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  • Botany 2013 - Aquaporins in stems and roots - tissue level localization and function
    Long distance water transport in the xylem is in essence a physical process Yet in addition to the rapid flow of water between vessels and tracheids there is radial movement of water between growth rings as well as an exchange of water between xylem and phloem Much work has focused on the efficiency of the conduit network in terms of maximizing axial flow or on its vulnerability to cavitation Less is known about radial movement of water and exchange of water between ray cells and vessels Since the latter process involves flow through membranes it will likely be facilitated by aquaporin water channels Using images from immunolabeling and in situ hybridization experiments on poplar and spruce I will show in which cells and tissues aquaporins are present Strong signals occurred in various regions of cross sections including the cambial region phloem and rays Water channels in stems were expressed in a manner that allows hydraulic coupling between xylem and other tissues that may serve as water reservoirs i e bark parenchyma phloem and pith parenchyma cells In the cambial region water channels may help sustain rapid cell division and expansion of developing xylem and phloem cells Broader Impacts Log in

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=134 (2016-02-01)
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  • Botany 2013 - Aquatic plants of the Orinoco basin of Colombia: inventory, plant communities and their habitats
    the Andean foothills and the Guiana shield maintained by the flooding of the Orinoco River and its tributaries This constitutes a complex mosaic of water bodies and wide seasonal wetlands that hold a diverse but poorly known aquatic flora We aimed to catalogue the entire herbaceous flora of the Orinoco Basin of Colombia along flooded savannas Mauritia flexuosa palm swamps rivers lakes streams drained rocky outgrowths river shores and white sand flooded savannas which are the main aquatic habitats that make up the landscape To identify plant associations to specific aquatic habitats we conducted hierarchical cluster analysis Our study included a total of approximately 966 voucher specimens representing 170 identified species in 107 genera and 58 families The best represented genera were Utricularia 12 species and Ludwigia 13 species Hierarchical cluster analysis showed eight clusters of species each one associated to one of the main aquatic habitats mentioned above All the groups included plants that were only found in the associated habitat The first cluster was the most species rich group and included 34 species associated to flooded savannas 16 of which were only found in this habitat Plants within this group are all helophytes like Byttneria scabra and Xyris jupicai The second largest group included 25 helophyte and hydrophyte species mainly associated to streams 14 of them found only in this habitat such as Macarenia clavijera an endemic Podostemaceae The smallest cluster was associated to river shores Our results show that although at first sight the Orinoco basin in Colombia looks like a uniform grass dominated landscape it holds a great amount of aquatic vegetation specific to different habitats Currently the region represents a challenge to conservation due to soy and oil palm plantations as well as petroleum oil exploration and exploitation We hope that our study will contribute

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=383 (2016-02-01)
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  • Botany 2013 - <em>Arabidopsis</em> scaffold protein RACK1A regulates diverse environmental stress signaling pathways
    1 Smalls DeAna 1 Leonard Victor 1 Ullah Hemayet 1 Arabidopsis scaffold protein RACK1A regulates diverse environmental stress signaling pathways RACK1 Receptor for Activated C Kinase 1 is a WD 40 scaffold protein conserved in eukaryotes In the model plant Arabidopsis thaliana the genome maintains three different RACK1 genes termed RACK1A RACK1B and RACK1C with a very high 85 93 sequence conservation Loss of function mutants in Arabidopsis indicate that RACK1 proteins regulate environmental stress signaling pathways namely the drought stress resistance pathway RACK1A the predominant isoform is found to interact with diverse environmental stress related proteins Deduced crystal structure of RACK1A indicates that post translational modifications like sumoylation and phosphorylation can regulate its function Tyrosine phosphorylation on residue 248 is found to regulate its homo dimerization capacity as well as its interactions with other proteins Kundu et al 2013 Small compounds inhibiting Y248 phosphorylations are isolated and the effectiveness of the compounds in regulating diverse environmental stress responses by the model plant Arabidopsis are evaluated Here we present evidence that the compounds are effective in regulating salt and drought stress responses in Arabidopsis Broader Impacts Log in to add this item to your schedule 1 Howard University Biology Department

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=506 (2016-02-01)
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  • Botany 2013 - Architecture of three <em>Lupinus</em> life forms in the Colombian Andes
    clade displays a variety of life forms growth habits which in combination with other adaptive strategies help the plant in dealing with tropical high elevation environments Many studies and descriptions of the architecture in crop species of Lupinus have been performed seeking for a better yield However life form variation remains poorly documented or undocumented for non cultivated species Here we describe and look for the principal differences in the architecture of three life forms of Lupinus found in the Colombian Andes The life forms analyzed were erect shrub prostrate shrub and basal acaulescent rosette Although Leeuwenberg s Model is maintained for Lupinus along the different growth habits some architecture patterns vary between them Branching tends to be basitonic in prostrate shrubs mesotonic in erect shrubs and acrotonic in the basal acaulescent rosette A balance between vegetative and reproductive growth is also observed The less orders of ramification the denser the inflorescence as in the basal acaulescent rosette in contrast with the very ramified prostrate shrubs with simpler inflorescences These growth patterns are then the response not only to the genetic background of the group but also to the environment to which they have adapted Broader Impacts Log in to

