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    4557 results match your criteria American journal of botany[Journal]

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    Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (×).
    Am J Bot 2017 Dec 15;104(12):1878-1890. Epub 2017 Dec 15.
    Ecology, Evolution and Behavior, University of Minnesota, 140 Gortner Laboratory, 1479 Gortner Avenue, St. Paul, MN 55108 USA.
    Premise Of The Study: Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnantpopulations. Pleistocene hybridization betweenandhas been proposed, but the nearestpopulations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. Read More

    Sexual expression and reproductive output in the ephemeralare correlated with environmental conditions.
    Am J Bot 2017 Dec 15;104(12):1920-1929. Epub 2017 Dec 15.
    Department of Plant Biology, 2502 Plant Sciences Building, University of Georgia, Athens, Georgia 30602, USA
    Premise Of The Study: Abiotic environmental factors are often considered to be important in the distribution and maintenance of variation in sexual systems in flowering plants. Associations between sexes and abiotic factors are well documented in dioecious systems, but much less is known about this relationship in other sexually polymorphic systems. Species that are highly variable in sexual expression and habitat distribution can provide insights into the role of abiotic factors in maintaining variation in sexual expression. Read More

    Evolution of the process underlying floral zygomorphy development in pentapetalous angiosperms.
    Am J Bot 2017 Dec 15;104(12):1846-1856. Epub 2017 Dec 15.
    Department of Biology, Virginia Commonwealth University, 1000 West Cary Street, Richmond, Virginia 23284 USA
    Premise Of The Study: Observations of floral ontogeny indicated that floral organ initiation in pentapetalous flowers most commonly results in a median-abaxial (MAB) petal during early development, a median-adaxial (MAD) petal being less common. Such different patterns of floral organ initiation might be linked with different morphologies of floral zygomorphy that have evolved in Asteridae. Here, we provide the first study of zygomorphy in pentapetalous angiosperms placed in a phylogenetic framework, the goal being to find if the different patterns of floral organ initiation are connected with particular patterns of zygomorphy. Read More

    Pollen-pistil interaction in pawpaw (), the northernmost species of the mainly tropical family Annonaceae.
    Am J Bot 2017 Dec 7;104(12):1891-1903. Epub 2017 Dec 7.
    Department of Subtropical Fruit Crops, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM La Mayora-UMA-CSIC) 29750 Algarrobo-Costa, Málaga, Spain
    Premise Of The Study: The pawpaw,, is an underutilized fruit crop native to North America that belongs to the mainly tropical, early-divergent family the only genus within the Annonaceae with species adapted to cold climates. A thorough analysis of its reproductive biology, specifically pollen-pistil interaction during the progamic phase, is essential to understand both its adaptation to cold climates and how to optimize its fertilization and fruit set. Read More

    More than sixty origins of pantoporate pollen in angiosperms.
    Am J Bot 2017 Dec 7;104(12):1837-1845. Epub 2017 Dec 7.
    Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay 91405 Orsay cedex, France.
    Premise Of The Study: Apertures in pollen grains are key structures of the wall, involved in pollen tube germination and exchanges with the environment. Aperture types in angiosperms are diverse, but pollen with one and three apertures (including monosulcate and tricolpate, respectively) are the two most common types. Here, we investigate the phylogenetic distribution in angiosperms of pollen with many round, scattered apertures called pantoporate pollen. Read More

    Evolutionary history of two pollen self-incompatibility factors reveals alternate routes to self-compatibility within.
    Am J Bot 2017 Dec 6;104(12):1904-1919. Epub 2017 Dec 6.
    C. M. Rick Tomato Genetics Resource Center, Department of Plant Sciences (ms 3), University of California, One Shields Avenue, Davis, California 95616 USA
    Premise Of The Study: Self-incompatibility (SI) prevents self-fertilization and reduces inbreeding. While SI is common in plants, transitions to self-compatibility (SC) occur frequently. Little is known about the genetic changes and evolutionary steps underlying these shifts. Read More

