Life Sciences Commons^™

Microbiome Of The Cool Season Forage Grass Timothy (Phleum Pratense L.) And Its Potential Role In Stress Tolerance, Dina Saleh, Suha Jabaji, Philippe Seguin

IGC Proceedings (1997-2023)

The functional attributes of the microbiome associated with timothy for growth promotion properties, antimicrobial and biosurfactant capacities were characterized. A total of 254 culturable bacteria were identified by 16S rRNA sequencing and grouped into 16 taxa that shared high homology of 98–99% with other known sequences. The majority of bacterial isolates exhibited multifunctional growth promotion attributes and plant stress improvement. The selection of competent and compatible strains for application in forage production is dependent on the recognition of root exudates and motility towards the roots, attachment to the root surface, formation of biofilm, penetration, and colonization of internal tissues. We …

Root Exudates Alter The Expression Of Diverse Metabolic, Transport, Regulatory, And Stress Response Genes In Rhizosphere Pseudomonas, Olga V. Mavrodi, Janiece R. Mcwilliams, Jacob O. Peter, Anna Berim, Karl A. Hassan, Liam D.H. Elbourne, Melissa K. Letourneau, David R. Gang, Ian T. Paulsen, David M. Weller, Linda S. Thomashow, Alex S. Flynt, Dmitri V. Mavrodi

Faculty Publications

Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model …

Identifying Brachypodium Distachyon Proteins Interacting With Histone Deacetylase Bdhd1, Alberto Giovanni Torrez

Electronic Thesis and Dissertation Repository

Current evidence has revealed the involvement of epigenetic mechanisms, including histone deacetylases (HDACs), in plant stress responses. In Arabidopsis thaliana, HDA19, belonging to the RPD3/HDA1 class, interacts with transcription factors to form repressor complexes. HDAC research mainly exists for dicotyledons, whereas research on monocotyledons is limited. Brachypodium distachyon is used as a model plant to investigate questions unique to monocot crops. BdHD1 is the closest homologous gene to HDA19 in B. distachyon. This study investigated potential protein-protein interactions between BdHD1 and each of BdMYB22, BdWRKY24, and BdHOS15. Protein interactions were investigated using yeast two-hybrid (Y2H) and bimolecular fluorescence …

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Engineering Linear, Branched-Chain Triterpene Metabolism In Monocots, Chase Kempinski, Zuodong Jiang, Garrett Zinck, Shirley J. Sato, Zhengxiang Ge, Thomas E. Clemente, Joseph Chappell

Department of Agronomy and Horticulture: Faculty Publications

Triterpenes are thirty-carbon compounds derived from the universal five-carbon prenyl precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Normally, triterpenes are synthesized via the mevalonate (MVA) pathway operating in the cytoplasm of eukaryotes where DMAPP is condensed with two IPPs to yield farnesyl diphosphate (FPP), catalyzed by FPP synthase (FPS). Squalene synthase (SQS) condenses two molecules of FPP to generate the symmetrical product squalene, the first committed precursor to sterols and most other triterpenes. In the green algae Botryococcus braunii, two FPP molecules can also be condensed in an asymmetric manner yielding the more highly branched triterpene, botryococcene. Botryococcene …

Grass-Specific Mechanisms Of Iron Uptake: Investigation Of Phytosiderophore Transporters And Discovery Of Novel Iron Deficiency Loci, David Chan Rodriguez

Doctoral Dissertations

Iron-deficiency anemia is one of the most prevalent forms of malnutrition worldwide, affecting 1.62 billion people, with the population in developing countries being the most affected. Iron is equally vital in plants to perform essential functions such as photosynthesis. Crop grasses form part of everyday human nutrition, contribute fundamentally to human caloric intake, and, in some parts of the world, are the primary source of food. Grasses acquire iron from the soil by secreting chelator molecules called phytosiderophores to solubilize iron, making it available to be transported by the Yellow Stripe1 (YS1) transporter. In this dissertation, I studied aspects of …

Brachypodium Distachyon Histone Deacetylase Bdhd1: A Positive Regulator In Aba Sensitivity And Drought Tolerance, Jingpu Song

Electronic Thesis and Dissertation Repository

Despite evidence that specific histone deacetylases (HDACs) play important roles in the abiotic stress responses of plants, their roles in the stress responses of monocot plants remain largely unexplored. I investigated a HDAC gene, Bradi3g08060 (BdHD1), in the monocot Brachypodium distachyon (Brachypodium). The Brachypodium BdHD1-overexpression (OE) plants displayed a hypersensitive phenotype to abscisic acid (ABA) and exhibited higher survival under drought conditions. Conversely, the BdHD1-RNAi plants were insensitive to ABA and had low survival under drought stress. Based on ChIP-Seq at the genome-wide level, overexpressing BdHD1 led to lower H3K9 acetylation at the …

Tof-Sims Analysis Of Plant Seed Interactions With Plant Growth-Promoting Bacteria, Tammy Pheuphong, Rachel Komorek, Xiao-Ying Yu

STAR Program Research Presentations

The use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) in plant biology is a relatively unexplored and quickly developing field. The majority of research in plant SIMS involves the application of ToF-SIMS to study dried wood tissues, and only a handful of studies apply SIMS on plant stems, roots, and/or seeds. Our project provides a brief description and review of previous work using SIMS on plant stems, roots, and/or seeds, along with an emphasis on the sample preparation in each study. Additionally, the use of Brachypodium distachyon (Brachypodium) as a model system for research on grasses has also become more …

