Plant Biology Commons^™

Unprecedented Heterogeneity In The Synonymous Substitution Rate Within A Plant Genome, Andan Zhu, Wenhu Guo, Kanika Jain, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

The synonymous substitution rate varies widely among species, but it is generally quite stable within a genome due to the absence of strong selective pressures. In plants, plastid genes tend to evolve faster than mitochondrial genes, rate variation among species generally correlates between the mitochondrial and plastid genomes, and few examples of intragenomic rate heterogeneity exist. To study the extent of substitution rate variation between and within plant organellar genomes, we sequenced the complete mitochondrial and plastid genomes from the bugleweed, Ajuga reptans, which was previously shown to exhibit rate heterogeneity for several mitochondrial genes. Substitution rates were accelerated specifically …

Evaluation Of Constitutive Iron Reductase (Atfro2) Expression On Mineral Accumulation And Distribution In Soybean (Glycine Max. L), Marta W. Vasconcelos, Thomas E. Clemente, Michael A. Grusak

Center for Plant Science Innovation: Faculty Publications

Iron is an important micronutrient in human and plant nutrition. Adequate iron nutrition during crop production is central for assuring appropriate iron concentrations in the harvestable organs, for human food or animal feed. The whole-plant movement of iron involves several processes, including the reduction of ferric to ferrous iron at several locations throughout the plant, prior to transmembrane trafficking of ferrous iron. In this study, soybean plants that constitutively expressed the AtFRO2 iron reductase gene were analyzed for leaf iron reductase activity, as well as the effect of this transgene's expression on root, leaf, pod wall, and seed mineral concentrations. …

Identification Of Rna Silencing Components In Soybean And Sorghum, Xiang Liu, Tao Lu, Yongchao Dou, Bin Yu, Chi Zhang

Center for Plant Science Innovation: Faculty Publications

Background: RNA silencing is a process triggered by 21–24 small RNAs to repress gene expression. Many organisms including plants use RNA silencing to regulate development and physiology, and to maintain genome stability. Plants possess two classes of small RNAs: microRNAs (miRNAs) and small interfering RNAs (siRNAs). The frameworks of miRNA and siRNA pathways have been established in the model plant, Arabidopsis thaliana (Arabidopsis).

Results: Here we report the identification of putative genes that are required for the generation and function of miRNAs and siRNAs in soybean and sorghum, based on knowledge obtained from Arabidopsis. The gene families, including …

Methylation Protects Micrornas From An Ago1- Associated Activity That Uridylates 5′ Rna Fragments Generated By Ago1 Cleavage, Guodong Ren, Meng Xie, Shuxin Zhang, Carissa Vinovskis, Xuemei Chen, Bin Yu

Center for Plant Science Innovation: Faculty Publications

In plants, methylation catalyzed by HEN1 (small RNA methyl transferase) prevents microRNAs (miRNAs) from degradation triggered by uridylation. Howmethylation antagonizes uridylation of miRNAs in vivo is not well understood. In addition, 5′ RNA fragments (5′ fragments) produced by miRNA-mediated RNA cleavage can be uridylated in plants and animals. However, the biological significance of this modification is unknown, and enzymes uridylating 5′ fragments remain to be identified. Here, we report that in Arabidopsis, HEN1 suppressor 1 (HESO1, a miRNA nucleotidyl transferase) uridylates 5′ fragments to trigger their degradation.We also show that Argonaute 1 (AGO1), the effector protein of miRNAs, interacts …

Small Rnas Meet Their Targets: When Methylation Defends Mirnas From Uridylation, Guodong Ren, Xuemei Chen, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Small RNAs are incorporated into Argonaute protein-containing complexes to guide the silencing of target RNAs in both animals and plants. The abundance of endogenous small RNAs is precisely controlled at multiple levels including transcription, processing and Argonaute loading. In addition to these processes, 3' end modification of small RNAs, the topic of a research area that has rapidly evolved over the last several years, adds another layer of regulation of their abundance, diversity and function. Here, we review our recent understanding of small RNA 3' end methylation and tailing.

Long-Term Changes In Four Plant Communities Along An Elevational Gradient In The Front Range Of Colorado, Gregory J. Sproull

Electronic Theses and Dissertations

We surveyed four plant communities along an elevational gradient in the Front Range of the Colorado Rocky Mountains for long-term overstory and understory changes. Our results were compared to those found in 1981 and 1996. We evaluated changes in succession, elevational species migration and range expansion, community diversity, and composition. We related temporal floristic shifts to prior literature on disturbance history at each site. Over time, all communities changed significantly, though in different manners. This analysis shows that plant communities are changing in dynamic and idiosyncratic ways that correspond to individualistic distribution shifts. Moreover, we exhibit the necessity of comprehensively …

Vcu's Green Richmond Research, Nadia Rentia

AUCTUS: The Journal of Undergraduate Research and Creative Scholarship

The impact of urbanization on the dogwood tree was the VCU junior Kaitlyn Parkman’s focus as she researched hundreds of trees in Richmond.

