j.agrformet.2015.08.070.
29
Guyonnet, Julien P., Amélie A. M. Cantarel, Laurent Simon e Feth el Zahar Haichar. "Root exudation rate as functional trait involved in plant nutrient‐use strategy classification". Ecology and Evolution 8, n. 16 (30 luglio 2018): 8573–81. http://dx.doi.org/10.1002/ece3.4383.
30
Agathokleous, Evgenios, Zhaozhong Feng, Elina Oksanen, Pierre Sicard, Qi Wang, Costas J. Saitanis, Valda Araminiene et al. "Ozone affects plant, insect, and soil microbial communities: A threat to terrestrial ecosystems and biodiversity". Science Advances 6, n. 33 (agosto 2020): eabc1176. http://dx.doi.org/10.1126/sciadv.abc1176.
Abstract (sommario):
Elevated tropospheric ozone concentrations induce adverse effects in plants. We reviewed how ozone affects (i) the composition and diversity of plant communities by affecting key physiological traits; (ii) foliar chemistry and the emission of volatiles, thereby affecting plant-plant competition, plant-insect interactions, and the composition of insect communities; and (iii) plant-soil-microbe interactions and the composition of soil communities by disrupting plant litterfall and altering root exudation, soil enzymatic activities, decomposition, and nutrient cycling. The community composition of soil microbes is consequently changed, and alpha diversity is often reduced. The effects depend on the environment and vary across space and time. We suggest that Atlantic islands in the Northern Hemisphere, the Mediterranean Basin, equatorial Africa, Ethiopia, the Indian coastline, the Himalayan region, southern Asia, and Japan have high endemic richness at high ozone risk by 2100.
31
Sun, Lijuan, Mioko Ataka, Mengguang Han, Yunfeng Han, Dayong Gan, Tianle Xu, Yanpei Guo e Biao Zhu. "Root exudation as a major competitive fine‐root functional trait of 18 coexisting species in a subtropical forest". New Phytologist 229, n. 1 (2 settembre 2020): 259–71. http://dx.doi.org/10.1111/nph.16865.
32
Yang, Xiaoxia, Rui Liu, Miao Jing, Ningning Zhang, Cuiying Liu e Jiakun Yan. "Variation of Root Soluble Sugar and Starch Response to Drought Stress in Foxtail Millet". Agronomy 13, n. 2 (26 gennaio 2023): 359. http://dx.doi.org/10.3390/agronomy13020359.
Abstract (sommario):
Foxtail millet is an important crop in Northwest China; however, the mechanism responsible for regulating root adjustment, including water uptake, sugar transport, or metabolism, in foxtail millet remains unclear. Two millet cultivars (the drought-resistant Yugu1 [YG] and the drought-sensitive An04 [An]) were used to detect physiological, molecular, and agronomic traits under two different soil water conditions. Water use efficiency increased by 18.4% and 63.2% under drought stress in An and YG, respectively. Under drought stress, YG and An root exudation (RE) decreased by 66.7% and 89.0%, the photosynthesis rate decreased by 34.3% and 61.8%, and the grain yield decreased by 40.6% and 62.6%, respectively. An contained a high ratio of soluble sugar to starch, whereas YG remained consistent. RNA-seq data showed a lower expression of beta-amylase 2 in YG than in An. The expression levels of three SWEET genes involved in sugar transport and four plasma membrane intrinsic protein (PIP) genes were higher in YG than in An, allocating more photosynthetic sugar to the roots to prevent a significant elevation in the ratio of soluble sugar to starch. The high expression levels of SiPIPs also enhanced root water transport capacity. Based on the above-mentioned adaptations, millet maintains high RE, stomatal conductance, and net photosynthetic rate in drought stress conditions.
33
Lv, Chunhua, Chuankuan Wang, Yiling Li e Zhenghu Zhou. "Coordination among root exudation C, mycorrhizal colonization, and functional traits and their responses to drought in five temperate tree species". Forest Ecology and Management 546 (ottobre 2023): 121316. http://dx.doi.org/10.1016/j.foreco.2023.121316.
