Academic literature on the topic 'Angiosperms'
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Journal articles on the topic "Angiosperms"
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Wang, Xin. "A Novel Early Cretaceous Flower and Its Implications on Flower Derivation." Biology 11, no. 7 (July 11, 2022): 1036. http://dx.doi.org/10.3390/biology11071036.
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Background: The origin and early evolution of angiosperms, by far the most important plant group for human beings, are questions demanding answers, mainly due to a lack of related fossils. The Yixian Formation (Lower Cretaceous) is famous for its fossils of early angiosperms, and several Early Cretaceous angiosperms with apocarpous gynoecia have been documented. However, a hypanthium and an inferior ovary are lacking in these fossil angiosperms. Methods: The specimen was collected from the outcrop of the Yixian Formation in Dawangzhangzi in the suburb of Lingyuan, Liaoning, China. The specimen was photographed using a Nikon D200 digital camera, and its details were photographed using a Nikon SMZ1500 stereomicroscope and a MAIA3 TESCAN SEM. Results: A fossil angiosperm, Lingyuananthus inexpectus gen. et sp. nov, is reported from the Lower Cretaceous of China. Differing from those documented previously, Lingyuananthus has a hypanthium, an inferior ovary, and ovules inside its ovary. Such a character assemblage indicates its angiospermous affinity, although not expected by any existing leading angiosperm evolutionary theory. Conclusions: New fossil material with a unique character assemblage falls beyond the expectation of the currently widely accepted theories of angiosperm evolution. Together with independently documented fossils of early angiosperms, Lingyuananthus suggests that at least some early angiosperms’ flowers can be derived in a way that has been ignored previously.
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Friis, Else Marie, Peter R. Crane, Kaj Raunsgaard Pedersen, Mário Miguel Mendes, and Jiří Kvaček. "The Early Cretaceous mesofossil flora of Catefica, Portugal: angiosperms." Fossil Imprint 78, no. 2 (2022): 341–424. http://dx.doi.org/10.37520/fi.2022.016.
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Angiosperm mesofossils are described from the Lower Cretaceous Almargem Formation exposed near the village of Catefica, Portugal, and are thought to be of Aptian-early Albian age. The mesofossil assemblage from Catefica is diverse and, in addition to the angiosperms described here, also contains a rich assemblage of non-angiosperm fossils, including leafy axes of bryophytes and lycopsids, lycopsid and salvinialean megaspores, and sporangia, sori and leaf fragments of ferns. There are also twigs, cones, cone scales, seeds and sporangia of several kinds of conifers. Other seed plants include 11 species of chlamydospermous seeds and vegetative axes related to the BEG group (Bennettiales-Erdtmanithecales-Gnetales). In terms of the number of plant fragments identified, angiosperms are most abundant in the Catefica assemblage and account for more than half of all specimens. Angiosperms also dominate in number of species, but because the non-angiosperm fossils have not been studied in detail the total number of species in the flora is not yet established. Sixty-seven species of angiosperms are recognized. Angiosperm diversity is mainly at the level of non-eudicots, including ANA-grade angiosperms, Chloranthaceae and magnoliids. Remains of chloranthoid angiosperms are especially common, both in the number of specimens and in number of species recognized. About 40 % of the specimens, and more than 25 % of the species are chloranthoids. Remains of magnoliid angiosperms (Magnoliales, Laurales, Canellales, Piperales) are also prominent among the angiosperms. Eudicots are subordinate: only 3–4 % of all angiosperm specimens can be assigned confidently to eudicot angiosperms. Five new genera and six new species of angiosperms are established (Canrightia foveolata sp. nov., Elasmostemon paisii gen. et sp. nov., Endressistemon cateficensis gen. et sp. nov., Ibericarpus cuneiformis gen. et sp. nov., Proencistemon portugallicus gen. et sp. nov., Valvidistemon globiferus gen. et sp. nov.). Several other new taxa are also described, but not formally named.
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Feild, Taylor S., Garland R. Upchurch, David S. Chatelet, Timothy J. Brodribb, Kunsiri C. Grubbs, Marie-Stéphanie Samain, and Stefan Wanke. "Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves." Paleobiology 37, no. 2 (2011): 195–213. http://dx.doi.org/10.1666/10015.1.
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The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.
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Doyle, James A. "Significance of molecular phylogenetic analyses for paleobotanical investigations on the origin of angiosperms." Journal of Palaeosciences 50, no. (1-3) (December 31, 2001): 167–88. http://dx.doi.org/10.54991/jop.2001.1821.
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Molecular phylogenetic analyses have provided increasing evidence that angiosperms are not related to Gnetales, thus contradicting the anthophyte hypothesis based on morphological cladistic analyses and throwing the question of angiosperm relatives back to paleobotanists. Previous analyses of gene sequences based on a molecular clock conflicted with the fossil record in indicating a Late Palaeozoic or Triassic origin of the angiosperms, but closer examination suggests that these dates were biased by the use of herbaceous taxa with accelerated rates of molecular evolution. Despite uncertainty on angiosperm relatives, analyses of many genes consistently place Amborella, Nymphaeales, Austrobaileya, Trimenia and Illiciales (the ‘ANITA grade') at the base of extant angiosperms, possibly followed by Chloranthaceae. Molecular phylogenies imply that the first crown-group angiosperms had columellar exine structure, suggesting that Hauterivian-Barremian reticulate-columellar monosulcates may be closer to the origin of angiosperms than was thought when granular Magnoliales were believed to be basal. Hauterivian pollen with a verrucate tectum and microspinules is especially similar to Amborella. The ANITA lines and Chloranthaceae have ascidiate carpels sealed by secretion and often exotestal seeds, fitting the abundance of such carpels and seeds in Barremian-Aptian mesofloras. Similarities between Aptian angiosperm leaves and ANITA taxa, such as chloranthoid teeth and variable stomatal structure, also suggest that Early Cretaceous angiosperms were more primitive than previously appreciated. Molecular results may help refine search images for extinct angiosperm relatives, away from Gnetales and toward groups such as Caytonia, Glossopterids, Bennettitales and Corystosperms. Since molecular data place the vesselless taxa Amborella and Nymphaeales at the base of the angiosperms, the presence of vessels is not evidence that gigantopterids are related to angiosperms. The conclusion that columellar structure is ancestral reaffirms the potential of Triassic reticulate-columellar Crinopolles pollen as angiosperm relatives.
