Plant Breeding and Genetics Commons^™

Production Of Black And Navy Beans In Virginia, Harbans L. Bhardwaj, Satya S. S. Narina Ph.D.

Virginia Journal of Science

An urgent need exists in Virginia and adjoining states to identify crops to replace declining tobacco acreage. Although not traditionally grown in the region, dry beans (Phaseolus vulgaris L.) have considerable potential as alternative summer crops due to their nutritional benefits and increasing consumer demand. Information on the production potential of these crops in Virginia, however, is not yet available. To remedy this situation, replicated field trials were conducted over three years with six black and four navy bean varieties to characterize grain yields following three row spacings and three planting times. Black beans significantly out-yielded navy beans (2095 …

Characterization Of Pigeonpea As An Alternate Summer Forage Crop In Virginia, Satya S. S. Narina, Glenn Chappell Iii, Harbans L. Bhardwaj

Virginia Journal of Science

Pigeonpea (Cajanus cajan L.), a major multifunctional food legume crop valued globally, contributes to food security by supplying protein-rich grain for human consumption and provides nutrient-rich biomass for livestock feeding across diverse production systems. However, little is known about its forage potential in the mid-Atlantic region of the United States. In 2009 and 2010, four cultivars (GA-1, GA-2, W-1, and W-3) were evaluated in a split-plot design with three intra-row plant populations (2, 4, or 6 plants per 0.3 m row) and three planting dates (May, June, and July). Forage yield, crude protein, minerals, and other nutritional traits were …

Divergent Floral And Vegetative Trait Responses To Abiotic Factors Drive Phenotypic Diversity In Platanthera Dilatata (Orchidaceae) Across Alaska, Marlin L. Bowles, Lisa E. Wallace

Biological Sciences Faculty Publications

Multiple traits make up an integrated phenotype, but traits may be shaped by differing drivers. It is often assumed that selection by biotic agents drives floral variation, but abiotic factors are also known to influence floral traits. Understanding trait covariations and their association with diverse environmental factors is a central question in evolution and ecology. Here, we studied covariation in floral and vegetative traits in relation to climate and topo-edaphic variation in the orchid Platanthera dilatata. In Platanthera, nectar spur length is associated with pollinator tongue length, but much variation exists in other traits too, likely to be …

Floral And Genetic Divergence Across Environmental Gradients Is Moderated By Inter-Population Gene Flow In Platanthera Dilatata (Orchidaceae), Lisa E. Wallace, Marlin L. Bowles

Biological Sciences Faculty Publications

Understanding how natural selection acts on intraspecific variation to bring about phenotypic divergence is critical to understanding processes of evolutionary diversification. The orchid family is well known for pollinator-mediated selection of floral phenotypes operating among species and along environmental or geographic gradients. Its effectiveness at small spatial scales is less understood, making the geographic scale at which intraspecific floral variation is examined important to evaluating causes of phenotypic divergence. In this study, we quantified phenotypic variation in the orchid Platanthera dilatata across 26 populations in coastal Southeast Alaska and compared this to edaphic and genetic variation at microsatellite loci. We …

Determinants Of Population Genetic Structure In Chamaecrista Fasciculata (Michx.) Greene (Fabaceae) In The Southeastern United States, Mahboubeh Hosseinalizadeh Nobarinezhad, Lisa E. Wallace

Biological Sciences Faculty Publications

Chamaecrista fasciculata is a widely distributed, phenotypically variable species in the eastern U.S. Whereas studies have demonstrated genetic structure and local adaptation in northern areas of its distribution, there has been no comparison of genetic variability among populations at the southern extent where phenotypic variation is more complex. We characterized genetic variation at 14 microsatellite loci for populations in Mississippi and Alabama and compared this to variation in a phenotypic trait, leaf pubescence. Geographic distance, climatic variables, and elevation were evaluated as factors to explain the observed patterns of genetic diversity. A significant amount of variation (19%) resided among populations, …

The Challenges Of Growing Orchids From Seeds For Conservation: An Assessment Of Asymbiotic Techniques, Devani Jolman, Martín I. Batalla, Alexis Hungerford, Pryce Norwood, Noah Tait, Lisa E. Wallace