34
Weisskopf, Laure, Stefanie Heller e Leo Eberl. "Burkholderia Species Are Major Inhabitants of White Lupin Cluster Roots". Applied and Environmental Microbiology 77, n. 21 (9 settembre 2011): 7715–20. http://dx.doi.org/10.1128/aem.05845-11.
Abstract (sommario):
ABSTRACTThe formation of cluster roots by plants represents a highly efficient strategy for acquisition of sparingly available phosphate. This particular root type is characterized by a densely branched structure and high exudation of organic acids and protons, which are likely to influence the resident bacterial community. Until now, the identity of the bacterial populations living in cluster roots has not been investigated. We applied cultivation-dependent and cultivation-independent methods to characterize the dominant bacterial genera inhabiting the growing cluster roots of white lupin. We observed a high relative abundance ofBurkholderiaspecies (up to 58% of all isolated strains and 44% of all retrieved 16S rRNA sequences) and a significant enrichment with increasing cluster root age. Most of the sequences retrieved clustered together with known plant- or fungus-associatedBurkholderiaspecies, while only one of 98 sequences was affiliated with theBurkholderia cepaciacomplex.In vitroassays revealed thatBurkholderiastrains were much more tolerant to low pH than non-Burkholderiastrains. Moreover, many strains produced large amounts of siderophores and were able to utilize citrate and oxalate as carbon sources. These features seem to represent important traits for the successful colonization and maintenance ofBurkholderiaspecies in white lupin cluster roots.
35
Vives-Peris, Vicente, María F. López-Climent, Rosa M. Pérez-Clemente e Aurelio Gómez-Cadenas. "Root Involvement in Plant Responses to Adverse Environmental Conditions". Agronomy 10, n. 7 (1 luglio 2020): 942. http://dx.doi.org/10.3390/agronomy10070942.
Abstract (sommario):
Climate change is altering the environment in which plants grow and survive. An increase in worldwide Earth surface temperatures has been already observed, together with an increase in the intensity of other abiotic stress conditions such as water deficit, high salinity, heavy metal intoxication, etc., generating harmful conditions that destabilize agricultural systems. Stress conditions deeply affect physiological, metabolic and morphological traits of plant roots, essential organs for plant survival as they provide physical anchorage to the soil, water and nutrient uptake, mechanisms for stress avoidance, specific signals to the aerial part and to the biome in the soil, etc. However, most of the work performed until now has been mainly focused on aerial organs and tissues. In this review, we summarize the current knowledge about the effects of different abiotic stress conditions on root molecular and physiological responses. First, we revise the methods used to study these responses (omics and phenotyping techniques). Then, we will outline how environmental stress conditions trigger various signals in roots for allowing plant cells to sense and activate the adaptative responses. Later, we discuss on some of the main regulatory mechanisms controlling root adaptation to stress conditions, the interplay between hormonal regulatory pathways and the global changes on gene expression and protein homeostasis. We will present recent advances on how the root system integrates all these signals to generate different physiological responses, including changes in morphology, long distance signaling and root exudation. Finally, we will discuss the new prospects and challenges in this field.
36
Minemba, David, Deirdre B. Gleeson, Erik Veneklaas e Megan H. Ryan. "Variation in morphological and physiological root traits and organic acid exudation of three sweet potato (Ipomoea batatas) cultivars under seven phosphorus levels". Scientia Horticulturae 256 (ottobre 2019): 108572. http://dx.doi.org/10.1016/j.scienta.2019.108572.
37
Singh, Chandan Kumar, Dharmendra Singh, Shristi Sharma, Shivani Chandra, Ram Sewak Singh Tomar, Arun Kumar, K. C. Upadhyaya e Madan Pal. "Mechanistic Association of Quantitative Trait Locus with Malate Secretion in Lentil (Lens culinaris Medikus) Seedlings under Aluminium Stress". Plants 10, n. 8 (28 luglio 2021): 1541. http://dx.doi.org/10.3390/plants10081541.