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Sun Ge and D. L. Dilcher. "Early angiosperms from Lower Cretaceous of Jixi, China and their significance for study of the earliest occurrence of angiosperms in the world." Journal of Palaeosciences 45 (December 31, 1996): 393–99. http://dx.doi.org/10.54991/jop.1996.1260.
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This paper reports the recent study of the earliest known angiosperms in the world found from the Lowe Cretaceous of Jixi, China, and first demonstrates the general information on the oldest known Inflorescences Xingxueina heilongfiangensis Sun et Dilcher (MS) contained in the Jixi early angiosperms. The inflorescences possess numerous pollens in situ, very small, inaperturate and tectate-columellate in exine, and can be compared to those from Valanginian-Hauterivian of Israel studied by Brenner (1995). Based on the comparison and on the marine beds, yielding Valanginian-Hauterivian dinoflagellates, underlying conformably the angiosperm-bearing beds the Jixi angiosperms are considered Hauterivian or Hauterivian-Early Barremian in age. The paper has also discussed the findings of the angiosperm-like or questionable angiosperm material newly from China and previously from Mongolia, proposed there might exist an original centre of angiosperms in East Asia. However, it would not be excluded that there were two original centres (East Asia and Eastern Gondwanaland) where the earliest angiosperms evolved and developed in parallel during the early time of Early Cretaceous.
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Lee, Alexandra P., Garland Upchurch, Erik H. Murchie, and Barry H. Lomax. "Leaf energy balance modelling as a tool to infer habitat preference in the early angiosperms." Proceedings of the Royal Society B: Biological Sciences 282, no. 1803 (March 22, 2015): 20143052. http://dx.doi.org/10.1098/rspb.2014.3052.
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Despite more than a century of research, some key aspects of habitat preference and ecology of the earliest angiosperms remain poorly constrained. Proposed growth ecology has varied from opportunistic weedy species growing in full sun to slow-growing species limited to the shaded understorey of gymnosperm forests. Evidence suggests that the earliest angiosperms possessed low transpiration rates: gas exchange rates for extant basal angiosperms are low, as are the reconstructed gas exchange rates for the oldest known angiosperm leaf fossils. Leaves with low transpirational capacity are vulnerable to overheating in full sun, favouring the hypothesis that early angiosperms were limited to the shaded understorey. Here, modelled leaf temperatures are used to examine the thermal tolerance of some of the earliest angiosperms. Our results indicate that small leaf size could have mitigated the low transpirational cooling capacity of many early angiosperms, enabling many species to survive in full sun. We propose that during the earliest phases of the angiosperm leaf record, angiosperms may not have been limited to the understorey, and that some species were able to compete with ferns and gymnosperms in both shaded and sunny habitats, especially in the absence of competition from more rapidly growing and transpiring advanced lineages of angiosperms.
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Friis, Else Marie, Kaj Raunsgaard Pedersen, and Peter R. Crane. "Diversity in obscurity: fossil flowers and the early history of angiosperms." Philosophical Transactions of the Royal Society B: Biological Sciences 365, no. 1539 (February 12, 2010): 369–82. http://dx.doi.org/10.1098/rstb.2009.0227.
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In the second half of the nineteenth century, pioneering discoveries of rich assemblages of fossil plants from the Cretaceous resulted in considerable interest in the first appearance of angiosperms in the geological record. Darwin's famous comment, which labelled the ‘rapid development’ of angiosperms an ‘abominable mystery’, dates from this time. Darwin and his contemporaries were puzzled by the relatively late, seemingly sudden and geographically widespread appearance of modern-looking angiosperms in Late Cretaceous floras. Today, the early diversification of angiosperms seems much less ‘rapid’. Angiosperms were clearly present in the Early Cretaceous, 20–30 Myr before they attained the level of ecological dominance reflected in some mid-Cretaceous floras, and angiosperm leaves and pollen show a distinct pattern of steadily increasing diversity and complexity through this interval. Early angiosperm fossil flowers show a similar orderly diversification and also provide detailed insights into the changing reproductive biology and phylogenetic diversity of angiosperms from the Early Cretaceous. In addition, newly discovered fossil flowers indicate considerable, previously unrecognized, cryptic diversity among the earliest angiosperms known from the fossil record. Lineages that today have an herbaceous or shrubby habit were well represented. Monocotyledons, which have previously been difficult to recognize among assemblages of early fossil angiosperms, were also diverse and prominent in many Early Cretaceous ecosystems.
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Bateman, Richard M. "Hunting the Snark: the flawed search for mythical Jurassic angiosperms." Journal of Experimental Botany 71, no. 1 (September 20, 2019): 22–35. http://dx.doi.org/10.1093/jxb/erz411.
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Abstract Several recent palaeobotanical studies claim to have found and described pre-Cretaceous angiosperm macrofossils. With rare exceptions, these papers fail to define a flower, do not acknowledge that fossils require character-based rather than group-based classification, do not explicitly state which morphological features would unambiguously identify a fossil as angiospermous, ignore the modern conceptual framework of phylogeny reconstruction, and infer features in the fossils in question that are interpreted differently by (or even invisible to) other researchers. This unfortunate situation is compounded by the relevant fossils being highly disarticulated two-dimensional compression-impressions lacking anatomical preservation. Given current evidence, all supposed pre-Cretaceous angiosperms are assignable to other major clades among the gymnosperms sensu lato. By any workable morphological definition, flowers are not confined to, and therefore cannot delimit, the angiosperm clade. More precisely defined character states that are potentially diagnostic of angiosperms must by definition originate on the phylogenetic branch that immediately precedes the angiosperm crown group. Although the most reliable candidates for diagnostic characters (triploid endosperm reflecting double fertilization, closed carpel, bitegmic ovule, and phloem companion cells) are rarely preserved and/or difficult to detect unambiguously, similar characters have occasionally been preserved in high-quality permineralized non-angiosperm fossils. The angiosperm radiation documented by Early Cretaceous fossils involves only lineages closely similar to extant taxonomic families, lacks obvious morphological gaps, and (as agreed by both the fossil record and molecular phylogenies) was relatively rapid—all features that suggest a primary radiation. It is unlikely that ancestors of the crown group common ancestor would have fulfilled a character-based definition of (and thereby required expansion of the concept of) an angiosperm; they would instead form a new element of the non-angiosperm members of the ‘anthophyte’ grade, competing with Caytonia to be viewed as morphologically determined sister group for angiosperms. Conclusions drawn from molecular phylogenetics should not be allowed to routinely constrain palaeobotanical inferences; reciprocal illumination between different categories of data offers greater explanatory power than immediately resorting to Grand Syntheses. The Jurassic angiosperm—essentially a product of molecular phylogenetics—may have become the holy grail of palaeobotany but it appears equally mythical.
