Plant Pathology Commons^™

Screen Of Non-Annotated Small Secreted Proteins Of Pseudomonas Syringae Reveals A Virulence Factor That Inhibits Tomato Immune Proteases, Takayuki Shindo, Farnusch Kaschani, Fan Yang, Judit Kovács, Fang Tian, Jiorgos Kourelis, Tram Ngoc Hong, Tom Colby, Mohammed Shabab, Rohini Chawla, Selva Kumari, Muhammed Ilyas, Anja C. Hörger, James R. Alfano, Renier A. L. Van Der Hoorn

Center for Plant Science Innovation: Faculty Publications

Pseudomonas syringae pv. tomato DC3000 (PtoDC3000) is an extracellular model plant pathogen, yet its potential to produce secreted effectors that manipulate the apoplast has been under investigated. Here we identified 131 candidate small, secreted, non-annotated proteins from the PtoDC3000 genome, most of which are common to Pseudomonas species and potentially expressed during apoplastic colonization. We produced 43 of these proteins through a custom-made gateway-compatible expression system for extracellular bacterial proteins, and screened them for their ability to inhibit the secreted immune protease C14 of tomato using competitive activity-based protein profiling. This screen revealed C14-inhibiting protein-1 (Cip1), which contains …

Residues Responsible For The Selectivity Of Α-Conotoxins For Ac-Achbp Or Nachrs, Bo Lin, Shi-Hua Xiang, Mengsen Li

Center for Plant Science Innovation: Faculty Publications

Nicotinic acetylcholine receptors (nAChRs) are targets for developing new drugs to treat severe pain, nicotine addiction, Alzheimer disease, epilepsy, etc. α-Conotoxins are biologically and chemically diverse. With 12–19 residues and two disulfides, they can be specifically selected for different nAChRs. Acetylcholine-binding proteins from Aplysia californica (Ac-AChBP) are homologous to the ligand-binding domains of nAChRs and pharmacologically similar. X-ray structures of the α-conotoxin in complex with Ac-AChBP in addition to computer modeling have helped to determine the binding site of the important residues of α-conotoxin and its affinity for nAChR subtypes. Here, we present the various α-conotoxin residues that are selective …

Screen Of Non-Annotated Small Secreted Proteins Of Pseudomonas Syringae Reveals A Virulence Factor That Inhibits Tomato Immune Proteases, Takayuki Shindo, Farnusch Kaschani, Fan Yang, Judit Kovács, Fang Tian, Jiorgos Kourelis, Tram Ngoc Hong, Tom Colby, Mohammed Shabab, Rohini Chawla, Selva Kumari, Muhammed Ilyas, Anja C. Hörger, James R. Alfano, Renier A. L. Van Der Hoorn

Center for Plant Science Innovation: Faculty Publications

Pseudomonas syringae pv. tomato DC3000 (PtoDC3000) is an extracellular model plant pathogen, yet its potential to produce secreted effectors that manipulate the apoplast has been under investigated. Here we identified 131 candidate small, secreted, non-annotated proteins from the PtoDC3000 genome, most of which are common to Pseudomonas species and potentially expressed during apoplastic colonization. We produced 43 of these proteins through a custom-made gateway-compatible expression system for extracellular bacterial proteins, and screened them for their ability to inhibit the secreted immune protease C14 of tomato using competitive activity-based protein profiling. This screen revealed C14-inhibiting protein-1 (Cip1), which contains motifs of …

Limited Mitogenomic Degradation In Response To A Parasitic Lifestyle In Orobanchaceae, Weishu Fan, Andan Zhu, Melisa Kozaczek, Neethu Shah, Natalia Pabón-Mora, Favio González, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

In parasitic plants, the reduction in plastid genome (plastome) size and content is driven predominantly by the loss of photosynthetic genes. The first completed mitochondrial genomes (mitogenomes) from parasitic mistletoes also exhibit significant degradation, but the generality of this observation for other parasitic plants is unclear. We sequenced the complete mitogenome and plastome of the hemiparasite Castilleja paramensis (Orobanchaceae) and compared them with additional holoparasitic, hemiparasitic and nonparasitic species from Orobanchaceae. Comparative mitogenomic analysis revealed minimal gene loss among the seven Orobanchaceae species, indicating the retention of typical mitochondrial function among Orobanchaceae species. Phylogenetic analysis demonstrated that the mobile cox1 …

