158,111 research outputs found

    The Arabidopsis thaliana checkpoint kinase WEE1 protects against premature vascular differentiation during replication stress

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    A sessile lifestyle forces plants to respond promptly to factors that affect their genomic integrity. Therefore, plants have developed checkpoint mechanisms to arrest cell cycle progression upon the occurrence of DNA stress, allowing the DNA to be repaired before onset of division. Previously, the WEE1 kinase had been demonstrated to be essential for delaying progression through the cell cycle in the presence of replication-inhibitory drugs, such as hydroxyurea. To understand the severe growth arrest of WEE1-deficient plants treated with hydroxyurea, a transcriptomics analysis was performed, indicating prolonged S-phase duration. A role for WEE1 during S phase was substantiated by its specific accumulation in replicating nuclei that suffered from DNA stress. Besides an extended replication phase, WEE1 knockout plants accumulated dead cells that were associated with premature vascular differentiation. Correspondingly, plants without functional WEE1 ectopically expressed the vascular differentiation marker VND7, and their vascular development was aberrant. We conclude that the growth arrest of WEE1-deficient plants is due to an extended cell cycle duration in combination with a premature onset of vascular cell differentiation. The latter implies that the plant WEE1 kinase acquired an indirect developmental function that is important for meristem maintenance upon replication stress

    The whole and its parts : why and how to disentangle plant communities and synusiae in vegetation classification

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    Most plant communities consist of different structural and ecological subsets, ranging from cryptogams to different tree layers. The completeness and approach with which these subsets are sampled have implications for vegetation classification. NonÔÇÉvascular plants are often omitted or sometimes treated separately, referring to their assemblages as ÔÇťsynusiaeÔÇŁ (e.g. epiphytes on bark, saxicolous species on rocks). The distinction of complete plant communities (phytocoenoses or holocoenoses) from their parts (synusiae or merocoenoses) is crucial to avoid logical problems and inconsistencies of the resulting classification systems. We here describe theoretical differences between the phytocoenosis as a whole and its parts, and outline consequences of this distinction for practise and terminology in vegetation classification. To implement a clearer separation, we call for modifications of the International Code of Phytosociological Nomenclature and the EuroVegChecklist. We believe that these steps will make vegetation classification systems better applicable and raise the recognition of the importance of nonÔÇÉvascular plants in the vegetation as well as their interplay with vascular plants

    Vascular plants flora of the railway grounds of Łask

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    In the paper a list and general characterization of vascular plants flora recorded on railway grounds of ┼üask is presented. The great diversity of habitats within the railway grounds as well as their readiness to accept numerous introduced species result in high variety of vascular plants there. This flora consists of 369 taxa.Zadanie pt. ÔÇ×Digitalizacja i udost─Öpnienie w Cyfrowym Repozytorium Uniwersytetu ┼ü├│dzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet ┼ü├│dzkiÔÇŁ nr 885/P-DUN/2014 dofinansowane zosta┼éo ze ┼Ťrodk├│w MNiSW w ramach dzia┼éalno┼Ťci upowszechniaj─ůcej nauk─Ö

    Vascular plants flora of the railway grounds of Zduńska Wola

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    In the paper a list and general characterization of vascular plants flora recorded on railway grounds in the city of Zdu┼äska W ola is presented. The great diversity of habitats within the railway grounds as well as their readiness to accept numerous introduced species result in a high variety of vascular plants there. This flora consists of 366 taxa.Zadanie pt. ÔÇ×Digitalizacja i udost─Öpnienie w Cyfrowym Repozytorium Uniwersytetu ┼ü├│dzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet ┼ü├│dzkiÔÇŁ nr 885/P-DUN/2014 dofinansowane zosta┼éo ze ┼Ťrodk├│w MNiSW w ramach dzia┼éalno┼Ťci upowszechniaj─ůcej nauk─Ö

    Natural Areas and Reference Collections for Environmental Education in Some Arkansas Schools

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    A survey of 20 school campuses throughout Arkansas showed that most lack natural areas for outdoor environmental education. For most Arkansas schools no checklists of local plants are available, and there are no reference collections at the schools. Projects are underway at State College of Arkansas to establish herberia for the woody plants of Arkansas and the vascular plants of Faulkner County

    Characteristics of C-4 photosynthesis in stems and petioles of C-3 flowering plants

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    Most plants are known as C-3 plants because the first product of photosynthetic CO2 fixation is a three-carbon compound. C-4 plants, which use an alternative pathway in which the first product is a four-carbon compound, have evolved independently many times and are found in at least 18 families. In addition to differences in their biochemistry, photosynthetic organs of C-4 plants show alterations in their anatomy and ultrastructure. Little is known about whether the biochemical or anatomical characteristics of C-4 photosynthesis evolved first. Here we report that tobacco, a typical C-3 plant, shows characteristics of C-4 photosynthesis in cells of stems and petioles that surround the xylem and phloem, and that these cells are supplied with carbon for photosynthesis from the vascular system and not from stomata. These photosynthetic cells possess high activities of enzymes characteristic of C-4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis. These biochemical characteristics of C-4 photosynthesis in cells around the vascular bundles of stems of C-3 plants might explain why C-4 photosynthesis has evolved independently many times

    Plant Transcription Factors @ uni-potsdam.de

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    We present the Plant Transcription Factor Database (PlnTFDB), and the putative complete set of TFs in the algae _Chlamydomonas reinhardtii_, _Ostreococcus tauri_ and the vascular plants _Oryza sativa_ and _Arabidopsis thaliana_

    Experiments and operational procedures for developing germ-free seeds, seedlings, plants, tissues and cell lines for the Lunar Receiving Laboratory Final report

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    Germ-free seeds, seedlings, plants, tissues, and cell lines for lunar receiving laboratory, including algal and vascular plant system

    New floristic data of alien vascular plants from Sicily

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    New records of Commelina communis, Euphorbia hypericifolia, Melia azedarach, Nicotiana tabacum, and Xanthoceras sorbifolium are reported for the Sicilian flora
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