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Lusk, Christopher H., Mylthon Jiménez-Castillo, and Nicolás Salazar-Ortega. "Evidence that branches of evergreen angiosperm and coniferous trees differ in hydraulic conductance but not in Huber values." Canadian Journal of Botany 85, no. 2 (January 2007): 141–47. http://dx.doi.org/10.1139/b07-002.
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The hydraulic efficiency conferred by vessels is regarded as one of the key innovations explaining the historical rise of the angiosperms at the expense of the gymnosperms. Few studies, however, have compared the structure and function of xylem and their relationships with foliage traits in evergreen representatives of both groups. We measured sapwood cross-sectional area, conduit diameters, hydraulic conductance, and leaf area of fine branches (2.5–7.5 mm diameter) of five conifers and eight evergreen angiosperm trees in evergreen temperate forests in south-central Chile. Conductance of both lineages was higher at Los Lleuques, a warm temperate site with strong Mediterranean influence, than in a cool temperate rain forest at Puyehue. At a common sapwood cross-sectional area, angiosperm branches at both sites had greater hydraulic conductance (G) than conifers, but similar leaf areas. Branch conductance normalized by subtended leaf area (GL) at both sites was, therefore, higher in angiosperms than in conifers. Hydraulically weighted mean conduit diameters were much larger in angiosperms than in conifers, although this difference was less marked at Puyehue, the cooler of the two sites. Conduits of the vesselless rain forest angiosperm Drimys winteri J.R. & G. Forst were wider than those of coniferous associates, although narrower than angiosperm vessels. However, GL of D. winteri was within the range of values measured for vesselbearing angiosperms at the same site. The observed differences in xylem structure and function correlate with evidence that evergreen angiosperms have higher average stomatal conductance and photosynthetic capacity than their coniferous associates in southern temperate forests. Comparisons of conifers and angiosperm branches thus suggest that the superior capacity of angiosperm conduits is attributable to the development of higher gas-exchange rates per unit leaf area, rather than to a more extensive leaf area. Results also suggest that the tracheary elements of some vesselless angiosperms differ in width and hydraulic efficiency from conifer tracheids.
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Jawaray, Wilfridus Balla, Erfy Melany Lalupan, Anita Tamu Ina, and Agus Kusumanegara. "KEANEKARAGAMAN TUMBUHAN ANGIOSPERMAE DI KAWASAN TAMAN NASIONAL MATALAWA KABUPATEN SUMBA TIMUR." Jurnal Biosilampari : Jurnal Biologi 5, no. 2 (June 1, 2023): 169–77. http://dx.doi.org/10.31540/biosilampari.v5i2.1708.
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The highest plant diversity in the tropical rainforest area in Matalawa National Park is the Angiospermae plant. There are still many people in Praingkareha Village who are not familiar with Angiospermae plants or closed seed plants. This study aims to describe the diversity index of Angiosperm plants found in the Laputi Forest block, Matalawa National Park. This research was limited to the Laputi Forest block, so it did not cover the entire forest in Praingkareha Village, Matalawa National Park, East Sumba Regency. This study used a double plot method with a purposive sampling technique. The results showed that there were 30 species of Angiosperms from 17 families with a total of 499 individuals. The diversity of Angiosperm plants in the Laputi Forest block of the Matalawa National Park area is moderate with (Ĥ)=2.90.
Dissertations / Theses on the topic "Angiosperms"
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Marlowe, Karol. "Biogeography and evolution of flowering plants in the American West : Gaillardia (asteraceae) and Synthyris (plantaginaceae)." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Spring2007/k_marlowe_043007.pdf.
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Yu, Boying. "Gametogenesis and flower development controlled by AtAnamorsin1 and AtPUB4." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/158.
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Flowers are the organs for sexual reproduction in angiosperms. Gametogenesis in floral organs leads to formation of sperms and eggs and their fertilization forms a zygote that develops into a new plant. Gametogenesis and embryogenesis involve precisely regulated biological processes controlled by complex networks of genes and pathways. In this study, AtANA1, which was identified as a redox sensitive protein in previous study, was found to be essential for embryogenesis and also plays an important role in both male and female gametogenesis. Without a functional AtANA1, embryo development is arrested after the first cell division of the zygote. The ana1 mutation also causes arrest in different steps of male and female gametogenesis. Aborting pollen and embryos caused by the ana1 mutation exhibit enhanced accumulation of reactive oxygen species and DNA fragmentation, marks of programmed cell death. Presence of aborting ana1 pollen was also found to lead to abortion of wild type pollen in the same anther, raising a possibility that the aborting ana1 pollen might release a death signal. ANA1 could be involved in an oxidative stress signaling pathway, and loss of its function triggers death of gametophytic and embryonic cells. Another important protein involved in Arabidopsis reproductive processes is PUB4, an E3 ubiquitin ligase. The pub4 mutation was previously found to cause abnormal enlargement of tapetal cells and incomplete degeneration of the tapetum layer, resulting in a defect in pollen release and conditional male sterility. In this study, we characterized PUB4’s role in controlling floral meristem determinacy. The pub4 mutation causes formation of ectopic floral organs inside of carpels/siliques. It was found that the pub4 mutation leads to ectopic expression of WUSCHEL, an important regulator which is essential for maintaining shoot apical meristem and floral meristem, which could be responsible for the flower-in-flower phenotype. PUB4 appears to work additively with AGAMOUS (AG) to control appropriate expression of the WUS gene. Three extra large G proteins (XLGs) in Arabidopsis, which interact with PUB4, also play roles in controlling tapetal cell enlargement and degeneration. However, XLGs might not function in floral meristem determinacy.
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Lee, Alexandra P. "CO2 decline and the rise of the angiosperms." Thesis, University of Nottingham, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716841.