    Passifloraceae seeds from the late Eocene of Colombia.
    Am J Bot 2017 Dec 6;104(12):1857-1866. Epub 2017 Dec 6.
    L.H. Bailey Hortorium, Department of Plant Biology, Cornell University, Ithaca, New York 14850 USA; and The Center for Tropical Paleoecology and Archaeology, Smithsonian Tropical Research Institute, Ancón, Panamá
    Premise Of The Study: The plant fossil record for the neotropics is still sparse and temporally discontinuous. The location and description of new fossil material are fundamental for understanding evolutionary and biogeographic patterns of lineages. A new fossil record of Passifloraceae from the late Eocene of Colombia is described in this study. Read More

    Edaphic history over seedling characters predicts integration and plasticity of integration across geologically variable populations of.
    Am J Bot 2017 Dec 1;104(12):1802-1815. Epub 2017 Dec 1.
    Department of Biology, College of Charleston, Charleston, South Carolina 29424, USA
    Premise Of The Study: Studies on phenotypic plasticity and plasticity of integration have uncovered functionally linked modules of aboveground traits and seedlings of, but we lack details about belowground variation in adult plants. Functional modules can be comprised of additional suites of traits that respond to environmental variation. We assessed whether shoot and root responses to nutrient environments in adultwere predictable from seedling traits or population-specific geologic soil characteristics at the site of origin. Read More

    Vapor pressure deficit predicts epiphyte abundance across an elevational gradient in a tropical montane region.
    Am J Bot 2017 Dec 1;104(12):1790-1801. Epub 2017 Dec 1.
    Franklin and Marshall College, Department of Mathematics, Lancaster, Pennsylvania 17603 USA.
    Premise Of The Study: Tropical Montane Cloud Forests (TMCFs) are important ecosystems to study and preserve because of their high biodiversity and critical roles in local and regional ecosystem processes. TMCFs may be particularly affected by changes in climate because of the narrow bands of microclimate they occupy and the vulnerability of TMCF species to projected increases in cloud base heights and drought. A comprehensive understanding of the structure and function of TMCFs is lacking and difficult to attain because of variation in topography within and across TMCF sites. Read More

    Dynamics of gaps, vegetation, and plant species with and without fire.
    Am J Bot 2017 Dec 1;104(12):1825-1836. Epub 2017 Dec 1.
    Department of Biology, University of Central Florida, Orlando, Florida, USA.
    Premise Of The Study: Areas lacking dominant plants, or gaps, can support high diversity and specialist species. Previous chronosequence research in Florida rosemary scrub showed indistinct gap area patterns with fire and the dependence of certain species on gaps. We hypothesized that fire and gap size would affect extinction, colonization, diversity, and vegetation composition. Read More

    Memoirs of a frequent flier: Phylogenomics reveals 18 long-distance dispersals between North America and South America in the popcorn flowers (Amsinckiinae).
    Am J Bot 2017 Nov 23. Epub 2017 Nov 23.
    Department of Biology, San Diego State University, San Diego, California 92128 USA
    Premise Of The Study: American amphitropical disjunction (AAD) is an important but understudied New World biogeographic pattern in which related plants occur in extratropical North America and South America, but are absent in the intervening tropics. Subtribe Amsinckiinae (Boraginaceae) is one of the richest groups of plants displaying the AAD pattern. Here, we infer a time-calibrated molecular phylogeny of the group to evaluate the number, timing, and directionality of AAD events, which yields generalizable insights into the mechanism of AAD. Read More

    Origins of North American arid-land Verbenaceae: More than one way to skin a cat.
    Am J Bot 2017 Nov 23. Epub 2017 Nov 23.
    Department of Biology and Burke Museum, University of Washington, Seattle, Washington, 98195 USA.
    Premise Of The Study: Verbenaceae originated and initially diversified in South America in wet forest habitats. They have diversified extensively in arid habitats in both South and North America. This study aims to understand the origin of the North American arid-land members of Verbenaceae. Read More

    Parallel Pleistocene amphitropical disjunctions of a parasitic plant and its host.
    Am J Bot 2017 Nov 23. Epub 2017 Nov 23.
    Department of Microbiology and Plant Biology and Oklahoma Biological Survey, University of Oklahoma, 770 Van Vleet Oval, Norman, Oklahoma 73019 USA.
    Premise Of The Study: is a clade of holoparasites that includes closely related North American and South American species parasitic on. Both(Orobanchaceae) and(Asteraceae) have amphitropical disjunctions between North America and South America; however, the timing of these patterns and the processes to explain them are unknown.