Abstract (sommario):
Aluminium (Al) toxicity acts as a major delimiting factor in the productivity of many crops including lentil. To alleviate its effect, plants have evolved with Al exclusion and inclusion mechanisms. The former involves the exudation of organic acid to restrict the entry of Al3+ to the root cells while latter involves detoxification of entered Al3+ by organic acids. Al-induced secretion of organic acids from roots is a well-documented mechanism that chelates and neutralizes Al3+ toxicity. In this study, F6 recombinant inbred lines (RILs) derived from a cross between L-7903 (Al-resistant) and BM-4 (Al-sensitive) were phenotyped to assess variation in secretion levels of malate and was combined with genotypic data obtained from 10 Al-resistance linked simple sequence repeat (SSRs) markers. A major quantitative trait loci (QTL) was mapped for malate (qAlt_ma) secretion with a logarithm of odd (LOD) value of 7.7 and phenotypic variation of 60.2%.Validated SSRs associated with this major QTL will be useful in marker assisted selection programmes for improving Al resistance in lentil.
38
Mora-Córdova, Claudia Paola, Roser Tolrà, Rosa Padilla, Charlotte Poschenrieder, Marie-Helene Simard, Luis Asín, Pere Vilardell, Joan Bonany, Elisabet Claveria e Ramon Dolcet-Sanjuan. "Rhizosphere Acidification as the Main Trait Characterizing the Differential In Vitro Tolerance to Iron Chlorosis in Interspecific Pyrus Hybrids". Horticulturae 8, n. 6 (18 giugno 2022): 551. http://dx.doi.org/10.3390/horticulturae8060551.
Abstract (sommario):
Physiological responses of different interspecific Pyrus hybrids and an open pollinated Pyrus communis ‘Williams’ (Pcw) grown under in vitro culture conditions simulating lime induced chlorosis were studied. The hybrids were derived from crosses between the ‘Pyriam’ pear rootstock and four Pyrus species of the Mediterranean region, namely P. amygdaliformis Vill. (Pa), P. amygdaliformis persica Bornme. (Pap), P. communis cordata (Desv.) Hook. (Pcc), and P. elaeagrifolia Pall (Pe), all known for their higher field tolerance to iron-chlorosis than P. communis. Twenty hybrids and one open pollinated Pcw were micropropagated, and plantlets were in vitro characterized for their physiological responses to iron-deficiency conditions. Rooted plantlets were transferred to a culture medium with 2 µM Fe3+ DTPA and 10 or 20 mM NaHCO3. These physiological responses were scored at 1, 3, 7, and 28 days from the start of the in vitro assay. Leaf total chlorophyll content, the capacity of roots to acidify the medium, reduced iron, and exudates of phenolic acids and organic acids were analyzed in each media and time sample. Leaf chlorophyll levels for the clones derived from Pcc were the highest, especially under the highest bicarbonate concentration, followed by those derived from Pap and Pa. The higher chlorophyll content of Pcc clones were related with their higher capacity to acidify the media but not with their iron reduction capacity at the root level. On the other hand, hybrid clones derived from Pe showed a higher Fe3+ reduction ability than clones from all the other species during the whole assay but only when the bicarbonate concentration was lower. The exudation of phenolic acids by the roots was higher in Pcw than in the other species, and this response might explain why the total chlorophyll levels in Pcw clones are similar to those of Pe and Pa ones. These results with Pyrus spp. bring more evidence in support of the idea that iron reduction capacity at the root level is not directly related with a higher tolerance to iron deficiency caused by the high pH of calcareous soils. Instead, the ability to acidify the rhizosphere is the trait of choice for the selection of the pear hybrid clones better adapted to lime induced chlorosis. In addition, the in vitro assay to select the Pyrus clones for tolerance to iron chlorosis could be shortened to one week of culture in 10 mM NaHCO3, measuring the leaf chlorophyll level, acidification of the culture medium, and exudation of phenolic acids as the physiological responses to predict tolerance to lime-induced chlorosis.
39
Bhatt, Pankaj, Amit Verma, Shulbhi Verma, Md Shahbaz Anwar, Parteek Prasher, Harish Mudila e Shaohua Chen. "Understanding Phytomicrobiome: A Potential Reservoir for Better Crop Management". Sustainability 12, n. 13 (6 luglio 2020): 5446. http://dx.doi.org/10.3390/su12135446.