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The angiosperms (flowering plants) occupy almost every habitat type on Earth and comprise nearly 90% of extant plant species. Yet this dominance is a relatively recent (geological) occurrence as they have a late evolutionary origin (-140 Ma). The Cretaceous angiosperm radiation to dominance temporally coincides with a time of atmospheric CO2 ([CO2]) decline and detrimentally impacted pteridophyte and cycad diversity in the understorey and gymnosperm diversity in the canopy. The first objective of this thesis was to investigate [CO2] decline as a trigger for the rise of the angiosperms. Six species were grown at modern ambient and three elevated levels of [CO2] (800, 1200 and 2000 ppm), which corresponded to Cretaceous concentrations. The comparative ability of these species to acclimate physiologically, morphologically and biochemically were used as a model for Cretaceous plant groups. Ranunculus acrls and Polypodium vulgare, were chosen to represent Cretaceous understorey angiosperms and pteridophytes respectively. Liquidambar styraciflua and Laurus nobills represented canopy angiosperms and Ginkgo biloba and Metasequoia glyptostroboides canopy gymnosperms.
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Reyes, Elisabeth. "Evolutionary history of floral key innovations in angiosperms." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS489/document.
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Les Angiospermes forment un clade connu pour sa grande diversité d’espèces et une répartition inégale de cette diversité en son sein. Ce travail se concentre sur la reconstruction d’états ancestraux de caractères floraux sur les phylogénies dans le but d’étudier leur impact sur la diversification. En premier lieu, nous nous sommes focalisés sur deux innovations-clés potentielles chez les Proteaceae, la symétrie bilatérale du périanthe et la présence dans les hotspots à climat méditerranéen. L’utilisation sur une phylogénie de modèles de diversification dépendants des états de caractère a permis de montrer que le premier état caractère n’a pas d’impact significatif sur la diversification des espèces dans ce groupe, contrairement au second. Ensuite, nous avons reconstruit les états ancestraux de la symétrie du périanthe à l’échelle de toutes les Angiospermes, avec une stratégie d’échantillonnage permettant de refléter toutes les transitions de ce caractère. Nous avons mis en évidence un minimum de 130 origines de la symétrie bilatérale, suivies de 69 réversions vers la symétrie radiaire. Enfin, la même méthode a été étendue à l’étude de quatre autres caractères du périanthe. Différents modèles de reconstruction d’états ancestraux ont été utilisés sur une phylogénie de 1232 espèces pour examiner l’influence des changements de modèle sur les états ancestraux reconstruits. Nos résultats montrent que les changements de modèles de reconstruction ont une influence sur l’état de certains nœuds seulement, jamais sur l’ensemble. Les différents résultats trouvés pour la symétrie, caractère commun aux trois chapitres, révèlent que notre méthode d’échantillonnage présente l’inconvénient d’estimer des taux de transition trop élevés pour donner des résultats concluants avec la méthode du maximum de vraisemblance. Les résultats sont en revanche beaucoup moins biaisés lorsque l’on examine plusieurs caractères simultanémentAngiosperms are a clade known for its great species diversity and the uneven distribution of this diversity among its lineages. This work focuses on the ancestral state reconstruction of floral characters on phylogenies in the purpose of studying their impact on diversification. We first focused on two potential key innovations in Proteaceae, bilateral perianth symmetry and presence in Mediterranean-climate hotspots. Using character state dependent diversification models, we found that the first character state did not have any significant impact on species diversification in this group, contrary to the second one. We then reconstructed ancestral states for perianth symmetry in angiosperms as a whole, using a sampling strategy aimed at capturing all of the transitions in this character. We found a minimum of 130 origins of bilateral symmetry, followed by 69 subsequent reversals to radial symmetry. Lastly, the same approach was extended to the study of four other perianth characters. Different ancestral state reconstruction models were used on a phylogenetic tree of 1232 species to test the influence of model changes on reconstructed ancestral states. Our results show that changes in reconstruction models have an impact on the inferred ancestral state of some nodes, but not all of them. The various results obtained for symmetry, a character shared among the three chapters, indicate that our sampling method has the drawback of estimating transition rates too high to give conclusive results with maximum likelihood. On the other hand, results are much less biased when several characters are examined simultaneously
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Branco, Diana Santos 1983. "Sinalização por carboidratos em cana-de-açucar e divergencia evolutiva." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317165.
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Orientadores: Michel Georges Albert Vincentz, Juliana de Maria FelixDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo:Além de fonte primária de carbono e energia para os principais tipos celulares, os açúcares produzidos pela fotossíntese adquiriram importantes funções ao longo da evolução das plantas, no controle do crescimento e desenvolvimento, do metabolismo e na resistência a estresses abióticos (osmótico, energético) e bióticos (potógenos). Os açúcares atuam como sinalizadores ativando cascatas de transdução e, desta forma, promovendo mudanças na programação da expressão gênica. Com o objetivo de entendermos como a sinalização por açúcares diversificou-se em angiospermas, iniciamos uma análise comparativa dos perfis de expressão gênica em resposta aos açúcares sacarose e glicose em plântulas da monocotiledônea Saccharum spp e da eudicotiledônea Arabidopsis thaliana. Para tanto, duas abordagens foram utilizadas. O primeiro aspecto do trabalho estabeleceu relações entre elementos de resposta rápida (resposta primária) a açúcar e acúmulo de sacarose em genótipos de cana contrastantes para teor de sacarose. Outra abordagem, mais abrangente, procurou identificar genes diferencialmente expressos em resposta à sacarose. Na primeira parte do trabalho, a análises por qRT-PCR revelaram uma clara relação entre genes envolvidos em acúmulo de sacarose em cana-de-açúcar e sinalização primária por carboidratos. A partir de 34 SAS (Sugarcane Assembled Sequence) testados envolvidos em acúmulo de sacarose em cana, 24 deles também foram responsivos à glicose e/ou sacarose, sendo que 9 deles responderam em um mesmo sentido em genótipos de cana-de-açúcar que acumulam maior quantidade de sacarose (alto Brix). Dos 24 SAS responsivos à sacarose e/ou glicose, apenas 6 deles apresentaram genes ortólogos em Arabidopsis thaliana cuja regulação por estes açúcares ocorreu de maneira similar. Dentre eles, temos o fator de transcrição IAA16, que se mostrou reprimido por sacarose e glicose, constituindo um possível gene de interação entre sinalização por açúcares e auxina. Duas SNFs quinases parálogas de cana-de-açúcar tem como ortólogo um único gene de Arabidopsis thaliana. Os três genes foram reprimidos por sacarose e glicose, sendo outra parte conservada, na via de sinalização a açúcares entre as duas espécies. Outro gene de particular interesse corresponde a uma deidrina, reprimida por sacarose e glicose em cana, assim como seu ortólogo em Arabidopsis e genótipos alto Brix, sugerindo importante papel deste gene em processos relacionados a sinalização/acúmulo de sacarose. Na segunda parte do trabalho, utilizando-se a técnica de microarranjos de cDNA a partir do chip SUCAST, encontramos 55 genes diferencialmente expressos em resposta à sacarose. Destes, apenas 3 apresentaram genes ortólogos de Arabidopsis regulados por açúcar num mesmo sentido que em cana, correspondentes a duas proteínas quinases e a um gene pseudo-response-regulator. Este estudo preliminar identificou genes conservados da sinalização por açúcares em angiospermas que representam possíveis nós importantes das redes de controle relacionadas a carboidratos. O estabelecimento de um possível envolvimento de alguns destes genes no controle da capacidade de acumular mais sacarose no colmo da cana, abriu novas perspectivas na análise molecular desta importante característica. Estudos mais abrangentes são necessários para melhorar os conhecimentos sobre o grau de diversificação da sinalização por açúcares em angiospermas e os valores adaptativos associados.
