5,155 results match your criteria American journal of botany[Journal]


Ontogenetic scaling of phloem sieve tube anatomy and hydraulic resistance with tree height in Quercus rubra.

Am J Bot 2020 May 28. Epub 2020 May 28.

Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA.

Premise: The dimensions of phloem sieve elements have been shown to vary as a function of tree height, decreasing hydraulic resistance as the transport pathway lengthens. However, little is known about ontogenetic patterns of sieve element scaling. Here we examine within a single species (Quercus rubra) how decreases in hydraulic resistance with distance from the plant apex are mediated by overall plant size. Read More

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http://dx.doi.org/10.1002/ajb2.1481DOI Listing

Patterns of variation in distylous traits and reproductive consequences in Erythroxylum species and populations.

Am J Bot 2020 May 28. Epub 2020 May 28.

Biotechnology Institute, Federal University of Catalão, Catalão, Goiás, Brazil.

Premise: Distylous species possess two floral morphs with reciprocal positioning of stigmas and anthers that is hypothesized to promote disassortative pollination. Theoretical models predict equal morph frequencies, but many populations depart from the expected 1:1 ratio, a pattern that often correlates with asymmetric mating between morphs and/or presence of a weak incompatibility system. Variation in reciprocity can also affect the likelihood of disassortative pollination and, hence, reproductive fitness. Read More

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http://dx.doi.org/10.1002/ajb2.1478DOI Listing

Pods as sails but not as boats: dispersal ecology of a habitat-restricted desert milkvetch.

Am J Bot 2020 May 27. Epub 2020 May 27.

USDA Forest Service Rocky Mountain Research Station, Shrub Sciences Laboratory, 735 North 500 East, Provo, UT, 84606, USA.

Premise: Adaptive seed dispersal mechanisms are fundamental to plant fitness, but dispersal advantage is scale-dependent. We tested the hypothesis that informed dispersal in response to an environmental cue enables dispersal by wind on a local scale for Astragalus holmgreniorum, a desert species restricted to swales and wash skirts with overland flow, but prevents longer-distance dispersal by water into unfavorable wash habitats.

Methods: Pod biomechanics in A. Read More

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http://dx.doi.org/10.1002/ajb2.1473DOI Listing

It's all about timing-or is it? Exploring the potential connection between phloem physiology and whole plant phenology.

Authors:
Jessica A Savage

Am J Bot 2020 May 26. Epub 2020 May 26.

University of Minnesota, Duluth, MN, 55812, USA.

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http://dx.doi.org/10.1002/ajb2.1480DOI Listing

A combination of morphological and photosynthetic functional traits maintains the vertical distribution of bryophytes in a subtropical cloud forest.

Am J Bot 2020 May;107(5):761-772

Institute of Medical Biology, Chinese Academy of Medical Sciences, Kunming, Yunnan Province, 650031, China.

Premise: The distribution and performance of bryophyte species vary with vertical gradients, as a result of changes in environmental factors, especially light. However, the morphological and physiological drivers of bryophyte distribution along forest vertical gradients are poorly understood.

Methods: For 18 species of mosses and liverworts distributed among three vertical microhabitats (ground, tree trunk, and branch, variance in 28 morphological and photosynthetic functional traits was comparatively analyzed among the microhabitats and bryophyte life-forms in a subtropical cloud forest in Ailao Mountain, Yunnan, southwestern China. Read More

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http://dx.doi.org/10.1002/ajb2.1474DOI Listing

Is heterospecific pollen receipt the missing link in understanding pollen limitation of plant reproduction?

Am J Bot 2020 May 23. Epub 2020 May 23.

Institute of Biology, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108, Halle (Saale), Germany.

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http://dx.doi.org/10.1002/ajb2.1477DOI Listing

Diversity, distribution, development, and evolution of medullary bundles in Nyctaginaceae.

Am J Bot 2020 May 20;107(5):707-725. Epub 2020 May 20.

Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Cidade Universitária, CEP 05508-090, São Paulo, SP, Brazil.

Premise: Medullary bundles, i.e., vascular units in the pith, have evolved multiple times in vascular plants. Read More

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http://dx.doi.org/10.1002/ajb2.1471DOI Listing

A quick glance at noteworthy articles for May 2020.

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Am J Bot 2020 May 18;107(5):701-702. Epub 2020 May 18.