    Methods: Chronograms for the Orobanchaceae andand their relatives were constructed using fossil and secondary calibration points, one of which was based on the inferred timing of horizontal gene transfer from a papilionoid legume into the common ancestor ofand. Read More

    Naturally fragmented and isolated distribution in subtropical grassland patches affects genetic diversity and structure at different spatial scales: The case of, an endemic shrub from Brazil.
    Am J Bot 2017 Dec 22;104(12):1867-1877. Epub 2017 Nov 22.
    Programa de Pós-Graduação em Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
    Premise Of The Study: The genetic structure of organisms results from the interactions between life history traits and the ecological and demographic characteristics of the landscape that shape the intra- and interpopulation genetic variation in space and time. In this study, we used a species restricted to islands of grassland vegetation in southern Brazil to investigate the effects of its naturally fragmented distribution on diversity and genetic structure patterns.

    Methods: Diversity and intra- and interpopulational genetic structure were analyzed using polymorphisms of eight nuclear microsatellite markers in 205 individuals ofand Bayesian and multivariate methods. Read More

    Inferring long-distance dispersal modes in American amphitropically disjunct species through adaptive dispersal structures.
    Am J Bot 2017 Nov 22. Epub 2017 Nov 22.
    Department of Biology, Georgia Southern University, Statesboro, Georgia 30460-8042 USA.
    Premise Of The Study: A repeated pattern of American amphitropical disjunct species or sister species distributed on either side of the equator has long-fascinated botanists, but the modes of these disjunctions remain untested. We evaluated diaspore morphology to generate hypotheses on probable dispersal mechanisms.

    Methods: The sizes and structures of diaspores, habit, habitat, distribution, and dispersal units were collected for 108 species from literature searches and herbarium specimens. Read More

    Niche shifts after long-distance dispersal events in bipolar sedges (, Cyperaceae).
    Am J Bot 2017 Nov 22. Epub 2017 Nov 22.
    Department of Plant Biology and Ecology, Universidad de Sevilla, Reina Mercedes 6, ES-41012, Seville, Spain.
    Premise Of The Study: Bipolar species represent the greatest biogeographical disjunction on Earth, raising many questions about the colonization and adaptive processes behind such striking distribution. We investigated climatic niche differences of fivebipolar species in North and South America to assess niche shifts between these two regions. Moreover, we assessed potential distribution changes with future climate change. Read More

    Observations on bipolar disjunctions of moonwort ferns (, Ophioglossaceae).
    Am J Bot 2017 Nov 22. Epub 2017 Nov 22.
    Sitka Sound Science Center, Sitka, Alaska 99835, USA (e-mail:
    Peter Raven, in 1963, included two fern taxa of the genusin his list of plant species exhibiting American amphitropical bipolar disjunctions. He attributed the southern hemisphere occurrences to post-Pleistocene long-distance dispersal from counterparts in the northern hemisphere, probably assisted by annual bird migrations between the disjunct areas. Using genetic evidence gathered through worldwide analyses of phylogenetic relationship in, we now review and reconsider Raven's conclusions. Read More

    Bipolar distributions in vascular plants: A review.
    Am J Bot 2017 Nov 22. Epub 2017 Nov 22.
    Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, carretera de Utrera km 1, ES-41013, Seville, Spain.
    Bipolar disjunct distributions are a fascinating biogeographic pattern exhibited by about 30 vascular plants, whose populations reach very high latitudes in the northern and southern hemispheres. In this review, we first propose a new framework for the definition of bipolar disjunctions and then reformulate a list of guiding principles to consider how to study bipolar species. Vicariance and convergent evolution hypotheses have been argued to explain the origin of this fragmented distribution pattern, but we show here that they can be rejected for all bipolar species, except forInstead, human introduction and dispersal (either direct or by mountain-hopping)facilitated by standard and nonstandard vectorsare the most likely explanations for the origin of bipolar plant disjunctions. Read More