Abstract (sommario):
Recent crop production studies have aimed at an increase in the biotic and abiotic tolerance of plant communities, along with increased nutrient availability and crop yields. This can be achieved in various ways, but one of the emerging approaches is to understand the phytomicrobiome structure and associated chemical communications. The phytomicrobiome was characterized with the advent of high-throughput techniques. Its composition and chemical signaling phenomena have been revealed, leading the way for “rhizosphere engineering”. In addition to the above, phytomicrobiome studies have paved the way to best tackling soil contamination with various anthropogenic activities. Agricultural lands have been found to be unbalanced for crop production. Due to the intense application of agricultural chemicals such as herbicides, fungicides, insecticides, fertilizers, etc., which can only be rejuvenated efficiently through detailed studies on the phytomicrobiome component, the phytomicrobiome has recently emerged as a primary plant trait that affects crop production. The phytomicrobiome also acts as an essential modifying factor in plant root exudation and vice versa, resulting in better plant health and crop yield both in terms of quantity and quality. Not only supporting better plant growth, phytomicrobiome members are involved in the degradation of toxic materials, alleviating the stress conditions that adversely affect plant development. Thus, the present review compiles the progress in understanding phytomicrobiome relationships and their application in achieving the goal of sustainable agriculture.
40
Pickard, William F. "The riddle of root pressure. II. Root exudation at extreme osmolalities". Functional Plant Biology 30, n. 2 (2003): 135. http://dx.doi.org/10.1071/fp02036.
Abstract (sommario):
To test the predictions of a recent theory of root pressure and exudation, exudation from detopped tomato seedlings was studied. Experimental findings were generally in qualitative accord with the theory. Two confirmed predictions are of particular interest. First, when a normally exuding stump was challenged by having its roots exposed to concentrated osmolyte, the exudation rate dropped quickly to zero but later often recovered to a higher level. Second, when exudation from a plant challenged by concentrated osmolyte did not recover, flushing the soil solution away with tap water usually resulted in a sudden resumption of exudation followed by a rapid falloff.
41
Korenblum, Elisa, Yonghui Dong, Jedrzej Szymanski, Sayantan Panda, Adam Jozwiak, Hassan Massalha, Sagit Meir, Ilana Rogachev e Asaph Aharoni. "Rhizosphere microbiome mediates systemic root metabolite exudation by root-to-root signaling". Proceedings of the National Academy of Sciences 117, n. 7 (3 febbraio 2020): 3874–83. http://dx.doi.org/10.1073/pnas.1912130117.
Abstract (sommario):
Microbial communities associated with roots confer specific functions to their hosts, thereby modulating plant growth, health, and productivity. Yet, seminal questions remain largely unaddressed including whether and how the rhizosphere microbiome modulates root metabolism and exudation and, consequently, how plants fine tune this complex belowground web of interactions. Here we show that, through a process termed systemically induced root exudation of metabolites (SIREM), different microbial communities induce specific systemic changes in tomato root exudation. For instance, systemic exudation of acylsugars secondary metabolites is triggered by local colonization of bacteria affiliated with the genus Bacillus. Moreover, both leaf and systemic root metabolomes and transcriptomes change according to the rhizosphere microbial community structure. Analysis of the systemic root metabolome points to glycosylated azelaic acid as a potential microbiome-induced signaling molecule that is subsequently exuded as free azelaic acid. Our results demonstrate that rhizosphere microbiome assembly drives the SIREM process at the molecular and chemical levels. It highlights a thus-far unexplored long-distance signaling phenomenon that may regulate soil conditioning.
42
Volkov, Vadim, e Heiner Schwenke. "A Quest for Mechanisms of Plant Root Exudation Brings New Results and Models, 300 Years after Hales". Plants 10, n. 1 (25 dicembre 2020): 38. http://dx.doi.org/10.3390/plants10010038.