Identification Of Homogentisate Dioxygenase As A Target For Vitamin E Biofortification In Oilseeds, Minviluz G. Stacey, Rebecca E. Cahoon, Hanh T. Nguyen, Yaya Cui, Shirley Sato, Cuong T. Nguyen, Nongnat Phoka, Kerry M. Clark, Yan Liang, Joe Forrester, Josef Batek, Phat Tien Do, David A. Sleper, Thomas E. Clemente, Edgar B. Cahoon, Gary Stacey

Center for Plant Science Innovation: Faculty Publications

Soybean (Glycine max) is a major plant source of protein and oil and produces important secondary metabolites beneficial for human health. As a tool for gene function discovery and improvement of this important crop, a mutant population was generated using fast neutron irradiation. Visual screening of mutagenized seeds identified a mutant line, designated MO12, which produced brown seeds as opposed to the yellow seeds produced by the unmodified Williams 82 parental cultivar. Using forward genetic methods combined with comparative genome hybridization analysis, we were able to establish that deletion of the GmHGO1 gene is the genetic basis of …

Snrna 3' End Processing By A Cpsf73- Containing Complex Essential For Development In Arabidopsis, Yunfeng Liu, Shengjun Li, Yuan Chen, Athen N. Kimberlin, Edgar B. Cahoon, Bin Yu

Center for Plant Science Innovation: Faculty Publications

Uridine-rich small nuclear RNAs (snRNAs) are the basal components of the spliceosome and play essential roles in splicing. The biogenesis of the majority of snRNAs involves 3’ end endonucleolytic cleavage of the nascent transcript from the elongating DNA-dependent RNA ploymerase II. However, the protein factors responsible for this process remain elusive in plants. Here, we show that DEFECTIVE in snRNA PROCESSING 1 (DSP1) is an essential protein for snRNA 3’ end maturation in Arabidopsis. A hypomorphic dsp1-1 mutation causes pleiotropic developmental defects, impairs the 3’ end processing of snRNAs, increases the levels of snRNA primary transcripts (pre-snRNAs), and alters …

Evolutionary Dynamics Of The Plastid Inverted Repeat: The Effects Of Expansion, Contraction, And Loss On Substitution Rates, Andan Zhu, Wenhu Guo, Weishu Fan, Jeffrey P. Mower

Center for Plant Science Innovation: Faculty Publications

• Rates of nucleotide substitution were previously shown to be several times slower in the plastid inverted repeat (IR) compared with single-copy (SC) regions, suggesting that the IR provides enhanced copy-correction activity.

• To examine the generality of this synonymous rate dependence on the IR, we compared plastomes from 69 pairs of closely related species representing 52 families of angiosperms, gymnosperms, and ferns.

• We explored the breadth of IR boundary shifts in land plants and demonstrate that synonymous substitution rates are, on average, 3.7 times slower in IR genes than in SC genes. In addition, genes moved from the SC into the …

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The Role Of G-Protein Signaling In Pathogenesis In Cercospora Zeae-Maydis, Brant Smith

Graduate Theses and Dissertations

Gray leaf spot, caused by Cercospora zeae-maydis, is one of the most destructive foliar diseases of maize worldwide. C. zeae-maydis orients hyphal growth towards stomata (stomatal tropism) and forms infectious structures (appressoria) that are necessary for successful infection. Although some genes involved in pathogenesis in C. zeae-maydis have been identified, the molecular mechanisms are not well understood. In fungi, heterotrimeric G-proteins consist of three subunits (α, β, and γ) and mediate responses to environmental stimuli. They regulate diverse functions, including nutrient detection, virulence, fungal development, conidiation, secondary metabolism, and pathogenesis in many plant pathogenic fungi. This research explored the role …