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=428 (2016-02-01)
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  • Botany 2013 - A re-examination of phenologies in the Vitacaeae
    Vitis and its various cultivars which have been associated with the viticultural industry The purpose and primary function of precisely identifying phenological stages in Vitis is to correlate the timing of specific stages with external and cultural factors such as climate predation and disease control There are many publications devoted to the identification of growths stages for the commercial grapevine reviewed by Coombe 1995 but none have paid much attention to the fact the grapes like most temperate woody plants are proleptic That is the lateral axillary branch in the grapevine demonstrates discontinuous growth with an intervening period of rest Some of the development that will produce this year s grapes occurs during last year s formation of axillary buds We followed the development of the North American native grape Vitis riparia over a two year growth cycle in order to produce a phenology that recognizes the proleptic nature of most temperate grapes Of course the Vitaceae also has many tropical genera where the growth and development of lateral branches is primarily sylleptic In these genera the lateral branch usually floral develop without an evident intervening period of rest Examples of phenologies from several tropical genera including Tetrastigma Cyphostemma and

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=317 (2016-02-01)
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  • Botany 2013 - A review of secondary phloem in Devonian and Mississippian lignophytes.
    is considered one of the key innovations that occurred among vascular plants during the Devonian Unlike secondary xylem secondary phloem is rarely well preserved in the fossil record This is due either to the decay of the unlignified cells that constitute most of the phloem or to the loss of bark tissues decortication before fossilization As a result while some detailed anatomical studies of fossil secondary phloem exist our knowledge of the evolution of this tissue remains incomplete In this talk we will review the secondary phloem anatomy of 11 lignophyte taxa of Devonian and Mississippian age based on both previously published and novel specimens kept in the collections of Montpellier 2 University In Tetraxylopteris and Triloboxylon two genera belonging to the oldest group of lignophytes the aneurophytalean progymnosperms the secondary phloem is a complex tissue containing rays different types of thin walled cells and fibers arranged in radial files Study of large roots and a trunk of Callixylon from the Late Devonian of Morocco show that a comparable organization is found in the inner secondary phloem of archaeoperidalean progymnosperms Among Mississippian lignophytes assigned to the seed plants the genus Calamopitys has a secondary phloem composed of alternating bands of parenchyma and sieve cells with no sclerenchyma Phloem fibers are present in all the other Mississippian genera studied Bilignea Eristophyton Faironia Lyginopitys Stanwoodia and two new taxa from the Early Mississippian of Australia and Algeria respectively In both archaeopteridalean progymnosperms and seed plants different types of phloem cells tend to be produced rhythmically in tangential bands Changes between the inner and outer phloem include an increase in diameter of axial parenchyma cells proliferation of axial parenchyma cells and or enlargement of rays This study of secondary phloem anatomy supports a close relationship between Aneurophytales Archaeopteridales and seed plants At the

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=96 (2016-02-01)
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  • Botany 2013 - A Review of the Taxonomy of African Sapindaceae based on Quantitative and Qualitative Characters
    study was conducted using qualitative and quantitative morphology to characterise and group different representative species of the family Sapindaceae in Africa The morphological characters used included leaf stem and fruit Essentially the similarities among various taxa in the family were estimated A total of 28 genera and 106 species were assessed Members possess compound leaves paripinnate imparipinnate or trifoliolate flowers are in clusters fruits occur as berry drupe or capsule and contain seed with white or orange aril UPGMA dendograms were generated showing relationships amongst taxa studied The dendograms consists of a single cluster from 0 57 similarity coefficients suggesting a single line decent of the members of the family At 65 two clusters were observed with Majidea fosterii being separated from the cluster Also at 67 similarity coefficient two clusters were discerned separating the climbing forms from the shrubby forms Paullinia pinnata was separated from the other climbing forms at 67 while Allophylus species were separated into two clusters at 91 similarity coefficient The dendograms revealed that the family can be separated into eleven 11 clusters based on qualitative morphological data A key to the identification of genera is presented in this work Broader Impacts Log in to add

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=1281 (2016-02-01)
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  • Botany 2013 - A revised and expanded phylogeny of <em>Artocarpus </em>(Moraceae) and its biogeographic implications
    and several floras have used different species circumscriptions Recent phylogenetic reconstruction of the genus using a chloroplast and nuclear marker found that the genus Prainea is nested with Artocarpus and that many of the intrageneric rankings do not represent monophyletic lineages However only 50 of taxa were sampled and many relationships remained unresolved Here we used six chloroplast regions and two nuclear markers matK rbcL trnL F trnS G trnV ndhC trnH psbA ITS G3PDH to present the most complete Artocarpus phylogeny with nearly 75 taxon sampling within the genus and include outgroups representing all proposed Artocarpeae genera as well as taxa from all of the Moraceae tribes We used maximum parsimony maximum likelihood and Bayesian inference on the full partitioned dataset in order to test whether increased taxon sampling and data increased resolution and continued to support the monophyly of Artocarpus We also tested the current generic and intrageneric classifications We found that major divisions within Artocarpus are resolved and supported but some polytomies persist The genus Prainea is confirmed as nested within Artocarpus as suggested by previous studies Replication within taxa also allowed us to examine relationships of subspecies as well as among highly morphologically variable wide ranging

    Original URL path: http://www.2013.botanyconference.org/engine/search/index.php?func=detail&aid=429 (2016-02-01)
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