Abstract (sommario):
The review summarizes some of our current knowledge on the phenomenon of exudation from the cut surface of detached roots with emphasis on results that were mostly established over the last fifty years. The phenomenon is quantitatively documented in the 18th century (by Hales in 1727). By the 19th century, theories mainly ascribed exudation to the secretion of living root cells. The 20th century favored the osmometer model of root exudation. Nevertheless, growing insights into the mechanisms of water transport and new or rediscovered observations stimulated the quest for a more adequate exudation model. The historical overview shows how understanding of exudation changed with time following experimental opportunities and novel ideas from different areas of knowledge. Later theories included cytoskeleton-dependent micro-pulsations of turgor in root cells to explain the observed water exudation. Recent progress in experimental biomedicine led to detailed study of channels and transporters for ion transport via cellular membranes and to the discovery of aquaporins. These universal molecular entities have been incorporated to the more complex models of water transport via plant roots. A new set of ideas and explanations was based on cellular osmoregulation by mechanosensitive ion channels. Thermodynamic calculations predicted the possibility of water transport against osmotic forces based on co-transport of water with ions via cation-chloride cotransporters. Recent observations of rhizodermis exudation, exudation of roots without an external aqueous medium, segments cut from roots, pulses of exudation, a phase shifting of water uptake and exudation, and of effects of physiologically active compounds (like ion channel blockers, metabolic agents, and cytoskeletal agents) will likely refine our understanding of the phenomenon. So far, it seems that more than one mechanism is responsible for root pressure and root exudation, processes which are important for refilling of embolized xylem vessels. However, recent advances in ion and water transport research at the molecular level suggest potential future directions to understanding of root exudation and new models awaiting experimental testing.
43
Ohta, Tamihisa, e Tsutom Hiura. "Root exudation of low-molecular-mass-organic acids by six tree species alters the dynamics of calcium and magnesium in soil". Canadian Journal of Soil Science 96, n. 2 (1 giugno 2016): 199–206. http://dx.doi.org/10.1139/cjss-2015-0063.
Abstract (sommario):
Soils in plantations of Cryptomeria japonica in Japan have ∼threefold more exchangeable Ca compared with soils in other types of forest vegetation even in a Ca-poor environment. To explain mechanisms underlying this phenomenon, we determined the effect of root exudation rate of low-molecular-mass organic acids (LMMOAs) on exchangeable cations in soil. We conducted a pot experiment using C. japonica and five dominant tree species in Japan, and measured the root exudation rates of LMMOAs and exchangeable nutrient concentrations in the soils. To estimate whether the root exudation rate of LMMOAs is elevated in response to Ca deficiency, we created variation in Ca availability by adding different amounts of crushed oyster shells. The root exudation rates of LMMOAs were two to five times higher for C. japonica than for other tree species, but did not differ significantly among the different quantities of oyster shell. Exchangeable Ca and Mg were significantly higher in the soils with C. japonica and significantly correlated with the root exudation rate of LMMOAs (R2 > 0.24) at high and moderate quantities of oyster shell. Therefore, variation among species, in terms of root exudation of organic acids, might be one important factor affecting the cation dynamics in soil.
44
Zhang, Chengfu, Qingxia Zhao, Yinmei Cai, Tao Zhang, Limin Zhang e Tengbing He. "Effect of Litter Removal and Addition on Root Exudation and Associated Microbial N Transformation in a Pinus massoniana Plantation". Forests 14, n. 7 (25 giugno 2023): 1305. http://dx.doi.org/10.3390/f14071305.
Abstract (sommario):
In forest ecosystems, variations in aboveground litter input caused by global changes, substantially alter soil N cycling. In field-grown plants, few studies have directly measured root exudation rates and quantified their effects on N transformations under litter manipulation. We quantified soil N transformation rate responses to litter manipulation in a Pinus massoniana plantation, and unravelled the effect of root exudation on soil N transformations. We measured in situ P. massoniana root exudation rates as well as soil microbial biomass, soil C and N concentrations, the activities of four soil enzymes involved in soil N transformations, and net N mineralization and net nitrification rates after experimental litter removal and litter addition treatments. Litter removal and litter addition treatments had little impact on soil C and N concentrations, microbial biomass, soil enzyme (urease, hydroxylamine reductase, nitrate reductase, and nitrite reductase) activity, and net N mineralization rates. However, both litter removal and addition increased net N nitrification rates. Additionally, litter removal significantly decreased root C exudation rates (in April 2021 and annually), whereas litter addition had no significant effects on root C exudation rates across all seasons. Furthermore, root C exudation rates were positively associated with urease and nitrate reductase activities, but negatively associated with hydroxylamine reductase and nitrite reductase activities, as well as net N nitrification rate. Overall, we demonstrated that root exudates may be an important physiological adjustment by which trees respond to changes in litter input caused by global environmental changes, regulating underground N biochemical processes. Furthermore, we provide new evidence from root exudates for understanding the potential influence of litter inputs on soil N cycling. A strong correlation exists between root exudates and N transformation, shedding new light on the dynamics of rhizosphere nutrient cycling crucial for maintaining forest ecosystem stability and productivity under changing environmental conditions.