    Rapid root responses of seedlings exposed to a postdrought water pulse.
    Am J Bot 2017 Dec 22;104(12):1816-1824. Epub 2017 Nov 22.
    Schmid College of Science and Technology, Chapman University, Orange, California 92866 USA.
    Premise Of The Study: Mediterranean-type climate ecosystems experience significant variability in precipitation within and across years and may be characterized by periods of extreme drought followed by a brief, high-intensity precipitation pulse. Rapid root growth could be a key factor in effective utilization of precipitation pulses, leading to higher rates of seedling establishment. Changes in root growth rate are rarely studied, however, and patterns in seedling root traits are not well explored. Read More

    Amphitropical disjunctions in New World Menthinae: Three Pliocene dispersals to South America following late Miocene dispersal to North America from the Old World.
    Am J Bot 2017 Nov 20. Epub 2017 Nov 20.
    Department of Botany, University of Wisconsin, Madison, Wisconsin 53706 USA.
    Premise Of The Study: The subtribe Menthinae (Lamiaceae), with 35 genera and 750 species, is among the largest and most economically important subtribes within the mint family. Most genera of Menthinae are found exclusively in the New World, where the group has a virtually continuous distribution ranging from temperate North America to southern South America. In this study, we explored the presence, timing, and origin of amphitropical disjuncts within Menthinae. Read More

    Fates of angiosperm species following long-distance dispersal: Examples from American amphitropical Polemoniaceae.
    Am J Bot 2017 Nov 20. Epub 2017 Nov 20.
    Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California 91711 USA.
    Premise Of The Study: Following establishment after long-distance dispersal, species may experience stasis, accumulate changes leading to new species identity, diversify into multiple species, interact with related species to form novel species, and even become extirpated. We examined each species of temperate Polemoniaceae in South America via the literature and new analyses to better understand the fates of species in this family after their dispersal from North America.

    Methods: We reviewed literature for the 15 species of Polemoniaceae in South America amphitropically disjunct from their relatives in North America. Read More

    The ontogenetic bases for variation in ovary position in Melastomataceae.
    Am J Bot 2017 Aug 21. Epub 2017 Aug 21.
    Universidade de São Paulo (USP), Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Departamento de Ciências Farmacêuticas, Av. do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil
    Premise Of The Study: Although the ovary position is considered a stable character in angiosperms, Melastomataceae species have perigynous flowers in which the ovary varies from superior to inferior. Thus, we investigated the ontogenetic process involved in variation of the ovary position in Melastomataceae. We focused on histogenesis of the floral apex in search of developmental patterns for each type of ovary position. Read More

    Comparative transcriptomics indicate changes in cell wall organization and stress response in seedlings during spaceflight.
    Am J Bot 2017 Aug 21. Epub 2017 Aug 21.
    University of North Carolina at Greensboro, Department of Biology, Greensboro, North Carolina 27412 USA
    Premise Of The Study: Plants will play an important role in the future of space exploration as part of bioregenerative life support. Thus, it is important to understand the effects of microgravity and spaceflight on gene expression in plant development.

    Methods: We analyzed the transcriptome ofusing the Biological Research in Canisters (BRIC) hardware during Space Shuttle mission STS-131. Read More

    Fungal endophyte communities in the temperate fernshow early colonization and extensive temporal turnover.
    Am J Bot 2017 Aug 16. Epub 2017 Aug 16.
    Department of Biology, Portland State University, Portland, Oregon 97201, USA.
    Premise Of The Study: Fungal endophytes have been shown to colonize all land plants, yet surprisingly little attention has been given to their community composition in ferns. We examined the diversity and temporal turnover of fungal endophytes in foliar tissue of the temperate western sword fern,, comparing taxa in newly emerged leaflets and in the same fronds after 1 mo of exposure in the field.

    Methods: Utilizing next-generation sequencing, we sampled pinnae fromin spring, 2-3 d after they emerged. Read More

    Comparative epigenetic and genetic spatial structure of the perennial herb: Isolation by environment, isolation by distance, and functional trait divergence.
    Am J Bot 2017 Aug 16. Epub 2017 Aug 16.
    Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avenida Americo Vespucio 26, 41092 Sevilla, Spain.
    Premise Of The Study: Epigenetic variation can play a role in local adaptation; thus, there should be associations among epigenetic variation, environmental variation, and functional trait variation across populations. This study examines these relationships in the perennial herb(Ranunculaceae).