Abstract: Besides act as carbon primary source in the major types of cells, sugars produced by photosynthesis acquired important functions in the course of plant's evolution like controlling growth, development, and metabolism and acting in resistance to abiotic and biotic stresses like osmotic, energetic and response to pathogens. Sugars can be signals that active signal transduction pathways to change genes expression programs. In order to access the diversification of sugar pathway signaling in angiosperms we conduct comparative analysis of the gene expression in response to sucrose and glucose in seedlings of the monocot Saccharum sp. and the eudicot Arabidopsis thaliana. We also aimed to access the possible correlation between genes related to sucrose storage in sugar-cane and genes related to primary sugar responses. Another aim was to identify deferentially expressed genes in sucrose response. A clearly relation between genes related to sucrose storage in sugar-cane and quickly primary response to sugars was obtained by qRT-PCR analysis. We tested 34 SAS (Sugar Assembled Sequence) related to sucrose storage in sugar-cane and we found that 24 of them were responsive to glucose and/or sucrose. Nine genes showed the same expression pattern (induction or repression) in response to sugar as seen in high Brix genotypes. Six, of this 24 genes, have Arabidopsis orthologues regulated in the same direction (induced or repressed). One is an IAA16 transcription factor that is repressed by both, glucose and sucrose, and may play a role in an integrative pathway of sugar and auxin responses. We also find two SNFs kinases (paralogues) related to a single Arabidopsis ortholog showing the repression response. Another interesting gene is a dehydrin that was repressed in response to sucrose and glucose in sugar-cane and Arabidopsis (its ortholog) and in the high Brix sugar-cane genotypes. It suggests an important role for this dehydrin in processes related to sucrose signaling and storage. In the second part of this work, the sugar-cane cDNA microarray chip, called SUCAST, allow us to identify 55 deferentially expressed in response to sucrose. Only three of these genes have orthologues regulated in same way in sugar-cane and Arabidopsis. These genes correspond to two protein-kinase and a pseudo-response regulator. This preliminary approach leads us to identify conserved genes in sugar signaling among angiosperms that possibly represents important nodes in the regulatory networks in response to sugars. Establishing the involvement of some of these genes in the ability of sucrose storage in sugar-cane's culm will lead us to new perspectives in the molecular basis of this characteristic. More specific works are also needed to improve the knowledge about the real degree of evolutive diversification in sugar signaling among angiosperms and associated genetic fitness.
Mestrado
Genetica Vegetal e Melhoramento
Mestre em Genética e Biologia Molecular
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Martins, Aline Cristina. "Abelhas coletoras de óleo e suas interações com as flores de Plantaginaceae produtoras de óleo floral." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/59/59131/tde-23042010-154006/.
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Os óleos florais são os recursos alternativos ao pólen e néctar oferecidos por onze famílias de angiospermas às abelhas coletoras de óleo. A produção deste recurso surgiu ao menos 28 vezes e a coleta destes, em cinco linhagens distintas entre as abelhas. Na região Neotropical, Malpighiaceae é a família mais diversa e melhor conhecida em termos de seu sistema de polinização e relação com abelhas coletoras de óleo. Plantaginaceae é conhecida por alguns trabalhos, focados principalmente em Angelonia e Monttea. No presente estudo, são apresentadas as relações entre abelhas coletoras de óleo e flores de Plantaginaceae (cinco espécies de Angelonia e uma de Basistemon), com especial atenção aos aspectos morfológicos de ambos, aspectos comportamentais das abelhas durante a coleta e a sobreposição geográfica entre os parceiros deste mutualismo. Este trabalho apresenta pela primeira vez dados dos visitantes de três espécies: A. eriostachys, A. goyazensis e Basistemon silvaticus; além de dados inéditos sobre espécies já estudadas: A. cornigera, A. integerrima e A. salicariifolia. Foi observado que as estruturas especializadas presentes no labelo de todas as espécies estudadas de Angelonia estão associadas à imposição da postura correta do visitante e sua fixação na flor. As flores de Basistemon são mais simples neste sentido e apresentam apenas um discreto calo mediano. Apesar da morfologia destas estruturas diferirem consideravelmente entre as espécies, é possível estabelecer relações de origem entre elas. A assembléia de visitantes das flores de Angelonia e Basistemon variou entre três a dezoito espécies. Estas espécies foram consideradas polinizadoras ou visitantes ilegítimos. As abelhas do gênero Centris foram consideradas as principais polinizadoras das plantas estudadas, porém, espécies de Tapinotaspidini, em especial o gênero Caenonomada, também detêm esse papel. As abelhas que coletam óleo também coletam pólen, com exceção dos gêneros Centris, Caenonomada e Tapinotaspis, que coletam apenas óleo. O comportamento adequado dos polinizadores de Angelonia e Basistemon, imposto pela morfologia floral, implica na coleta do óleo com as pernas anteriores e o contato com os órgãos férteis na fronte ou mesoscuto em flores com corola mais profunda. Algumas espécies estão morfologicamente adaptadas a coleta nestas flores, como exemplo, as abelhas Centris grupo hyptidis, que possuem aparatos coletores divergentes de todo o padrão apresentado pelo gênero. Quanto à distribuição destas plantas e de seus potenciais polinizadores, em alguns casos, há grande sobreposição e os potenciais polinizadores podem ou não ser especialistas nestas fontes de óleo. Os casos de baixa congruência geográfica mostram que muitos destes potenciais polinizadores não dependem das fontes de óleo de Angelonia e Basistemon.Floral oils are alternative flower reward to pollen and nectar that are offered by eleven families of angiosperms to oil-collecting bees. The production of this resource appeared at least 28 times, and its collection has been observed in five different lineages of bees. In the Neotropical Region, Malpighiaceae is the most diverse and best known family concerning to the pollination system and the interactions with oil-collecting bees. Plantaginaceae is well known due to some studies mostly on Angelonia and Monttea. In this study, the relationship between the oil-collecting bees and the Plantaginaceae flowers (five species of Angelonia and one of Basistemon) is presented, being given special attention to the morphological aspects of both, the bees behavior during the oil collection and the geographical overlap between the partners of this mutualism. This work presents for the first time the visitors of three species (A. eriostachys, A. goyazensis and Basistemon silvaticus), as well as new data on already studied species (A. cornigera, A. integerrima and A. salicariifolia). It was recorded that the specialized structures that are found on the lip (labellum) of all the known species of Angelonia are associated to the imposition of the correct posture of the visitor and their fixation on the flower. The Basistemon flowers are, in this way, less complex and they present only a discrete median callus. Although the morphology of these structures differ considerably among species, it is possible to establish relationships between their origins. The assemblage of visitors