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http://dx.doi.org/10.1002/ajb2.1476DOI Listing

Seed source regions drive fitness differences in invasive macrophytes.

Am J Bot 2020 May 14;107(5):749-760. Epub 2020 May 14.

USDA-Agricultural Research Service, Invasive Species and Pollinator Health Research Unit, Department of Plant Sciences MS-4, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA.

Premise: Worldwide, ecosystems are threatened by global changes, including biological invasions. Invasive species arriving in novel environments experience new climatic conditions that can affect their successful establishment. Determining the response of functional traits and fitness components of invasive populations from contrasting environments can provide a useful framework to assess species responses to climate change and the variability of these responses among source populations. Read More

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http://dx.doi.org/10.1002/ajb2.1475DOI Listing

Nuclear phylogenomic analyses of asterids conflict with plastome trees and support novel relationships among major lineages.

Am J Bot 2020 May 13;107(5):790-805. Epub 2020 May 13.

Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA.

Premise: Discordance between nuclear and organellar phylogenies (cytonuclear discordance) is a well-documented phenomenon at shallow evolutionary levels but has been poorly investigated at deep levels of plant phylogeny. Determining the extent of cytonuclear discordance across major plant lineages is essential not only for elucidating evolutionary processes, but also for evaluating the currently used framework of plant phylogeny, which is largely based on the plastid genome.

Methods: We present a phylogenomic examination of a major angiosperm clade (Asteridae) based on sequence data from the nuclear, plastid, and mitochondrial genomes as a means of evaluating currently accepted relationships inferred from the plastome and exploring potential sources of genomic conflict in this group. Read More

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http://dx.doi.org/10.1002/ajb2.1468DOI Listing

Leaf margins in a deciduous lineage from the Greater Cape Floristic Region track climate in unexpected directions.

Am J Bot 2020 May 12;107(5):735-748. Epub 2020 May 12.

Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.

Premise: The functional significance of leaf margins has long been debated. In this study, we explore influences of climate, leaf lobing, woodiness, and shared evolutionary history on two leaf margin traits within the genus Pelargonium.

Methods: Leaves from 454 populations of Pelargonium (161 species) were collected in the Greater Cape Floristic Region and scored for tooth presence/absence and degree of lobing. Read More

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http://dx.doi.org/10.1002/ajb2.1472DOI Listing

Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America.

Am J Bot 2020 May 9;107(5):806-832. Epub 2020 May 9.

Museo Paleontológico Egidio Feruglio, Consejo Nacional de Investigaciones Científicas y Técnicas, Trelew, 9100, Chubut, Argentina.

Premise: Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Read More

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http://dx.doi.org/10.1002/ajb2.1467DOI Listing

A consensus phylogenomic approach highlights paleopolyploid and rapid radiation in the history of Ericales.

Am J Bot 2020 May 29;107(5):773-789. Epub 2020 Apr 29.

Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.

Premise: Large genomic data sets offer the promise of resolving historically recalcitrant species relationships. However, different methodologies can yield conflicting results, especially when clades have experienced ancient, rapid diversification. Here, we analyzed the ancient radiation of Ericales and explored sources of uncertainty related to species tree inference, conflicting gene tree signal, and the inferred placement of gene and genome duplications. Read More

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http://dx.doi.org/10.1002/ajb2.1469DOI Listing

Bark water storage capacity influences epiphytic orchid preference for host trees.

Am J Bot 2020 May 28;107(5):726-734. Epub 2020 Apr 28.

CONACYT Research Fellow-Colegio de Postgraduados Campus Campeche, Carretera Haltunchen-Edzná km 17.5, Sihochac, 24450, Municipio de Champotón, Campeche, México.

Premise: Of all orchid species described, 70% live on phorophytes. Trees offer a vital space with characteristics that influence the successful establishment and life cycle of orchids. Field inventory and distribution analysis suggest that phorophyte selection is biased to certain tree species that would serve as better hosts. Read More

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http://dx.doi.org/10.1002/ajb2.1470DOI Listing

Whole genome duplication does not promote common modes of reproductive isolation in Trifolium pratense.

Am J Bot 2020 May 23;107(5):833-841. Epub 2020 Apr 23.

Syracuse University, Biology, 107 College Place, Syracuse, New York, 13244, USA.