Incorporating Risk Of Reinvasion To Prioritize Sites For Invasive Species Management, Todd R. Lookingbill, Emily S. Minor, Nadia Bukach, Joseph R. Ferrari, Lisa A. Wainger

Geography and the Environment Faculty Publications

The relationship between landscape pattern and the distribution and spread of exotic species is an important determinant of where and when management actions are best applied. We have developed an interdisciplinary approach for prioritizing treatment of harmful, nonnative, invasive plants in National Park landscapes of the Mid-Atlantic USA. The approach relies upon a detailed model of reinvasion risk that combines information on: (1) global factors representing park-level infestation from seed and sprout, (2) landscape factors including disturbance-based spread vectors and neighborhood seed density, and (3) local factors determining establishment probability based on habitat suitability. Global seed rain estimates are derived …

Variation In The Local Population Dynamics Of The Short-Lived Opuntia Macrorhiza (Cactaceae), Chirakkal V. Haridas, Kathleen H. Keeler, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Spatio-temporal variation in demographic rates can have profound effects for population persistence, especially for dispersal-limited species living in fragmented landscapes. Long-term studies of plants in such habitats help with understanding the impacts of fragmentation on population persistence but such studies are rare. In this work we reanalyzed demographic data from seven years of the short-lived cactus Opuntia macrorhiza var. macrorhiza at five plots in Boulder, Colorado. Previous work combining data from all years and all plots predicted a stable population (deterministic log λ ≈ 0). This approach assumed that all five plots were part of a single population. Since the …

Quantitative Trait Locus Analysis Of Unsaturated Fatty Acids In A Recombinant Inbred Population Of Soybean, Xianzhi Wang, Guo-Liang Jiang, Marci Green, Roy A. Scott, D. L. Hyten, P. B. Cregan

Department of Agronomy and Horticulture: Faculty Publications

Soybean [Glycine max (L.) Merr.] is an important oilseed crop which produces about 30 %of the world’s edible vegetable oil. The quality of soybean oil is determined by its fatty acid composition. Soybean oil high in oleic and low in linolenic fatty acids is desirable for human consumption and other uses. The objectives of this study were to identify quantitative trait loci (QTLs) for unsaturated fatty acids and to evaluate the genetic effects of single QTL and QTL combinations in soybean. A population of recombinant inbred lines derived from the cross of SD02-4-59 X A02-381100 was evaluated for fatty …

Transcriptomic And Physiological Characterization Of The Fefe Mutant Of Melon (Cucumis Melo) Reveals New Aspects Of Iron-Copper Crosstalk, Brian M. Waters, Samuel A. Mcinturf, Keenan Amundsen

Department of Agronomy and Horticulture: Faculty Publications

Iron (Fe) and copper (Cu) homeostasis are tightly linked across biology. In previous work, Fe deficiency interacted with Cu-regulated genes and stimulated Cu accumulation. The C940-fe (fefe) Fe-uptake mutant of melon (Cucumis melo) was characterized, and the fefe mutant was used to test whether Cu deficiency could stimulate Fe uptake. Wild-type and fefe mutant transcriptomes were determined by RNA-seq under Fe and Cu deficiency. FeFe-regulated genes included core Fe uptake, metal homeostasis, and transcription factor genes. Numerous genes were regulated by both Fe and Cu. The fefe mutant was rescued by high Fe or by …

Characterization Of Putative Defense Genes In Nonvascular Plants, Blaine Harlan

Undergraduate Honors Thesis Collection

Vascular plants have many known defenses against herbivory and pathogen infection. One inducible defense system that has been extensively studied in vascular plants is systemic acquired resistance (SAR), which is a plant-wide response that results in resistance to a wide range of pathogens Many genes that play a role in SAR have been characterized. Although several studies of plant-pathogen interactions in non-vascular plants have occurred, it was not until recently that the existence of SAR was shown in these plants. The goal of the present study was to confirm the presence of homologous defense genes in moss, and to study …

2014 Virginia Wildflower Of The Year: Coral Honeysuckle, Lonicera Sempervirens, W. John Hayden

Biology Faculty Publications

The flashy red flowers of coral honeysuckle beckon hummingbirds to their sweet nectar. Coral honeysuckle is a twining woody vine, usually climbing on other vegetation but sometimes trailing along the ground; older stems have papery-brown exfoliating bark.