of the flowers of Angelonia and Basistemon varied from three to eighteen species. These species were considered pollinators or illegitimate visitors of the studied species. The bees of the genus Centris were considered the main pollinators of these plants; however species of Tapinotaspidini also play this role. These bees collect oil and pollen, in most species, having as exceptions the genera Centris, Caenonomada e Tapinotaspis that collect only oil. The correct behavior of the visitors of Angelonia and Basistemon flowers, imposed by the floral morphology, results the collection of oil with the forelegs and the contact of their fertile organs with their anterior head or dorsal thorax (in flowers with deep corolla). Some species are morphologically adapted to sample in these flowers, for example, the Centris bees group hyptidis, that have collecting apparatus that diverge from the pattern found in the genera. In respect to the distribution of these plants and their potential pollinators, in some cases, there is a large overlap and the potential pollinators may or may not be specialists in these oil sources. The cases of low geographical congruency show that many of these potential pollinators do not depend only on the oil sources of Angelonia and Basistemon.
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Behera, Jyoti, and Aruna Kilaru. "Comparative in Silico Analysis of WRINKLED1 Paralogs in Angiosperms." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7723.
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Behera, Jyoti, Shina Bhatia, and Aruna Kilaru. "Comparative in Silico Analysis of WRINKLED1 Paralogs in Angiosperms." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etsu-works/7724.
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WRINKLED 1(WRI1), a member of AP2/EREBP class of transcription factors regulates carbon allocation between glycolytic and fatty acid biosynthetic pathway. Additionally, among the four WRI1 paralogs in Arabidopsis, WRI3 and 4 but not WRI2, are also able to increase fatty acid content in different tissues. While the role of WRI1 is well established in seeds, the potential or WRI1 or its paralogs as master regulators in oilrich nonseed tissues is poorly understood. Recent transcriptome studies of avocado (Persea americana) mesocarp revealed that the ortholog of WRI2, along with WRI1 and WRI3 was highly expressed during oil accumulation.Through transient expression assays, wefurther demonstrated thatbothPaWRI1 andPaWRI2 can accumulate oil in tobacco leaves. We conducted a comprehensive and comparative in silico analysis of WRI paralogs from a dicot, monocot and a basal angiosperm to identify distinct features associated with function. These data provide insights into the possible evolutionary changes in WRI1 homologs and allow for identification of new targets to enhance oil biosynthesis in diverse tissues.
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Fagundes, Paula Braga. "Um lugar ao sol : a influência do fator histórico sobre o nicho de luz e respostas ecofisiológicas de plantas com semente da floresta ombrófila mista." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/90470.
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Em ambientes florestais, a luz é o recurso que com mais frequência limita o crescimento, a sobrevivência e a reprodução em plantas. Assim, a variação na disponibilidade de luz no sub-bosque influencia a composição local de espécies lenhosas, que se segregam em diferentes nichos de luz de acordo com suas preferências e tolerâncias, conferidas através de suas adaptações e plasticidade fenotípica. Os atributos das espécies atuais, além de serem adaptados ao ambiente onde vivem, são um legado de seus ancestrais, motivo pelo qual espécies mais próximas filogeneticamente, com frequência compartilham atributos semelhantes e, por consequência, ocupam nichos similares, padrão conhecido como conservação filogenética. Estudos recentes mostram que atributos funcionais relacionados à captação de luz teriam se diversificado através de diferentes grupos filogenéticos, conferindo a estes capacidades distintas para a conquista de novos ambientes de luz. Nosso trabalho teve como objetivo detectar a presença de padrões filogenéticos na distribuição e nas respostas ecofisiológicas de oito espécies lenhosas co-ocorrentes e de seus respectivos clados em um sub-bosque florestal, a partir da comparação do nicho de luz e do desempenho de plantas juvenis em resposta ao gradiente luminoso existente. Assim nossas hipóteses são de que 1) as espécies filogeneticamente próximas tem maior semelhança em estratégias adaptativas do que espécies filogeneticamente distantes; 2) a amplitude de nicho e 3) a plasticidade de atributos em resposta à luz aumentam em clados mais derivados. Os resultados apresentados aqui mostraram uma maior similaridade entre as espécies mais relacionadas do que entre aquelas que são filogeneticamente distantes, sugerindo conservação filogenética do nicho. Quanto à amplitude de nicho, também há uma influência filogenética, porém, contrário ao esperado, os clados mais antigos apresentaram um nicho mais amplo. Para a plasticidade dos atributos os resultados aqui apresentados mostram que não há padrões filogenéticos na plasticidade das respostas de espécies e clados estudados, sugerindo o efeito de outros fatores sobre a plasticidade das plantas, como efeitos ontogenéticos ou estresse ambiental.In forest environments, light is the resource that most often limits the growth, survival and reproduction in plants. Thus, the variation in light availability, regarded as one of the most important resources for woody plants in the understory, results in differences in species composition, which segregate in different light niches according to their preferences and tolerances, conferred by their adaptations and phenotypic plasticity. Extant plant traits are not only adapted to the present environment, they are also a legacy from their ancestors and, for that reason, phylogenetically related species often share similar attributes and consequently occupy similar niches, pattern known as phylogenetic conservatism. Recent studies show that functional traits related to the capture of this resource have diversified across different phylogenetic groups, giving them distinct abilities to occupy new light environments. The present study aimed to detect the presence of phylogenetic patterns in species distribution along a light gradient and in ecophysiological responses of eight co-occurring woody species and their respective clades in a forest understory. This was accomplished by comparing the light niche of juvenile plants in response to the existing light gradient, as well as their physiological plasticity in response to understory light variations. We hypothesized that (1) phylogenetic related species have greater similarity of adaptive strategies, and consequently of their niche, than more distantly related ones; and that (2) the niche breadth is wider and (3) traits plasticity is greater in more recent than in more basal clades. The results presented here showed that there is a greater niche similarity between closely related species than between those that are phylogenetically distant, suggesting niche conservatism. Regarding to niche amplitude, there is also a phylogenetic influence but, contrary to our expectations, the older clades showed a greater niche breadth. For plasticity of selected plant traits, results showed no phylogenetic pattern for the studied species and clades, suggesting that other factors act on the phenotypic plasticity of plants, such as ontogenetic effects and/or environmental stress.