Premise: Although polyploidy has been studied since the early 1900s, fundamental aspects of polyploid ecology and evolution remain unexplored. In particular, surprisingly little is known about how newly formed polyploids (neopolyploids) become demographically established. Models predict that most polyploids should go extinct within the first few generations as a result of reproductive disadvantages associated with being the minority in a primarily diploid population (i. Read More

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http://dx.doi.org/10.1002/ajb2.1466DOI Listing

A quick glance at noteworthy articles for April 2020.

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Am J Bot 2020 Apr;107(4):539-540

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http://dx.doi.org/10.1002/ajb2.1464DOI Listing

The role of auxin in developmentally regulated programmed cell death in lace plant.

Am J Bot 2020 04 21;107(4):577-586. Epub 2020 Apr 21.

Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS, B3H 4R2, Canada.

Premise: Lace plant (Aponogeton madagascariensis) leaves are remodeled via developmental programmed cell death (PCD) to produce perforations located equidistantly between longitudinal and transverse veins. Auxin has been implicated in other developmental PCD processes in plants; however, the role of auxin in perforation formation in lace plant is unknown. Here the role of auxin in developmental PCD in lace plant was studied using two auxin inhibitors N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, and auxinole, a potent auxin antagonist. Read More

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http://dx.doi.org/10.1002/ajb2.1463DOI Listing

Evidence for newly discovered albino mutants in a pyroloid: implication for the nutritional mode in the genus Pyrola.

Am J Bot 2020 04 17;107(4):650-657. Epub 2020 Apr 17.

Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, Hyogo, 657-8501, Japan.

Premise: Difficulties in comparing extremely divergent features in fully mycoheterotrophic plants with those in closely related chlorophyllous plants have complicated attempts to reveal the evolutionary patterns and processes of fully mycoheterotrophic plants. Albino mutants of partially mycoheterotrophic plants, generally observed in Orchidaceae, have provided an ideal model for investigating the evolution of mycoheterotrophy within similar genetic backgrounds. In 2018, we found a putative albino population of Pyrola (Ericaceae). Read More

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http://dx.doi.org/10.1002/ajb2.1462DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216931PMC

Is biodiversity needed for sustainability? A spotlight on urban landscapes.

Authors:
Jocelyn E Behm

Am J Bot 2020 May 17;107(5):703-706. Epub 2020 Apr 17.

Integrative Ecology Lab, Center for Biodiversity, Department of Biology, Temple University, 1925 N. 12th Street, Philadelphia, PA, 19122, USA.

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http://dx.doi.org/10.1002/ajb2.1465DOI Listing

The influences of environmental change and development on leaf shape in Vitis.

Am J Bot 2020 04 9;107(4):676-688. Epub 2020 Apr 9.

Terrestrial Paleoclimate Research Group, Department of Geosciences, Baylor University, Waco, TX, USA.

Premise: The size and shape (physiognomy) of woody, dicotyledonous angiosperm leaves are correlated with climate. These relationships are the basis for multiple paleoclimate proxies. Here we test whether Vitis exhibits phenotypic plasticity and whether physiognomy varies along the vine. Read More

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http://dx.doi.org/10.1002/ajb2.1460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217169PMC

Infraspecific diversification of the star cloak fern (Notholaena standleyi) in the deserts of the United States and Mexico.

Am J Bot 2020 04 7;107(4):658-675. Epub 2020 Apr 7.

Department of Biology, Duke University, Durham, North Carolina, 27708, USA.

Premise: Not all ferns grow in moist and shaded habitats. One well-known example is Notholaena standleyi, a species that thrives in deserts of the southwestern United States and Mexico. This species exhibits several "chemotypes" that differ in farina (flavonoid exudates) color and chemistry. Read More

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http://dx.doi.org/10.1002/ajb2.1461DOI Listing

Some (do not) like it hot: shrub growth is hampered by heat and drought at the alpine treeline in recent decades.

Am J Bot 2020 04 1;107(4):607-617. Epub 2020 Apr 1.

Climate Change Impacts and Risks in the Anthropocene (C-CIA), Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland.

Premise: Mountain ecosystems are particularly sensitive to climate change. However, only a very small number of studies exist so far using annually resolved records of alpine plant growth spanning the past century. Here we aimed to identify the effects of heat waves and drought, driven by global warming, on annual radial growth of Rhododendron ferrugineum. Read More

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http://dx.doi.org/10.1002/ajb2.1459DOI Listing

Relationships between population traits, nonstructural carbohydrates, and elevation in alpine stands of Vaccinium myrtillus.