Four Common Setaria Species Are Alternative Hosts For Clavibacter Michiganensis Subsp. Nebraskensis, Causal Agent Of Goss's Bacterial Wilt And Blight Of Corn, Craig B. Langemeier, Tamra A. Jackson-Ziems, Greg R. Kruger

Department of Plant Pathology: Faculty Publications

Goss’s bacterial wilt and blight, caused by Clavibacter michiganensis subsp. nebraskensis (Cmn), has reemerged as an important disease of Zea mays (corn) in the U.S. Midwest. Results from a 2011 multistate survey indicated that Setaria spp. (foxtail) were often present in corn fields with a history of Cmn. The objective of this research was to determine if Setaria spp. that are common in the Midwest are susceptible to infection by Cmn. In the greenhouse, seedlings of four Setaria spp., including S. viridis (green foxtail), S. faberi (giant foxtail), S. verticillata (bristly foxtail), and S. pumila (yellow foxtail), and Zea mays …

What’S New In Plant Pathology, Tamra A. Jackson-Ziems, Loren Giesler, Robert M. Harveson, Stephen N. Wegulo, Kevin Korus

Department of Plant Pathology: Faculty Publications

Disease Management Products

During the past year several new products have become available for disease management. The new products are summarized in Tables 1 and 2, as well as included in the 2014 Guide for Weed Management in Nebraska with Insecticide and Fungicide Information. In addition, fungicides labeled for use on sorghum and sunflower have also been added to the publication.

Table 1. New Foliar Fungicides

Table 2. New Seed Nematicide

Disease Identification and Management Resources

Ficotylus Laselvae N. Sp. (Tylenchomorpha: Anguinidae) Associated With Ficus Colubrinae In Costa Rica, Robin M. Giblin-Davis, Natsumi Kanzaki, Kerrie A. Davies, Weimin Ye, Yongsan Zeng, Barbara J. Center, Alejandro Esquivel, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

Ficotylus laselvae n. sp. was recovered from under the bracts of figs (syconia) of Ficus colubrinae from La Selva, Costa Rica, during a survey of nematode rainforest biodiversity and is described herein. This is only the second report of an association between the nematode suborder Tylenchina and the sycones of figs. Previous reports of most nematode associates of the sycones of figs have been from the lumen and involved transmission by female fig wasp pollinators (Agaonidae) during pollination/oviposition (e.g., Schistonchus and Parasitodiplogaster spp.). The association between F. laselvae n. sp. and Ficus colubrinae may involve an invertebrate host, …

Wheat Streak Mosaic Virus Infects Systemically Despite Extensive Coat Protein Deletions: Identification Of Virion Assembly And Cell-To-Cell Movement Determinants, Satyanarayana Tatineni, Frank A. Kovacs, Roy C. French

Department of Plant Pathology: Faculty Publications

Viral coat proteins function in virion assembly and virus biology in a tightly coordinated manner with a role for virtually every amino acid. In this study, we demonstrated that the coat protein (CP) of Wheat streak mosaic virus (WSMV; genus Tritimovirus, family Potyviridae) is unusually tolerant of extensive deletions, with continued virion assembly and/or systemic infection found after extensive deletions are made. A series of deletion and point mutations was created in the CP cistron of wild-type and/or green fluorescent protein-tagged WSMV, and the effects of these mutations on cell-to-cell and systemic transport and virion assembly of WSMV …

Phytophthora Ramorum, Sydney E. Everhart, Javier F. Tabima, Niklaus J. Grünwald

Department of Plant Pathology: Faculty Publications

Phytophthora ramorum is a recently emerged plant pathogen and causal agent of one of the most destructive and devastating diseases currently affecting US horticulture and forests (Rizzo et al. 2002, 2005). This oomycete pathogen was discovered in Marin County, California, in the mid-1990s, causing sudden oak death on coast live oak (Quercus agrifolia) and tanoak (Notholithocarpus densiflorus) and simultaneously discovered in Europe causing foliar blight on Rhododendron and Viburnum (Rizzo et al. 2002; Werres et al. 2001). It is now known to affect more than 100 plant species, including economically important nursery and forest host species …

Boron Nutrition Of Burley And Dark Tobacco, Laura Ann Frakes Mitchell

Theses and Dissertations--Plant and Soil Sciences

The incidences of suspected Boron (B) deficiency have increased recently in Kentucky tobacco fields, potentially due to recent changes in management practices. The symptoms observed in the field include; hollow stalk, stunted growth, deformed or no bud formation, small slits on the lower leaf midrib and uncontrollable breaking of the midrib approximately two inches from the stalk. B is a micronutrient tobacco needs in minute amounts, however excessive additions of B could cause toxicity. The objectives of this work were to 1) establish critical points for B sufficiency, 2) describe and define B deficiency and toxicity symptoms and 3) develop …

Response Of Fusarium Thapsinum To Sorghum Brown Midrib Lines And To Phenolic Metabolites, Deanna L. Funnell-Harris, Scott E. Sattler, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Sorghum lines were bred for reduced lignin for cellulosic bioenergy uses, through the incorporation of brown midrib (bmr)6 or -12 into two backgrounds (RTx430 and Wheatland) as either single or doublemutant lines. When these lines were assessed for resistance to Fusarium thapsinum stalk rot, a cause of lodging, they were as resistant to F. thapsinum as the near-isogenic wild type. Peduncles of newly identified bmr lines from an ethyl-methanesulfonate-mutagenized population, inoculated with F. thapsinum, were as resistant as the wild-type line, BTx623. One bmr line (1107) had significantly smaller mean lesion lengths than BTx623, suggesting that a mutation …