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Carpenter, Kevin Joseph. "Structure and evolution of the leaf epidermis in basal angiosperms /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Full textBooks on the topic "Angiosperms"
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Meeuse, A. D. J. All about angiosperms. Delft [The Netherlands]: Eburon, 1987.
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Wang, Xin. The Dawn Angiosperms. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-58325-9.
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Wang, Xin. The Dawn Angiosperms. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01161-0.
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Johri, Brij M., Kunda B. Ambegaokar, and Prem S. Srivastava. Comparative Embryology of Angiosperms. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-76395-3.
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E, Soltis Douglas, ed. Phylogeny and evolution of angiosperms. Washington: Smithsonian Books, 2005.
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1955-, Atri N. S., ed. Germplasm diversity and evaluation: Angiosperms. Dehra Dun: Bishen Singh Mahendra Pal Singh, 2009.
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1955-, Atri N. S., ed. Germplasm diversity and evaluation: Angiosperms. Dehra Dun: Bishen Singh Mahendra Pal Singh, 2009.
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1955-, Atri N. S., ed. Germplasm diversity and evaluation: Angiosperms. Dehra Dun: Bishen Singh Mahendra Pal Singh, 2009.
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1955-, Atri N. S., ed. Germplasm diversity and evaluation: Angiosperms. Dehra Dun: Bishen Singh Mahendra Pal Singh, 2009.
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E, Soltis Douglas, ed. Phylogeny and evolution of angiosperms. Sunderland, MA: Sinauer Associates, 2005.
Find full textBook chapters on the topic "Angiosperms"
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Russell, S. D. "Fertilization in Angiosperms." In Plant Developmental Biology - Biotechnological Perspectives, 283–300. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02301-9_14.
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Spencer, Kenneth A. "Division MAGNOLIOPHYTA (Angiosperms)." In Host Specialization in the World Agromyzidae (Diptera), 17–380. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1874-0_4.
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de M. B. Borin, Maria Renata, and Otto R. Gottlieb. "Chemodiversity of Angiosperms." In ACS Symposium Series, 188–98. Washington, DC: American Chemical Society, 1995. http://dx.doi.org/10.1021/bk-1995-0588.ch016.
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Owfi, Reza E. "Spermatophytes: Angiosperms, Monocotyledons." In Natural Products and Botanical Medicines of Iran, 177–98. First edition. | Boca Raton : CRC Press, 2020. | Series: Natural products chemistry of global plants: CRC Press, 2020. http://dx.doi.org/10.1201/9781003008996-5.
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Bahadur, Bir, T. Pullaiah, and K. V. Krishnamurthy. "Angiosperms: An Overview." In Plant Biology and Biotechnology, 361–83. New Delhi: Springer India, 2015. http://dx.doi.org/10.1007/978-81-322-2286-6_15.
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Hojsgaard, Diego, and Thammineni Pullaiah. "Apomixis in Angiosperms." In Apomixis in Angiosperms, 149–59. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003088561-8.
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Dehgan, Bijan. "ANGIOSPERMS: FLOWERING PLANTS." In Garden Plants Taxonomy, 173–603. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11561-5_4.
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Wang, Xin. "Introduction." In The Dawn Angiosperms, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01161-0_1.
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Wang, Xin. "Appendix." In The Dawn Angiosperms, 195–212. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01161-0_10.
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Wang, Xin. "Suggested Angiosperm Ancestors." In The Dawn Angiosperms, 5–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-01161-0_2.
Full textConference papers on the topic "Angiosperms"
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Labandeira, Conrad, Lifang Xiao, Yair Ben-Dov, S. Augusta Maccracken, Chungkun Shih, David Dilcher, and Dong Ren. "MEALYBUGS AND OTHER SCALE INSECTS OF EARLY CRETACEOUS ANGIOSPERMS." In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-367610.
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Labandeira, Conrad C. "GYMNOSPERMS, ANGIOSPERMS AND INSECT POLLINATORS TRANSITING THE ALBIAN-APTIAN GAP." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-317578.
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Juan-Vicedo, Jorge, and Simón Frean-Marco. "A critical review on the conservation of Pacific marine angiosperms." In MOL2NET'22, Conference on Molecular, Biomedical & Computational Sciences and Engineering, 8th ed. - MOL2NET: FROM MOLECULES TO NETWORKS. Basel, Switzerland: MDPI, 2022. http://dx.doi.org/10.3390/mol2net-08-12746.
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Huang, Yu-Yuan, Yan-Hua Han, Li-Jun Wei, and Jia-Zhuo Wang. "Comparative Studies of Tracheary Element Structure of Some Gymnosperms with Angiosperms." In CYCAD 2011. The New York Botanical Garden Press, 2018. http://dx.doi.org/10.21135/893275389.002.
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Retallack, Greg. "EARLY CRETACEOUS ICE AGES FROM WEATHERING AND BIOMASS OF MIGRATING ANGIOSPERMS." In GSA Connects 2023 Meeting in Pittsburgh, Pennsylvania. Geological Society of America, 2023. http://dx.doi.org/10.1130/abs/2023am-388579.
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Rawat, Siddharth, Juan T. Bejar, and Anna Wang. "Measuring the lipid content in angiosperms using in-line digital holographic microscopy." In Holography: Advances and Modern Trends VIII, edited by Antonio Fimia and Miroslav Hrabovský. SPIE, 2023. http://dx.doi.org/10.1117/12.2662803.