    Methods: Plants from 10 subpopulations were characterized genetically (AFLP, SSR markers), epigenetically (MSAP markers), and phenotypically (20 functional traits). Read More

    Can asexuality confer a short-term advantage? Investigating apparent biogeographic success in the apomictic triploid fern.
    Am J Bot 2017 Aug 16. Epub 2017 Aug 16.
    Department of Biological Sciences, Wichita State University, Wichita, Kansas 67260 USA
    Premise Of The Study: Although asexual taxa are generally seen as evolutionary dead ends, asexuality appears to provide a short-term benefit in some taxa, including a wider geographic distribution compared to sexual relatives. However, this may be an illusion created by multiple, morphologically cryptic, asexual lineages, each occupying a relatively small area. In this study we investigate the role of multiple lineages in the biogeography ofFée (Pteridaceae), a North American apomictic triploid fern species with a particularly large range. Read More

    Adaptive spatiotemporal changes in morphology, anatomy, and mechanics during the ontogeny of subshrubs with square-shaped stems.
    Am J Bot 2017 Aug 16. Epub 2017 Aug 16.
    Plant Biomechanics Group, Botanic Garden, Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany
    Premise Of The Study: Plant stems can be regarded as fiber-reinforced structures characterized by anatomical heterogeneity, mechanical anisotropy, and adaptability to changing internal and external constraints. Our study focused on adaptive spatiotemporal changes in morphology, anatomy, and mechanical properties during the ontogeny ofL. (Lamiaceae) internodes, proving considerable functional adaptability. Read More

    Evolution and development of monocot stomata.
    Am J Bot 2017 Aug 9. Epub 2017 Aug 9.
    Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
    Premise Of The Study: Leaves of monocots are typically linear with parallel venation, though a few taxa have broad leaves. Studies of stomatal patterning and development in monocots required updating in the context of rapidly improving knowledge of both the phylogenetic and development-genetic context of monocots that facilitate studies of character evolution.

    Methods: We used an existing microscope-slide collection to obtain data on stomatal structure across all the major monocot clades, including some species with relatively broad leaves. Read More

    Floristic response to urbanization: Filtering of the bioregional flora in Indianapolis, Indiana, USA.
    Am J Bot 2017 Aug 9. Epub 2017 Aug 9.
    The Morton Arboretum, Lisle, Illinois 60523.
    Premise Of The Study: Globally, urban plant populations are becoming increasingly important, as these plants play a vital role in ameliorating effects of ecosystem disturbance and climate change. Urban environments act as filters to bioregional flora, presenting survival challenges to spontaneous plants. Yet, because of the paucity of inventory data on plants in landscapes both before and after urbanization, few studies have directly investigated this effect of urbanization. Read More

    Learning in two butterfly species when using flowers of the tropical milkweed: No benefits for pollination.
    Am J Bot 2017 Aug 8. Epub 2017 Aug 8.
    Laboratório de Interações Inseto-Planta, Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, P.O. Box 68020, 21.941-902 Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
    Premise Of The Study: The ability of insect visitors to learn to manipulate complex flowers has important consequences for foraging efficiency and plant fitness. We investigated learning by two butterfly species,and, as they foraged on the complex flowers of, as well as the consequences for pollination.

    Methods: To examine learning with respect to flower manipulation, butterflies were individually tested during four consecutive days under insectary conditions. Read More

    Transitions from distyly to homostyly are associated with floral evolution in the buckwheat genus ().
    Am J Bot 2017 Aug 8. Epub 2017 Aug 8.
    School of Life Sciences, Central China Normal University, Wuhan 430079, China
    Premise Of The Study: Documenting trait transitions among species with dimorphic flowers can help to test whether similar patterns of selection are responsible for divergence in floral traits among different species. Heterostyly is thought to promote outcrossing. Theory suggests that the evolutionary transition from heterostylous to homostylous flowers should be accompanied by a reduction in floral size in which pollen size and style length are expected to covary. Read More

    Karyological patterns in the European endemic genusL.: Absolute genome size variation uncorrelated with cytotype chromosome numbers.
    Am J Bot 2017 Aug 8. Epub 2017 Aug 8.
    Plant Science and Biodiversity Centre, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic
    Premise Of The Study: Detailed knowledge about the karyological diversity of organisms undoubtedly represents one of the crucial steps toward a better understanding of their evolutionary trends and history. We investigated the cytotype and absolute genome size (AGS) patterns in the European mountain-dwelling genus(Primulaceae) in light of its geographic distribution and ecological diversification.