Chlorophyll Synthase Under Epigenetic Surveillance Is Critical For Vitamin E Synthesis, And Altered Expression Affects Tocopherol Levels In Arabidopsis, Chunyu Zhang, Wei Zhang, Guodong Ren, Denli Li, Rebecca E. Cahoon, Ming Chen, Yongming Zhou, Bin Yu, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Chlorophyll synthase catalyzes the final step in chlorophyll biosynthesis: the esterification of chlorophyllide with either geranylgeranyl diphosphate or phytyl diphosphate (PDP). Recent studies have pointed to the involvement of chlorophyll-linked reduction of geranylgeranyl by geranylgeranyl reductase as a major pathway for the synthesis of the PDP precursor of tocopherols. This indirect pathway of PDP synthesis suggests a key role of chlorophyll synthase in tocopherol production to generate the geranylgeranyl-chlorophyll substrate for geranylgeranyl reductase. In this study, contributions of chlorophyll synthase to tocopherol formation in Arabidopsis (Arabidopsis thaliana) were explored by disrupting and altering expression of the corresponding gene …

Osmotic Stress Induces Phosphorylation Of Histone H3 At Threonine 3 In Pericentromeric Regions Of Arabidopsis Thaliana, Zhen Wang, Juan Armando Casas-Mollano, Jianping Xu, Jean-Jack M. Riethoven, Chi Zhang, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Histone phosphorylation plays key roles in stress-induced transcriptional reprogramming in metazoans but its function(s) in land plants has remained relatively unexplored. Here we report that an Arabidopsis mutant defective in At3g03940 and At5g18190, encoding closely related Ser/Thr protein kinases, shows pleiotropic phenotypes including dwarfism and hypersensitivity to osmotic/salt stress. The double mutant has reduced global levels of phosphorylated histone H3 threonine 3 (H3T3ph), which are not enhanced, unlike the response in the wild type, by drought-like treatments. Genome-wide analyses revealed increased H3T3ph, slight enhancement in trimethylated histone H3 lysine 4 (H3K4me3), and a modest decrease in histone H3 occupancy …

Osmotic Stress Induces Phosphorylation Of Histone H3 At Threonine 3 In Pericentromeric Regions Of Arabidopsis Thaliana, Zhen Wang, Juan Casas-Mollano, Jianping Xu, Jean-Jack Riethoven, Chi Zhang, Heriberto D. Cerutti

Center for Plant Science Innovation: Faculty Publications

Histone phosphorylation plays key roles in stress-induced transcriptional reprogramming in metazoans but its function(s) in land plants has remained relatively unexplored. Here we report that an Arabidopsis mutant defective in At3g03940 and At5g18190, encoding closely related Ser/Thr protein kinases, shows pleiotropic phenotypes including dwarfism and hypersensitivity to osmotic/salt stress. The double mutant has reduced global levels of phosphorylated histone H3 threonine 3 (H3T3ph), which are not enhanced, unlike the response in the wild type, by drought-like treatments. Genome-wide analyses revealed increased H3T3ph, slight enhancement in trimethylated histone H3 lysine 4 (H3K4me3), and a modest decrease in histone H3 occupancy …

Combinatorial Effects Of Fatty Acid Elongase Enzymes On Nervonic Acid Production In Camelina Sativa, Dongxin Huai, Yuanyuan Zhang, Chunyu Zhang, Edgar B. Cahoon, Yongming Zhou

Center for Plant Science Innovation: Faculty Publications

Very long chain fatty acids (VLCFAs) with chain lengths of 20 carbons and longer provide feedstocks for various applications; therefore, improvement of VLCFA contents in seeds has become an important goal for oilseed enhancement. VLCFA biosynthesis is controlled by a multi-enzyme protein complex referred to as fatty acid elongase, which is composed of β-ketoacyl-CoA synthase (KCS), β-ketoacyl-CoA reductase (KCR), β-hydroxyacyl-CoA dehydratase (HCD) and enoyl reductase (ECR). KCS has been identified as the ratelimiting enzyme, but little is known about the involvement of other three enzymes in VLCFA production. Here, the combinatorial effects of fatty acid elongase enzymes on VLCFA production …

Sumoylation By A Stress-Specific Small Ubiquitin-Like Modifier E2 Conjugase Is Essential For Survival Of Chlamydomonas Reinhardtii Under Stress Conditions, Amy R. Knobbe, Kempton M. Horken, Thomas M. Plucinak, Eniko Balassa, Heriberto Cerutti, Donald P. Weeks