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Kenchanmane Raju, Sunil. "DNA methylation signatures associated with evolutionary fates of duplicated genes across angiosperms." In ASPB PLANT BIOLOGY 2020. USA: ASPB, 2020. http://dx.doi.org/10.46678/pb.20.1053077.
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Chen, Rui. "Leaving angiosperms to diversify on conifers in aphid — a case in Lachninae." In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.107862.
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Tripp, M., W. Rickard, J. Whiteside, P. Gadd, and K. Grice. "Exceptionally Well-Preserved Cutin in Extinct Seed Ferns (Carboniferous): Are these Early Angiosperms?" In 29th International Meeting on Organic Geochemistry. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201902686.
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Frolov, А. О., and I. V. Enushchenko. "The first discovery leaves of angiosperms in the Middle Jurassic deposits in Eastern Siberia." In Problems of studying the vegetation cover of Siberia. TSU Press, 2020. http://dx.doi.org/10.17223/978-5-94621-927-3-2020-42.
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There is fossil of linear whole-marginal leaves with parallel venation in the Middle Jurassic (Aalenian) sediments of the Irkutsk Coal Basin, were found. During the study of cuticle preparations it was found that leaves were steam-bearing, has anastomoses between veins, anomocytic stomata and the diamond-shaped main cells of the epidermis. Such a combination of characters is widespread in modern monocotyledonous and is absent among fossil as well as modern sporeals and gymnosperms plants. We have every reason to believe that we have found unique structures of leaves characteristic of monocotyledons. This find is the oldest among the herbaceous angiosperms of the Jurassic period, such as Yuraherba and Yukhaniya, and the first found in Siberia.
Reports on the topic "Angiosperms"
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Ostersetzer-Biran, Oren, and Jeffrey Mower. Novel strategies to induce male sterility and restore fertility in Brassicaceae crops. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604267.bard.
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Abstract Mitochondria are the site of respiration and numerous other metabolic processes required for plant growth and development. Increased demands for metabolic energy are observed during different stages in the plants life cycle, but are particularly ample during germination and reproductive organ development. These activities are dependent upon the tight regulation of the expression and accumulation of various organellar proteins. Plant mitochondria contain their own genomes (mtDNA), which encode for rRNAs, tRNAs and some mitochondrial proteins. Although all mitochondria have probably evolved from a common alpha-proteobacterial ancestor, notable genomic reorganizations have occurred in the mtDNAs of different eukaryotic lineages. Plant mtDNAs are notably larger and more variable in size (ranging from 70~11,000 kbp in size) than the mrDNAs in higher animals (16~19 kbp). Another unique feature of plant mitochondria includes the presence of both circular and linear DNA fragments, which undergo intra- and intermolecular recombination. DNA-seq data indicate that such recombination events result with diverged mitochondrial genome configurations, even within a single plant species. One common plant phenotype that emerges as a consequence of altered mtDNA configuration is cytoplasmic male sterility CMS (i.e. reduced production of functional pollen). The maternally-inherited male sterility phenotype is highly valuable agriculturally. CMS forces the production of F1 hybrids, particularly in predominantly self-pollinating crops, resulting in enhanced crop growth and productivity through heterosis (i.e. hybrid vigor or outbreeding enhancement). CMS lines have been implemented in some cereal and vegetables, but most crops still lack a CMS system. This work focuses on the analysis of the molecular basis of CMS. We also aim to induce nuclear or organellar induced male-sterility in plants, and to develop a novel approach for fertility restoration. Our work focuses on Brassicaceae, a large family of flowering plants that includes Arabidopsis thaliana, a key model organism in plant sciences, as well as many crops of major economic importance (e.g., broccoli, cauliflower, cabbage, and various seeds for oil production). In spite of the genomic rearrangements in the mtDNAs of plants, the number of genes and the coding sequences are conserved among different mtDNAs in angiosperms (i.e. ~60 genes encoding different tRNAs, rRNAs, ribosomal proteins and subunits of the respiratory system). Yet, in addition to the known genes, plant mtDNAs also harbor numerous ORFs, most of which are not conserved among species and are currently of unknown function. Remarkably, and relevant to our study, CMS in plants is primarily associated with the expression of novel chimericORFs, which likely derive from recombination events within the mtDNAs. Whereas the CMS loci are localized to the mtDNAs, the factors that restore fertility (Rfs) are identified as nuclear-encoded RNA-binding proteins. Interestingly, nearly all of the Rf’s are identified as pentatricopeptide repeat (PPR) proteins, a large family of modular RNA-binding proteins that mediate several aspects of gene expression primarily in plant organelles. In this project we proposed to develop a system to test the ability of mtORFs in plants, which are closely related to known CMS factors. We will induce male fertility in various species of Brassicaceae, and test whether a down-relation in the expression of the recombinantCMS-genes restores fertility, using synthetically designed PPR proteins.
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Joel, Daniel M., John C. Steffens, and Alfred M. Mayer. Host-Elicited Germination and Mechanism of Penetration in Broomrape (Orobanche Spp.). United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568107.bard.
Full textAbstract:
Orobanche is an important parasitic weed. For developing novel methods for its control, a thorough understanding of crucial stages of its development is needed. Therefore, the objectives of this project were characterization of Orobanche germination stimulants, analysis of mechanisms of haustorial penetration, and characterization and isolation of penetration enzymes. The first highly potent natural germination stimulant for Orobanche was isolated from sunflower and identified by high-field 1D (1H and 13C), 2D (1H-1H COSY, HMQC, HMBC)-NMR, GC.FT-IR, and GC.MS as costuslactone, a guaiane type sesquiterpene lactone that resembles strigol only in possessing a lactone moiety that is required for activity. The first direct in situ evidence for the enzymatic nature of the infection process of a parasitic angiosperm was established. Pectin deesterification and depletion of pectins in host cell walls were shown adjacent to haustorial cells. Pectin methyl esterase and polygalacturonase were immunocytochemically detected in intrusive cells and in adjacent host apoplast. Orobanche tissues contain inhibitors of PGase activity. PME and three PGases were isolated from Orobanche calli. PME was characterized and purified, and antibodies were prepared against it. This study presents novel findings regarding parasitism in Orobanche, which may help to open up new approaches for controlling broomrapes.
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Cenomanian angiosperm leaf megafossils, Dakota Formation, Rose Creek locality, Jefferson County, southeastern Nebraska. US Geological Survey, 1990. http://dx.doi.org/10.3133/b1915.
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