Am J Bot 2020 04 1;107(4):639-649. Epub 2020 Apr 1.

Department of Agriculture, Food, Environmental and Animal Sciences, Plant Biology Unit, University of Udine, via delle Scienze 91, 33100, Udine, Italy.

Premise: Despite great attention given to the relationship between plant growth and carbon balance in alpine tree species, little is known about shrubs at the treeline. We hypothesized that the pattern of main nonstructural carbohydrates (NSCs) across elevations depends on the interplay between phenotypic trait plasticity, plant-plant interaction, and elevation.

Methods: We studied the pattern of NSCs (i. Read More

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http://dx.doi.org/10.1002/ajb2.1458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217170PMC

Trait integration and functional differentiation among co-existing plant species.

Am J Bot 2020 04 1;107(4):628-638. Epub 2020 Apr 1.

Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR, 97331, USA.

Premise: Determining which traits characterize strategies of coexisting species is important to developing trait-based models of plant communities. First, global dimensions may not exist locally. Second, the degree to which traits and trait spectra constitute independent dimensions of functional variation at various scales continues to be refined. Read More

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http://dx.doi.org/10.1002/ajb2.1451DOI Listing

Factors controlling drought resistance in grapevine (Vitis vinifera, chardonnay): application of a new microCT method to assess functional embolism resistance.

Am J Bot 2020 04 31;107(4):618-627. Epub 2020 Mar 31.

Department of Biology, California State University-Bakersfield, Bakersfield, CA, 93311, USA.

Premise: Quantifying resistance to embolism in woody plants is important for understanding their drought response. Methods to accurately quantify resistance to embolism continue to be debated.

Methods: We used a new microCT-based approach that quantifies embolized conduits and also analyzes conductive conduits by using an x-ray-dense, iodine-rich tracer that moves though the vascular system and can easily be observed in microCT images. Read More

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http://dx.doi.org/10.1002/ajb2.1450DOI Listing

Gigantic chloroplasts, including bizonoplasts, are common in shade-adapted species of the ancient vascular plant family Selaginellaceae.

Am J Bot 2020 04 29;107(4):562-576. Epub 2020 Mar 29.

Department of Life Sciences & Research Center for Global Change Biology, National Chung Hsing University, Taichung, Taiwan.

Premise: Unique among vascular plants, some species of Selaginella have single giant chloroplasts in their epidermal or upper mesophyll cells (monoplastidy, M), varying in structure between species. Structural variants include several forms of bizonoplast with unique dimorphic ultrastructure. Better understanding of these structural variants, their prevalence, environmental correlates and phylogenetic association, has the potential to shed new light on chloroplast biology unavailable from any other plant group. Read More

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http://dx.doi.org/10.1002/ajb2.1455DOI Listing

Influence of local density and sex ratio on pollination in an ambophilous flowering plant.

Am J Bot 2020 04 30;107(4):587-598. Epub 2020 Mar 30.

Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada.

Premise: Variation in local density and sex ratio in dioecious plants can affect mating success through the actions of pollen vectors, principally generalist insects or wind. Increased density and male-biased sex ratios should promote pollen transfer and seed production, but their combined effects have not been investigated for ambophilous species, which exhibit both insect and wind pollination.

Methods: We manipulated density (low vs. Read More

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http://dx.doi.org/10.1002/ajb2.1453DOI Listing

The invasive plant Solidago canadensis exhibits partial local adaptation to low salinity at germination but not at later life-history stages.

Am J Bot 2020 04 30;107(4):599-606. Epub 2020 Mar 30.

Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, 318000, China.

Premise: Evolutionary adaptation may enable plants to inhabit a broad range of environments. However, germination and early life-history stages have seldom been considered in estimates of evolutionary adaptation. Moreover, whether soil microbial communities can influence evolutionary adaptation in plants remains little explored. Read More

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http://dx.doi.org/10.1002/ajb2.1456DOI Listing

The anatomy of abscission zones is diverse among grass species.

Am J Bot 2020 04 23;107(4):549-561. Epub 2020 Mar 23.

Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO, 62132, USA.

Premise: Abscission zones (AZ) are specialized cell layers that separate plant parts at the organ junction upon developmental or environmental signals. Fruit or seed abscission has been well studied in model species because of its crucial role for seed dispersal. Previous work showed that AZ localization differs among species of Poaceae and that AZ formation is histologically and genetically distinct in three distantly related grass species, refuting the idea of a broadly conserved module. Read More

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http://dx.doi.org/10.1002/ajb2.1454DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217018PMC

Population genomics of the widespread African savannah trees Afzelia africana and Afzelia quanzensis reveals no significant past fragmentation of their distribution ranges.