    Methods: Our chromosome number survey was based on 34 newly determined and 125 previously published chromosome counts. Read More

    Divergent evolution and niche differentiation within the common peatmoss.
    Am J Bot 2017 Jul 28. Epub 2017 Jul 28.
    NTNU University Museum, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Premise Of The Study: Populations with phenotypic polymorphism in discrete characters may be good models for investigating genome evolution and speciation.Brid. is found throughout the northern hemisphere, and despite considerable variation in morphological characters, it is considered one of the least taxonomically controversial peatmoss species. Read More

    Intraspecific life history variation in contrasting habitats: Insights from an obligate symbiotic organism.
    Am J Bot 2017 Jul 28. Epub 2017 Jul 28.
    Rey Juan Carlos University, Biodiversity and Conservation Area, E-28933 Móstoles, Madrid, Spain.
    Premise Of The Study: Life history theory predicts that plants in unfavorable habitats for juvenile growth and survival will commence reproduction at smaller sizes and exhibit higher reproductive allocations than those in favorable habitats. The scope of life history theory will increase if these predictions apply to a broad range of organisms. Populations of organisms in contrasting habitats may experience different demographic rates. Read More

    Plastome sequences of an ancient fern lineage reveal remarkable changes in gene content and architecture.
    Am J Bot 2017 Jul 28. Epub 2017 Jul 28.
    Lewis B. and Dorothy Cullman Program for Molecular Systematics, The New York Botanical Garden, Bronx, New York 10458, USA.
    Premise Of The Study: Comparative analyses of plastid genomes have suggested that gene order and content are relatively stable across the main groups of land plants, with significant changes rarely reported. We examine plastome organization and RNA editing in ferns and report changes that add valuable information on plastome evolution in land plants.

    Methods: Using next-generation sequencing methods, we fully sequenced plastomes from three species of Schizaeaceae, and compared their plastomes with other groups of land plants to study changes in gene composition, plastome architecture, and putative RNA editing sites. Read More

    First discovery of the charophycean green alga(Charophyceae) extant in the New World.
    Am J Bot 2017 Jul 27. Epub 2017 Jul 27.
    Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103 USA.
    Premise Of The Study: Although some species of Characeae, known as stoneworts, can be found on every continent except Antarctica, many species and some genera have limited geographic distributions. The genus, represented by a single extant species, was known only from scattered localities in Europe and Australasia until it was recently discovered in North America.

    Methods: Morphological identifications were made from specimens collected in Minnesota and Wisconsin, USA. Read More

    High growth temperatures and high soil nitrogen do not alter differences in COassimilation between invasive(reed canarygrass) and(tussock sedge).
    Am J Bot 2017 Jul 25. Epub 2017 Jul 25.
    Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409 USA
    Premise Of The Study: Global change in temperature and soil nitrogen availability could affect plant community composition, potentially giving an advantage to invasive species compared to native species. We addressed how high temperatures affected COassimilation parameters for invasiveand a sedge,, it displaces, in natural and controlled environments.

    Methods: Photosynthetic parameters were measured in a wetland in Indiana, USA during the abnormally warm year of 2012. Read More

    Anatolian origins and diversification of, the sister lineage of the core Brassicaceae.
    Am J Bot 2017 Jul 25. Epub 2017 Jul 25.
    Biosystematics, Plant Science Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
    Premise Of The Study: The Irano-Turanian region harbors three biodiversity hotspots and ∼25% of Brassicaceae species are endemic to the region.(∼61 species) is the sister lineage to the core Brassicaceae and occurs mainly in the Irano-Turanian region. The evolutionary important position ofmakes it an ideal reference for broader comparative genetics and genomics. Read More