Center for Plant Science Innovation: Faculty Publications

Posttranslational modification of proteins by small ubiquitin-like modifier (SUMO) is required for survival of virtually all eukaryotic organisms. Attachment of SUMO to target proteins is catalyzed by SUMO E2 conjugase. All haploid or diploid eukaryotes studied to date possess a single indispensable SUMO conjugase. We report here the unanticipated isolation of a Chlamydomonas reinhardtii (mutant5 [mut5]), in which the previously identified SUMO conjugase gene C. reinhardtii ubiquitin-conjugating enzyme9 (CrUBC9) is deleted. This surprising mutant is viable and unexpectedly displays a pattern of protein SUMOylation at 25°C that is essentially identical to wild-type cells. However, unlike wild-type …

Toward Production Of Jet Fuel Functionality In Oilseeds: Identification Of Fatb Acyl-Acyl Carrier Protein Thioesterases And Evaluation Of Combinatorial Expression Strategies In Camelina Seeds, Hae Jin Kim, Jillian E. Silva, Hieu Sy Vu, Keithanne Mockaitis, Jeong-Won Nam, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Seeds of members of the genus Cuphea accumulate medium-chain fatty acids (MCFAs; 8:0–14:0). MCFA- and palmitic acid- (16:0) rich vegetable oils have received attention for jet fuel production, given their similarity in chain length to Jet A fuel hydrocarbons. Studies were conducted to test genes, including those from Cuphea, for their ability to confer jet fuel-type fatty acid accumulation in seed oil of the emerging biofuel crop Camelina sativa. Transcriptomes from Cuphea viscosissima and Cuphea pulcherrima developing seeds that accumulate >90% of C8 and C10 fatty acids revealed three FatB cDNAs (CpuFatB3, CvFatB1, and CpuFatB4 …

Fungal Morphogenesis, Xiaorong Lin, J. Andrew Alspaugh, Haoping Liu, Steven D. Harris

Center for Plant Science Innovation: Faculty Publications

Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and …

Gene Silencing In Microalgae: Mechanisms And Biological Roles, Eun-Jeong Kim, Xinrong Ma, Heriberto Cerutti

Center for Plant Science Innovation: Faculty Publications

Microalgae exhibit enormous diversity and can potentially contribute to the production of biofuels and high value compounds. However, for most species, our knowledge of their physiology, metabolism, and gene regulation is fairly limited. In eukaryotes, gene silencing mechanisms play important roles in both the reversible repression of genes that are required only in certain contexts and the suppression of genome invaders such at transposons. The recent sequencing of several algal genomes is providing insights into the complexity of these mechanisms in microalgae. Collectively, glaucophyte, red, and green microalgae contain the machineries involved in repressive histone H3 lysine methylation, DNA cytosine …

Sirna-Directed Dna Methylation In Plants, Meng Xie, Bin Yu

Center for Plant Science Innovation: Faculty Publications

DNA cytosine methylationis an important epigenetic process that is correlated with transgene silencing, transposon suppression, and gene imprinting. In plants, small interfering RNAs (siRNAs) can trigger DNA methylation at loci containing their homolog sequences through a process called RNAdirected DNA methylation (RdDM). In canonical RdDM, 24 nucleotide (nt) siRNAs (ra-siRNAs) will be loaded into their effector protein called ARGONAUTE 4 (AGO4) and subsequently targeted to RdDM loci through base-pairing with the non-coding transcripts produced by DNA-directed RNA Polymerase V. Then, the AGO4-ra-siRNA will recruit the DNA methyltransferase to catalyze de novo DNA methylation. Recent studies also identified non-canonical RdDM pathways …

The Role Of Ethylene In Plant Responses To K+ Deficiency, Daniel P. Schachtman

Center for Plant Science Innovation: Faculty Publications

Potassium is an essential macronutrient that is involved in regulating turgor , in driving plant growth, and in modulating enzyme activation. The changes in root morphology, root function, as well as cellular and molecular responses to low potassium conditions have been studied in the model plant Arabidopsis and in other plant species. In Arabidopsis ethylene plays a key role in roots in the transduction of the low potassium signal, which results in altered root function and growth. The first clues regarding the role of ethylene were detected through transcriptional profiling experiments showing changes in the expression of genes related to …