Am J Bot 2020 03;107(3):498-509

Evolutionary Biology and Ecology Unit, CP 160/12, Faculté des Sciences, Université Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050, Brussels, Belgium.

Premise: Few studies have addressed the evolutionary history of tree species from African savannahs. Afzelia contains economically important timber species, including two species widely distributed in African savannahs: A. africana in the Sudanian region and A. Read More

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http://dx.doi.org/10.1002/ajb2.1449DOI Listing

Reticulate evolution, lateral gene transfer, and innovation in plants.

Am J Bot 2020 04 20;107(4):541-544. Epub 2020 Mar 20.

Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.

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http://dx.doi.org/10.1002/ajb2.1452DOI Listing

Localized defense induction in trees: a mosaic of leaf traits promoting variation in plant traits, predation, and communities of canopy arthropods?

Am J Bot 2020 04 18;107(4):545-548. Epub 2020 Mar 18.

German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.

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http://dx.doi.org/10.1002/ajb2.1457DOI Listing

Reproductive ecology and postpollination development in the hydrophilous monocot Ruppia maritima.

Am J Bot 2020 04 13;107(4):689-699. Epub 2020 Mar 13.

Department of Biology, Creighton University, Omaha, Nebraska, 68178, USA.

Premise: Water-pollination (hydrophily) is a rare but important pollination mechanism that has allowed angiosperms to colonize marine and aquatic habitats. Hydrophilous plants face unique reproductive challenges, and many have evolved characteristic pollen traits and pollination strategies that may have downstream consequences for pollen performance. However, little is known about reproductive development in the life history stage between pollination and fertilization (the progamic phase) in hydrophilous plants. Read More

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http://dx.doi.org/10.1002/ajb2.1447DOI Listing

A quick glance at noteworthy articles for March 2020.

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Am J Bot 2020 03 11;107(3):383-384. Epub 2020 Mar 11.

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http://dx.doi.org/10.1002/ajb2.1446DOI Listing

Plasticity in selective embryo abortion may limit the mating costs of geitonogamy in self-compatible plants: a hypothesis.

Am J Bot 2020 03 10;107(3):390-393. Epub 2020 Mar 10.

Center for Terrestrial Biodiversity of the South China Sea, College of Ecology and Environment, Hainan University, Haikou, 570228, China.

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http://dx.doi.org/10.1002/ajb2.1448DOI Listing

Parallel evolution of arborescent carrots (Daucus) in Macaronesia.

Am J Bot 2020 03 8;107(3):394-412. Epub 2020 Mar 8.

Department of Molecular Phylogenetics and Evolution, Institute of Botany, Faculty of Biology, University of Warsaw, Biological and Chemical Research Centre, Żwirki i Wigury 101, 02-089, Warsaw, Poland.

Premise: Despite intensive research, the pathways and driving forces behind the evolution of derived woodiness on oceanic islands remain obscure. The genus Daucus comprises mostly herbs (therophytes, hemicryptophytes) with few rosette treelets (chamaephytes) endemic to various Macaronesian archipelagos, suggesting their independent evolution. To elucidate the evolutionary pathways to derived woodiness, we examined phylogenetic relationships and the habit and secondary xylem evolution in Daucus and related taxa. Read More

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http://dx.doi.org/10.1002/ajb2.1444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7155066PMC

Is selfing a reproductive assurance promoting polyploid establishment? Reduced fitness, leaky self-incompatibility and lower inbreeding depression in neotetraploids.

Am J Bot 2020 03 6;107(3):526-538. Epub 2020 Mar 6.

Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.

Premise: Newly formed polyploids face significant obstacles to persistence and population establishment because of fitness costs of intercytotype mating. Selfing provides the opportunity to escape mate limitation, enabling production of new individuals and increasing the likelihood of fixation of new polyploid lineages. Still, association between self-compatibility and polyploidy is not always clear. Read More

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http://dx.doi.org/10.1002/ajb2.1441DOI Listing

Life history evolution, species differences, and phenotypic plasticity in hemiparasitic eyebrights (Euphrasia).

Am J Bot 2020 03 4;107(3):456-465. Epub 2020 Mar 4.