    Less is more: Independent loss-of-functionalleles parallel pollination syndrome diversification in monkeyflowers ().
    Am J Bot 2017 Jul 19. Epub 2017 Jul 19.
    Department of Biology, Box 351800, University of Washington, Seattle, Washington 98195 USA
    Premise Of The Study: Pollinator-mediated selection on flower phenotypes (e.g., shape, color, scent) is key to understanding the adaptive radiation of angiosperms, many of which have evolved specialized relationships with a particular guild of animal pollinators (e. Read More

    Vascular development in very young conifer seedlings: Theoretical hydraulic capacities and potential resistance to embolism.
    Am J Bot 2017 Jul 19. Epub 2017 Jul 19.
    875 Perimeter Drive MS 1133, College of Natural Resources, University of Idaho, Moscow, Idaho 83844 USA.
    Premise Of The Study: Conifers have the highest rates of mortality during their first year, often attributed to water stress; yet, this tree life stage is the least studied in terms of hydraulic properties. Previous work has revealed correlations between xylem anatomy to both hydraulic transport capacity and resistance to hydraulic dysfunction. In this study, we compared xylem anatomical and plant functional traits of,, andseedlings over the first 10 wk of growth to evaluate potential maximum hydraulic capabilities and resistance to drought-induced embolism. Read More

    Evidence for environment-dependent introgression of adaptive genes between two red oak species with different drought adaptations.
    Am J Bot 2017 Jul 19. Epub 2017 Jul 19.
    School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan 49931-1295 USA
    Premise Of The Study: Introgression of adaptive alleles between hybridizing species is likely an important mechanism to generate new genetic variation for adaptation to rapidly changing environmental conditions. Oaks provide a model for the study of adaptive gene introgression because environmental selection maintains high interspecific differentiation at a few outlier loci and species-specific adaptations despite recurrent interspecific gene flow. Previously, we identified a-like gene under strong divergent selection between drought-tolerantand drought-averse. Read More

    Floral evolution and phylogeny of the Dialioideae, a diverse subfamily of tropical legumes.
    Am J Bot 2017 Jul 14;104(7):1019-1041. Epub 2017 Jul 14.
    Institut de Recherche en Biologie Végétale and Département de Sciences Biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada.
    Premise Of The Study: The Dialioideae is an early diverging clade of caesalpinioid legumes containing approximately 85 species in 17 genera. Dialioideae floral morphology is highly variable and may provide clues to caesalpinioid evolution, but a well-resolved phylogeny is needed. Here, we have carried out a comprehensive morphological study of 78 Dialioideae and four outgroup species. Read More

    Incomplete lineage sorting and hybridization in the evolutionary history of closely related, endemic yellow-floweredspecies of subgenus(Bromeliaceae).
    Am J Bot 2017 Jul 14;104(7):1073-1087. Epub 2017 Jul 14.
    Universidade Federal do Rio Grande do Sul, Instituto de Biociências, Programa de Pós-graduação em Genética e Biologia Molecular, Avenida Bento Gonçalves 9500, P.O. Box 15053 91501-970, Porto Alegre, RS, Brazil
    Premise Of The Study: The yellow-floweredsubgenus(yfAsO) (Bromeliaceae) is a group of seven morphologically similar bromeliads found mostly in the southern Brazilian Atlantic rainforest. The recent origin of this group probably contributes to its taxonomic complexity. The aims of this study were to investigate the levels of genetic diversity and structure at the population and species levels, to gain insight into the processes behind the diversification of the group, and to contribute to the establishment of species boundaries. Read More

    Visualization of extracellular DNA released during border cell separation from the root cap.
    Am J Bot 2017 Jul 14;104(7):970-978. Epub 2017 Jul 14.
    Department of Soil, Water and Environmental Science, 429 Shantz Building #38, The University of Arizona, Tucson, Arizona 85721, USA
    Premise Of The Study: Root border cells are programmed to separate from the root cap as it penetrates the soil environment, where the cells actively secrete >100 extracellular proteins into the surrounding mucilage. The detached cells function in defense of the root tip by an extracellular trapping process that also requires DNA, as in mammalian white blood cells. Trapping in animals and plants is reversed by treatment with DNase, which results in increased infection. Read More

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