Redirection Of Metabolic Flux For High Levels Of Omega-7 Monounsaturated Fatty Acid Accumulation In Camelina Seeds, Huu Tam Nguyen, Hyunwoo Park, Karen L. Koster, Rebecca E. Cahoon, Hanh Nguyen, John Shanklin, Thomas E. Clemente, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Seed oils enriched in omega-7 monounsaturated fatty acids, including palmitoleic acid (16:1Δ9) and cis-vaccenic acid (18:1Δ11), have nutraceutical and industrial value for polyethylene production and biofuels. Existing oilseed crops accumulate only small amounts (<2%) of these novel fatty acids in their seed oils. We demonstrate a strategy for enhanced production of omega-7 monounsaturated fatty acids in camelina (Camelina sativa) and soybean (Glycine max) that is dependent on redirection of metabolic flux from the typical Δ9 desaturation of stearoyl (18:0)-acyl carrier protein (ACP) to Δ9 desaturation of palmitoyl (16:0)-acyl carrier protein (ACP) and coenzyme A (CoA). This was achieved by seed-specific co-expression of a mutant Δ9-acyl-ACP and an acyl-CoA desaturase with high specificity for 16:0-ACP and CoA substrates, respectively. This strategy was most effective in camelina where seed oils with ~17% omega-7 monounsaturated fatty acids were obtained.

Further increases in omega-7 fatty acid accumulation to 60–65% of the total fatty acids in camelina seeds were achieved by inclusion of seed-specific suppression of 3-keto-acyl-ACP synthase II and the FatB 16:0-ACP thioesterase genes to increase substrate pool sizes of 16:0-ACP for the Δ9-acyl-ACP desaturase and by blocking C18 fatty acid elongation. Seeds from these lines also had total saturated fatty acids reduced to ~5% of …

Production Of High Levels Of Poly-3-Hydroxybutyrate In Plastids Of Camelina Sativa Seeds, Meghna R. Malik, Wenyu Tang, Nii Patterson, Jihong Tang, Rachel L. Wellinghoff, Mary L. Preuss, Claire Burkitt, Nirmala Sharma, Yuanyuan Ji, Joseph M. Jez, Oliver P. Peoples, Jan G. Jaworski, Edgar B. Cahoon, Kristi D. Snell

Center for Plant Science Innovation: Faculty Publications

Poly-3-hydroxybutyrate (PHB) production in plastids of Camelina sativa seeds was investigated by comparing levels of polymer produced upon transformation of plants with five different binary vectors containing combinations of five seed-specific promoters for expression of transgenes. Genes encoding PHB biosynthetic enzymes were modified at the N-terminus to encode a plastid targeting signal. PHB levels of up to 15% of the mature seed weight were measured in single sacrificed T1 seeds with a genetic construct containing the oleosin and glycinin promoters.

A more detailed analysis of the PHB production potential of two of the best performing binary vectors in a Camelina …

Toward Production Of Jet Fuel Functionality In Oilseeds: Identification Of Fatb Acyl-Acyl Carrier Protein Thioesterases And Evaluation Of Combinatorial Expression Strategies In Camelina Seeds, Hae Jin Kim, Jillian E. Silva, Hieu Sy Vu, Keithanne Mockaitis, Jeong-Won Nam, Edgar B. Cahoon

Center for Plant Science Innovation: Faculty Publications

Seeds of members of the genus Cuphea accumulate medium-chain fatty acids (MCFAs; 8:0–14:0). MCFA- and palmitic acid- (16:0) rich vegetable oils have received attention for jet fuel production, given their similarity in chain length to Jet A fuel hydrocarbons. Studies were conducted to test genes, including those from Cuphea, for their ability to confer jet fuel-type fatty acid accumulation in seed oil of the emerging biofuel crop Camelina sativa. Transcriptomes from Cuphea viscosissima and Cuphea pulcherrima developing seeds that accumulate >90% of C8 and C10 fatty acids revealed three FatB cDNAs (CpuFatB3, CvFatB1, and CpuFatB4) …

Microrna Biogenesis, Degradation And Activity In Plants, Meng Xie, Shuxin Zhang, Bin Yu

Center for Plant Science Innovation: Faculty Publications

microRNAs (miRNAs) are important regulators of gene expression. After excised from primary miRNA transcript by dicer-like1 (DCL1, an RNAse III enzyme), miRNAs bind and guide their effector protein named argonaute 1 (AGO1) to silence the expression of target RNAs containing their complementary sequences in plants. miRNA levels and activities are tightly controlled to ensure their functions in various biological processes such as development, metabolism and responses to abiotic and biotic stresses. Studies have identified many factors that involve in miRNA accumulation and activities. Characterization of these factors in turn greatly improves our understanding of the processes related to miRNAs. Here, …