University of Edinburgh, Institute of Evolutionary Biology, Charlotte Auerbach Road, Edinburgh, EH9 3FL, UK.

Premise: Species delimitation in parasitic organisms is challenging because traits used to identify species are often plastic and vary depending on the host. Here, we use species from a recent radiation of generalist hemiparasitic Euphrasia to investigate trait variation and trait plasticity. We tested whether Euphrasia species show reliable trait differences, investigated whether these differences correspond to life history trade-offs between growth and reproduction, and quantified plasticity in response to host species. Read More

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http://dx.doi.org/10.1002/ajb2.1445DOI Listing

Genetic relationships and polyploid origins in the Lippia alba complex.

Am J Bot 2020 03 1;107(3):466-476. Epub 2020 Mar 1.

Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, MG, 36036-241, Brazil.

Premise: Plant genomes vary in size and complexity due in part to polyploidization. Latitudinal analyses of polyploidy are biased toward floras of temperate regions, with much less research done in the tropics. Lippia alba has been described as a tropical polyploid complex with diploid, triploid, tetraploid, and hexaploid accessions. Read More

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http://dx.doi.org/10.1002/ajb2.1443DOI Listing

Morphological (and not anatomical or reproductive) features define early vascular plant phylogenetic relationships.

Am J Bot 2020 03 27;107(3):477-488. Epub 2020 Feb 27.

Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York, 14853, USA.

Premise: Perhaps the most rapid period of vascular plant evolution occurred during the Silurian-Devonian time interval. Yet, few quantitative analyses have established the extent to which anatomical, morphological, or reproductive features contributed to this episode of tracheophyte diversification.

Methods: Phylogenetic analyses were performed using a newly revised matrix of 54 characters (with 158 character states) of 37 of the best-preserved Paleozoic (predominantly Devonian) plants. Read More

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http://dx.doi.org/10.1002/ajb2.1440DOI Listing

Cold tolerance in the genus Arabidopsis.

Am J Bot 2020 03 24;107(3):489-497. Epub 2020 Feb 24.

Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, 2140 Koyukuk Drive, P. O. Box 757000, Fairbanks, AK, 99775, USA.

Premise: Cold tolerance is an important factor limiting the geographic distribution and growing season for many plant species, yet few studies have examined variation in cold tolerance extensively within and among closely related species and compared that to their geographic distribution.

Methods: This study examines cold tolerance within and among species in the genus Arabidopsis. We assessed cold tolerance by measuring electrolyte leakage from detached leaves in multiple populations of five Arabidopsis taxa. Read More

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http://dx.doi.org/10.1002/ajb2.1442DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7137905PMC

Fine-scale habitat heterogeneity and vole runways influence seed dispersal in Plagiobothrys nothofulvus.

Am J Bot 2020 03 23;107(3):413-422. Epub 2020 Feb 23.

Department of Biology, Portland State University, P.O. Box 751, Portland, Oregon, 97207, USA.

Premise: Seed dispersal allows plants to colonize new sites and contributes to gene flow among populations. Despite its fundamental importance to ecological and evolutionary processes, our understanding of seed dispersal is limited due to the difficulty of directly observing dispersal events. This is particularly true for the majority of plant species that are considered to have gravity as their primary dispersal mechanism. Read More

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http://dx.doi.org/10.1002/ajb2.1433DOI Listing

Pollinator visitation rate and effectiveness vary with flowering phenology.

Am J Bot 2020 03 21;107(3):445-455. Epub 2020 Feb 21.

Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.

Premise: Flowering time may influence pollination success and seed set through a variety of mechanisms, including seasonal changes in total pollinator visitation or the composition and effectiveness of pollinator visitors.

Methods: We investigated mechanisms by which changes in flowering phenology influence pollination and reproductive success of Mertensia ciliata (Boraginaceae). We manipulated flowering onset of potted plants and assessed the frequency and composition of pollinator visitors, as well as seed set. Read More

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http://dx.doi.org/10.1002/ajb2.1439DOI Listing

When the going gets tough, the tough turn female: injury and sex expression in a sex-changing tree.

Am J Bot 2020 02 21;107(2):339-349. Epub 2020 Feb 21.

Department of Ecology, Evolution & Natural Resources, Rutgers University, New Brunswick, NJ, 08901, USA.