45
Proctor, Cameron, e Yuhong He. "Modeling Root Exudate Accumulation Gradients to Estimate Net Exudation Rates by Peatland Soil Depth". Plants 10, n. 1 (6 gennaio 2021): 106. http://dx.doi.org/10.3390/plants10010106.
Abstract (sommario):
Root exudates accumulate as a radial gradient around the root, yet little is known about variability at the individual root level. Vertical gradients in soil properties are hypothesized to cause greater accumulation of exudates in deeper soil through hindering diffusion, increasing sorption, and decreasing mineralization. To this end, a single root exudation model coupling concentration specific exudation and depth dependent soil properties was developed. The model was parameterized for a peatland ecosystem to explore deposition to the methanogen community. Numerical experiments indicate that exudates accumulated to a greater extent in deeper soil, albeit the effect was solute specific. Rhizosphere size for glucose doubled between the 10 and 80 cm depths, while the rhizoplane concentration was 1.23 times higher. Root influx of glucose increased from 1.431 to 1.758 nmol cm−1 hr−1, representing a recapture efficiency gain of 15.74% (i.e., 69.06% versus 84.8%). Driven by increased root influx, overall net exudation rates of select sugars and amino acids varied by a factor two. Model sensitivity analysis revealed that soil depth and root influx capability are key determinants of the rhizoplane concentration and subsequently net exudation, which determines whether effluxed compounds escape the root oxic shell and are available to the methanogen community.
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Dixon, R. K., H. E. Garrett e G. S. Cox. "Carbohydrate Relationships of Citrus jambhiri Inoculated with Glomus fasciculatum". Journal of the American Society for Horticultural Science 113, n. 2 (marzo 1988): 239–42. http://dx.doi.org/10.21273/jashs.113.2.239.
Abstract (sommario):
Abstract Root exudation patterns and carbohydrate composition of roots and leaves of Citrus jambhiri Lush, were examined during the period of initial colonization by Glomus fasciculatum (Thaxt.) Gerd. and Trappe. Exudation of reducing sugars and amino acids from seedling roots decreased as soil and root P increased. Comparison of vesicular-arbuscular mycorrhizal (VAM) seedlings to nonmycorrhizal seedlings of similar size and P nutrition revealed root exudation in VAM plants decreased following fungal colonization. Root reducing sugars increased and root starch content decreased in VAM seedlings during the infection process. Following establishment of symbiosis, leaves of VAM seedlings had greater levels of total soluble sugar, sucrose, reducing sugars, and starch relative to nonmycorrhizal controls. Colonization of C. jambhiri roots by VAM fungi apparently alters the balance of carbohydrates within leaves and roots.
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Siane, Bless Aplena Elen. "Citrate Root Exudation under Zn and P Deficiency". JOURNAL OF TROPICAL SOILS 17, n. 3 (25 gennaio 2013): 219. http://dx.doi.org/10.5400/jts.2012.v17i3.219-225.