Modifications Of Membrane Lipids In Response To Wounding Of Arabidopsis Thaliana Leaves, Hieu Sy Vu, Rebecca Roston, Sunitha Shiva, Manhoi Hur, Eve Syrkin Wurtele, Xuemin Wang, Jyoti Shah, Ruth Welti

Center for Plant Science Innovation: Faculty Publications

Mechanical wounding of Arabidopsis thaliana leaves results in modifications of most membrane lipids within 6 hours. Here, we discuss the lipid changes, their underlying biochemistry, and possible relationships among activated pathways. New evidence is presented supporting the role of the processive galactosylating enzyme SENSITIVE TO FREEZING2 in the wounding response.

The Taurine Biosynthetic Pathway Of Microalgae, Rahul Tevatia, James Allen, Deepak Rudrappa, Derrick White, Thomas E. Clemente, Heriberto Cerutti, Yaşar Demirel, Paul H. Blum

Center for Plant Science Innovation: Faculty Publications

Taurine (2-aminoethanesulfonic acid) is an amino acid–like compound widely distributed in animals and an essential nutrient in some species. Targeted metabolomics of marine and freshwater microalgae combined with medium supplementation identified biosynthetic pathway intermediates and necessary catalytic activities. Genomic analysis was then used to predict the first taurine biosynthetic pathway in these organisms. MRM-based electrospray ionization (ESI) LC–MS/MS analysis demonstrated that taurine is synthesized using a carbon backbone from L-serine combined with sulfur derived from sulfate. Metabolite analysis showed a nonuniform pattern in levels of pathway intermediates that were both species and supplement dependent. While increased culture salinity raised taurine …

Generation Of An Attenuated, Cross-Protective Pepino Mosaic Virus Variant Through Alignment-Guided Mutagenesis Of The Viral Capsid Protein, Godwill M. Chewachong, Sally A. Miller, Joshua J. Blakeslee, David M. Francis, Thomas Jack Morris, Feng Qu

School of Biological Sciences: Faculty Publications

Mild variants of many viruses are able to protect infected plants from subsequent invasion by more severe variants of the same viruses through a process known as cross-protection. In the past, the cross-protective viral variants were commonly derived from mild field isolates that were sometimes genetically heterogeneous, providing variable levels of crossprotection. Here, we report a novel approach to rapidly generate crossprotective variants of the tomato-infecting Pepino mosaic virus (PepMV) independently of the availability of mild field isolates. Our approach sought to attenuate PepMV by mutating less conserved amino acid residues of the abundantly produced capsid protein (CP). These less-conserved …

Characterization Of A Novel Fungal-Specific Gene, Fug1, In Fusarium Verticillioides, John Byron Ridenour

Graduate Theses and Dissertations

Filamentous fungi are responsible for numerous plant and animal diseases. The filamentous ascomycete Fusarium verticillioides is a globally important pathogen of maize, capable of causing severe yield reductions and economic losses. Also of substantial concern is the contamination of infected kernels with fumonisins, toxic secondary metabolites linked to toxicoses in humans and livestock. The number of sequenced fungal genomes is rapidly increasing. However, functional characterization of fungal genes has not progressed at a comparable rate. In pathogenic fungi, uncharacterized genes represent a source for novel virulence factors or anti-fungal targets. Therefore, to fully understand the genetic mechanisms underlying fungal pathogenesis, …

Characterization Of Microorganisms From Alfalfa Seeds Inoculants, Benedicte Diatta, Kalianna Kennoy, Silvia Rossbach

Research and Creative Activities Poster Day

Atmospheric nitrogen fixation can be accomplished by free living microorganisms or by symbiosis between legume plants and rhizobia. The symbiosis between the alfalfa plant and Sinorhizobium meliloti is one example of the symbiotic relationship between legume plants and rhizobia. During the symbiosis, the rhizobia fix nitrogen for the plant and the plant in return provides carbohydrates for the bacteria. In order to maximize the plant’s yield in agriculture, recent technologies used include seed inoculants. Seed inoculation methods rely on coating the seeds with plant-growth promoting bacteria. Besides nitrogen-fixing bacteria, the seeds may also be coated with microorganisms aiding in mineral …

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 …