Premise: Plant sex is usually fixed, but in rare cases, sex expression is flexible and may be influenced by environmental factors. Theory links female sex expression to better health, but manipulative work involving the experimental change of health via injury is limited, particularly in sexually plastic species. A better understanding of mechanisms influencing shifts in sex is essential to our understanding of life history theory regarding trade-offs in sex allocation and differential mortality. Read More

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http://dx.doi.org/10.1002/ajb2.1427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7155049PMC
February 2020

Local adaptation mediates floral responses to water limitation in an annual wildflower.

Am J Bot 2020 02 20;107(2):209-218. Epub 2020 Feb 20.

The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA, 02131, USA.

Premise: Understanding how environmental stress affects the strength of mutualisms is critically important given observed and projected environmental changes. In particular, the frequency and duration of drought have been increasing worldwide. We investigated how water availability affects plant traits that mediate a pollination mutualism. Read More

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http://dx.doi.org/10.1002/ajb2.1434DOI Listing
February 2020

Death, sex, and sugars: variations in nonstructural carbohydrate concentrations in a sexually plastic tree.

Am J Bot 2020 02 20;107(2):375-382. Epub 2020 Feb 20.

Department of Ecology, Evolution & Natural Resources, Rutgers University, New Brunswick, NJ, 08901, USA.

Premise: Environmental sex determination (ESD) is a rare sex determination system in which individuals may switch sex expression throughout their lifetimes in response to environmental factors. In sexually stable species, individuals usually bear more female flowers if the plants are larger, have greater access to limiting resources, or are in better condition. Research regarding sexually plastic species with ESD and how resources correlate with sex expression is limited. Read More

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http://dx.doi.org/10.1002/ajb2.1429DOI Listing
February 2020

Phylogeographic and population genetic analyses of Cucurbita moschata reveal divergence of two mitochondrial lineages linked to an elevational gradient.

Am J Bot 2020 03 18;107(3):510-525. Epub 2020 Feb 18.

Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior s/n Anexo al Jardín Botánico, 04510, Ciudad de México, Mexico.

Premise: Domestication usually involves local adaptation to environmental conditions. Cucurbita species are a promising model for studying these processes. Cucurbita moschata is the third major crop in the genus because of its economic value and because it displays high landrace diversity, but research about its genetic diversity, population structure, and phylogeography is limited. Read More

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http://dx.doi.org/10.1002/ajb2.1424DOI Listing

Light availability and rhizobium variation interactively mediate the outcomes of legume-rhizobium symbiosis.

Am J Bot 2020 02 18;107(2):229-238. Epub 2020 Feb 18.

W. K. Kellogg Biological Station and Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.

Premise: Nutrients, light, water, and temperature are key factors limiting the growth of individual plants in nature. Mutualistic interactions between plants and microbes often mediate resource limitation for both partners. In the mutualism between legumes and rhizobia, plants provide rhizobia with carbon in exchange for fixed nitrogen. Read More

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http://dx.doi.org/10.1002/ajb2.1435DOI Listing
February 2020

Variation in morphological traits affects dispersal and seedling emergence in dispersive diaspores of Geropogon hybridus.

Am J Bot 2020 03 18;107(3):436-444. Epub 2020 Feb 18.

Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 8499000, Israel.

Premise: Intraspecific variation in diaspore characteristics could affect various aspects of plant performance at the population, individual plant, and seed levels. We quantified variation in dispersal traits in a wind-dispersed annual, Geropogon hybridus (Asteraceae), focusing on continuous morphological traits of dispersive diaspores and their relationships to dispersal ability and seedling emergence.

Methods: We measured the morphological traits, terminal velocity, and seedling emergence of 1140 seeds from 10 populations in two successive years. Read More

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http://dx.doi.org/10.1002/ajb2.1430DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7154696PMC

Host affinity of endophytic fungi and the potential for reciprocal interactions involving host secondary chemistry.

Am J Bot 2020 02 18;107(2):219-228. Epub 2020 Feb 18.

Smithsonian Tropical Research Institute, Unit 9100 Box 0948, DPO AA 34002-9998, USA.

Premise: Interactions between fungal endophytes and their host plants present useful systems for identifying important factors affecting assembly of host-associated microbiomes. Here we investigated the role of secondary chemistry in mediating host affinity of asymptomatic foliar endophytic fungi using Psychotria spp. and Theobroma cacao (cacao) as hosts. Read More

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http://dx.doi.org/10.1002/ajb2.1436DOI Listing
February 2020