Biological Sciences Faculty Publications

Lewis Knudson first successfully germinated orchid seeds asymbiotically on artificial medium in 1922. While many orchid species have since been grown asymbiotically, the tremendous variation in how species respond to artificial medium and growth conditions ex situ has also become apparent in the past century. In this study, we reviewed published journal articles on asymbiotic orchid seed germination to provide a summary of techniques used and to evaluate if these differ between terrestrial and epiphytic species, to identify areas where additional research is needed, and to evaluate whether asymbiotic germination could be used more often in ex situ conservation. We …

Patterns Of Genetic Divergence Across Geographically Variable Populations Of Xanthisma Gracile (Asteraceae), Lavanya Challagundla, Lisa E. Wallace

Biological Sciences Faculty Publications

Premise of research. Numerous biotic and abiotic factors can contribute to local selection and lead to geographic structure and genetic divergence between populations. The southwestern United States contains many distinctive plant communities, ranging from woodlands to desert scrub, that are shaped by species adapting to local variation in elevation, precipitation, seasonality, and soils. Given this variation, species occurring across diverse habitats are expected to harbor high genetic diversity and exhibit significant genetic differences associated with environmental variation.

Methodology. Here, we studied the genetic divergence of populations of Xanthisma gracile (Asteraceae) across Arizona using amplified fragment length polymorphisms and evaluated associations …

Fine-Scale Patterns Of Genetic Structure In The Host Plant Chamaecrista Fasciculata (Fabaceae) And Its Nodulating Rhizobia Symbionts, Mahboubeh Hosseinalizadeh Nobarinezhad, Lisa A. Wallace

Biological Sciences Faculty Publications

In natural plant populations, a fine-scale spatial genetic structure (SGS) can result from limited gene flow, selection pressures or spatial autocorrelation. However, limited gene flow is considered the predominant determinant in the establishment of SGS. With limited dispersal ability of bacterial cells in soil and host influence on their variety and abundance, spatial autocorrelation of bacterial communities associated with plants is expected. For this study, we collected genetic data from legume host plants, Chamaecrista fasciculata, their Bradyrhizobium symbionts and rhizosphere free-living bacteria at a small spatial scale to evaluate the extent to which symbiotic partners will have similar SGS …

Patterns Of Genetic Diversity In Highly Invasive Species: Cogongrass (Imperata Cylindrica) Expansion In The Invaded Range Of The Southern United States (Us), Rima D. Lucardi, Lisa E. Wallace, Gary N. Ervin

Biological Sciences Faculty Publications

The spatial expansions of invasive organisms in the novel range are generally expected to follow an isolation-by-distance relationship (IBD) if the invasion is biologically driven; however, many invasions are facilitated anthropogenically. This research focused on the extant expansion patterns of cogongrass (Imperata cylindrica). Cogongrass is a widespread invasive species throughout the southern United States (US). Patterns of infestation vary among US states. Cogongrass is pyrogenic, and its invasion threatens softwood (Pinus spp.) plantations, a substantial economic market for this US region. Over 600 individuals were sampled from seven invaded US states, using amplified fragment length polymorphisms (AFLPs) …

Molecular Systematics Of Isoëtes (Isoëtaceae) In Eastern North America, Peter William Schafran

Biological Sciences Theses & Dissertations

Isoëtes (Isoëtaceae, Isoetales, Lycopodiophyta) is a cosmopolitan genus of aquatic lycophytes, occurring on every continent except Antarctica. Of approximately 200 total taxa, about half are in a clade of species mostly occurring in North and South America. Eastern North America accounts for 22% of global taxonomic diversity, containing 32 fertile taxa and 16 named hybrids. This taxonomic diversity is built upon relatively little morphological difference, and even combined with phylogenetic analysis using several nuclear and chloroplast DNA markers, no well-resolved systematic treatment within this clade exists.