Abstract (sommario):
Zinc and phosphorus are essential nutrients with low bioavailability in calcareous soils. Some plants exude organicacids to increase the solubility of these two nutrients. The objective of this study was to examine citrate exudation rates of different lupin (Feodora and Energy) and rapeseed (Dunkeld, Yickadee and Rainbow) cultivars under deficiencies of Zn and P. The plants were cultivated into three different nutrient solutions (complete, -Zn, and -P) with pH around 7. Under Zn deficiency, rapeseed cultivars lost about 80% of its shoot fresh weight, but the roots did not exude any organic acids such as citrate, malate or oxalate. Both lupin and rapeseed cultivars exuded citrate onlyunder phosphorus deficiency. The exudation rates of Feodora and Energy were 3.89 μmol g-1 RDW h-1 and 3.45 μmol g-1 RDW h-1, respectively, while that of Dunkeld was 15.1 μmol g-1 RDW h-1. The results indicated that lupin and rapeseed lost their production under Zn deficiency but they did not exude organic acid, while under P deficiency both plants exuded citrate.Keywords: Citrate; deficiency; exudation rate; lupin; phosphorus; rapeseed; Zn[How to Cite: Siane BAE. 2012. Citrate Root Exudation under Zn and P Deficiency. J Trop Soils, 17 (3) : 219-225. doi: 10.5400/jts.2012.17.3.219][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.3.219]
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Fritz, Michael, Stephan Lorenzen, Maria Popova e Rudolf Ehwald. "Transient and permanent changes of xylem sap exudation by root systems of Zea mays after application of hydrostatic and osmotic forces". Functional Plant Biology 37, n. 9 (2010): 813. http://dx.doi.org/10.1071/fp10053.
Abstract (sommario):
Effects of relatively small changes of hydrostatic and osmotic pressure on root exudation were studied with maize (Zea mays L.) plants grown in hydroculture to estimate the root reflection coefficient for the applied osmolyte (PEG 600). During the first seconds after a change in hydrostatic pressure, the exudation rate measured with a microflow sensor was instantaneously and strongly changed due to elastic deformation of the metaxylem vessels in the branched part of the main root axis. In osmotic experiments, a time of 10–20 s was required before the maximum change of the exudation rate was recorded. This retardation can be explained by diffusive saturation of the non-agitated root surface film and radial turgor propagation. A new standing osmotic gradient was reached within 4 min after a change of the water potential difference (osmotic, hydrostatic). The steady-state exudation rate J was altered by osmotic and hydrostatic forces with nearly equal efficiencies when branch roots were not injured. Hence, the reflection coefficient of the intact root for PEG 600 was close to unity. The results are in accord with nearly ideal reverse osmosis at high rates of water uptake by roots and confirm the absence of a significant hydraulic bypath circumventing the protoplasts.
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Chetverikov, Sergey, Lidiya Vysotskaya, Elena Kuzina, Tatiana Arkhipova, Margarita Bakaeva, Gulnaz Rafikova, Tatiana Korshunova, Darya Chetverikova, Gaisar Hkudaygulov e Guzel Kudoyarova. "Effects of Association of Barley Plants with Hydrocarbon-Degrading Bacteria on the Content of Soluble Organic Compounds in Clean and Oil-Contaminated Sand". Plants 10, n. 5 (13 maggio 2021): 975. http://dx.doi.org/10.3390/plants10050975.
Abstract (sommario):
Plant-bacteria consortia are more effective in bioremediation of petroleum contaminated soil than when either organism is used individually. The reason for this is that plant root exudates promote growth and activity of oil degrading bacteria. However, insufficient attention has been paid to the ability of bacteria to influence root exudation. Therefore, the influence of barley plants and/or bacterial inoculation (Pseudomonas hunanensis IB C7 and Enterobacter sp. UOM 3) on the content of organic acids, sugars and plant hormones in the eluate from clean and oil-polluted sand was studied separately or in combination. These strains are capable of oxidizing hydrocarbons and synthesizing auxins. Concentrations of organic acids and sugars were determined using capillary electrophoresis, and hormones by enzyme-linked immunosorbent assays. In the absence of plants, no sugars were detected in the sand, confirming that root exudates are their main source. Introducing bacteria into the sand increased total contents of organic compounds both in the presence and absence of oil. This increase could be related to the increase in auxin amounts in the sand eluate, as well as in plants. The results indicate that bacteria are able to increase the level of root exudation. Since auxins can promote root exudation, bacterial production of this hormone is likely responsible for increased concentrations of soluble organic compounds in the sand. Bacterial mediation of root exudation by affecting plant hormonal status should be considered when choosing microorganisms for phytoremediation.
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Walker, Travis S., Harsh Pal Bais, Erich Grotewold e Jorge M. Vivanco. "Root Exudation and Rhizosphere Biology: Fig. 1." Plant Physiology 132, n. 1 (1 maggio 2003): 44–51. http://dx.doi.org/10.1104/pp.102.019661.