This study aims to clarify the relationships between all species and subspecies of Isoëtes …

Diversity Of Nitrogen-Fixing Symbionts Of Chamaecrista Fasciculata (Partridge Pea) Across Variable Soils, Hanna E. Dorman, Lisa E. Wallace

Biological Sciences Faculty Publications

We evaluated whether geographic distance and soil characteristics influence genetic structure of nitrogen-fixing bacterial symbionts associated with the host plant Chamaecrista fasciculata (Partridge Pea). We tested phylogeographic clustering and associations between genetic distance, geographic distance, and soil variables using sequences of 2 bacterial genes and soil chemistry across 23 sites in Mississippi. We identified rhizobia isolated from Partridge Pea as Bradyrhizobium. We detected significant genetic structure at a regional level, and determined that rhizobia within each region were more phylogenetically related than expected. Significant correlation between genetic distance and distances based on soil chemistry suggests environmental influences on rhizobia …

Low- Copy Nuclear Markers In Isoëtes (Isoëtaceae) Identified With Transcriptomes, Peter W. Schafran, Gabriel Johnson, W. Carl Taylor, Elizabeth A. Zimmer, Lytton J. Musselman

Biological Sciences Faculty Publications

PREMISE OF THE STUDY: Few genetic markers provide phylogenetic information in closely related species of Isoëtes (Isoëtaceae). We describe the development of primers for several putative low- copy nuclear markers to resolve the phylogeny of Isoëtes, particularly in the southeastern United States.

METHODS AND RESULTS: We identified regions of interest in Isoëtes transcriptomes based on low- copy genes in other plants. Primers were designed for these regions and tested with 16 taxa of Isoëtes and one species of Lycopodium. Parts of the pgiC, gapC, and IBR3 gene regions show phylogenetic signal within the North American and …

Molecular Phylogenetics Of Alternanthera (Gomphrenoideae, Amaranthaceae): Resolving A Complex Taxonomic History Caused By Different Interpretations Of Morphological Characters In A Lineage With C4 And C3-C4 Intermediate Species, Ivonne Sánchez-Del Pino, Timothy J. Motley, Thomas Borsch

Biological Sciences Faculty Publications

Aternanthera (Amaranthaceae) is a diverse genus (80-200 species) largely restricted to the American Tropics. With Pedersenia and Tidestromia, it makes up the Alternantheroid clade in Gomphrenoideae. Parsimony and Bayesian analyses of nucleotide sequences of nuclear (ITS) and plastid (rpl16, trnL-F) and morphological characters identify that the capitate stigma of Alternanthera is a synapomorpy within the Alternantheroids. Within Alternanthera, two major clades were resolved, both of which were marked by otherwise homoplasious characters of the gynoecium: Clade A [99% jackknife (JK); 1.0 posterior probability (PP)] with nine species and Clade B (60% JK; 0.98 PP) with 22 …

Anther Appendages Of Incarvillea Trigger A Pollen-Dispensing Mechanism, Yi Han, Can Dai, Chun-Feng Yang, Qing-Feng Wang, Timothy J. Motley

Biological Sciences Faculty Publications

Background and Aims Anther appendages play diverse roles in anther dehiscence and pollen dispersal. This study aims to explore the pollen-dispensing mechanism triggered by special anther appendages in Incarvillea arguta.

Methods Field studies were conducted to record floral characteristics, pollinator visitations, and flower-pollinator interactions. Measurements of flowers and pollinators were analysed statistically. Pollen counts following a series of floral manipulations were used to evaluate pollen dispensing efficiency and function of the anther appendages.

Key Results Field observations determined that two species of Bombus (bumble-bees) were the primary pollinators of I. arguta with a mean visiting frequency of 1.42 visitations …

An Investigation Of The Nucleotide Cyclic 3'5' Adenosine Monophosphate In Young Hypocotyls Of Pisum Sativum L., Gary Marsh Hilton

Biological Sciences Theses & Dissertations

Concentrations of cAMP increased with time in pea hypocotyls assayed at 24 hour intervals over a period of four days. The highest concentration was 20.1 pmoles/mg protein which occurred in 96 hour hypocotyl tips. Ninety-six hour root bodies (dissected region between tip and embryo) achieved a concentration of 8.6 pmoles/mg. Concentrations of cAMP in embryos remained constant around one pmole/mg for three days and values doubled on the fourth day.

Hypocotyls, after germination for 72 hours, were dissected and incubated for various lengths of time in water and 3xl0^-8M IAA. Tips incubated for two hours showed a tenfold …