Engineering Linear, Branched-Chain Triterpene Metabolism In Monocots, Chase Kempinski, Zuodong Jiang, Garrett Zinck, Shirley J. Sato, Zhengxiang Ge, Thomas E. Clemente, Joe Chappell

Department of Agronomy and Horticulture: Faculty Publications

Triterpenes are thirty-carbon compounds derived from the universal five-carbon prenyl precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Normally, triterpenes are synthesized via the mevalonate (MVA) pathway operating in the cytoplasm of eukaryotes where DMAPP is condensed with two IPPs to yield farnesyl diphosphate (FPP), catalyzed by FPP synthase (FPS). Squalene synthase (SQS) condenses two molecules of FPP to generate the symmetrical product squalene, the first committed precursor to sterols and most other triterpenes. In the green algae Botryococcus braunii, two FPP molecules can also be condensed in an asymmetric manner yielding the more highly branched triterpene, botryococcene. Botryococcene …

Evaluation Of The Water Stress-Inducible Promoter Wsi18 In The Model Monocot Brachypodium Distachyon, Patrick D. Langille

Electronic Thesis and Dissertation Repository

Water deficit-inducible promoters that function in multiple species are valuable components for engineering stress-tolerant crops. Wsi18 is a water deficit-inducible promoter native to Oryza sativa. In this study, Brachypodium distachyon (B. distachyon) was used to determine if Wsi18 retained its water deficit-inducible characteristics in another monocot. Transgenic B. distachyon plants, in which the Wsi18 promoter drove the expression of the uidA reporter gene, were developed and exposed to osmotic stress generated by mannitol, salt stress conditions, and the water deficit-signaling phytohormone abscisic acid (ABA). GUS histochemical assays demonstrated increased uidA expression in the leaves and stem of …

Biochemistry And Evolution Of The Phytohormone-Methylating Sabath Methyltransferase In Plants, Minta Chaiprasongsuk

Doctoral Dissertations

Known members of Phytohormone-methylating compounds are plant synthesis compounds that serve as attractants of other living organisms beneficial to the plants or as defense against other biotic as well as abiotic agents. To increase their fitness and survival in a stressful environment plants produce distinct sets of phytohormone-methylating compounds. Plant genomes can encode the necessary enzymes to acquire the ability to make new specialized compounds during evolution. This dissertation aims to investigate the biochemical and biological functions and evolution of SABATH genes in different lineages of plants. Black cottonwood, Brachypodium and Norway spruce genome were used as the model for …

Insights Into Triterpene Metabolism In Model Monocotyledonous And Oilseed Plants Genetically Engineered With Genes From Botryococcus Braunii, Chase F. Kempinski

Theses and Dissertations--Plant and Soil Sciences

Isoprenoids are one of the most diverse classes of natural products and are all derived from universal five carbon, prenyl precursors. Squalene and botryococcene are linear, hydrocarbon triterpenes (thirty carbon compounds with six prenyl units) that have industrial and medicinal values. Squalene is produced by all eukaryotes as it is the first committed precursor to sterols, while botryococcene is uniquely produced by the green algae, Botryococcus braunii (race B). Natural sources for these compounds exist, but there is a desire for more renewable production platforms. The model plant Arabidopsis thaliana was engineered to accumulate botryococcene and squalene in its oil …

Probing The Plant Cell Wall With Herbicides: A Chemical Genetics Approach, Chad B. Brabham

Theses and Dissertations--Plant and Soil Sciences

The primary cell wall is a highly organized multi-layered matrix of polysaccharides (cellulose, hemi-cellulose, and pectin). The ability of the rigid cell wall to sufficiently loosen to allow growth is a complex process that differs considerably between grasses monocots and dicots. Cellulose is the major structural component required for anisotropic cell expansion and is synthesized by CELLULOSE SYNTHASE A (CesA) proteins. Here, our objectives were two-fold: 1) dissect cell walls and cellulose biosynthesis in dicots and grasses using chemical biology and reverse genetic approaches 2) characterize and classify the inhibitory mechanisms of cellulose biosynthesis inhibitors (CBIs). A reverse genetics TILLING …

Understanding The Transcriptional Regulation Of Secondary Cell Wall Biosynthesis In The Model Grass Brachypodium Distachyon, Pubudu Handakumbura

Doctoral Dissertations

Secondary cell wall synthesis occurs in specialized cell types following completion of cell enlargement. By virtue of mechanical strength provided by a wall thickened with cellulose, hemicelluloses, and lignin, these cells can function as water-conducting vessels and provide structural support. Several transcription factor families regulate genes encoding wall synthesis enzymes. Certain NAC and MYB proteins directly bind upstream of structural genes and other transcription factors. The most detailed model of this regulatory network is established predominantly for a eudicot, Arabidopsis thaliana. In grasses, both the patterning and the composition of secondary cell walls are distinct from that of eudicots. …

Effects Of Arbuscular Mycorrhizal Fungal Infection And Common Mycelial Network Formation On Invasive Plant Competition, Rachael Elizabeth Workman

Dissertations and Theses

Understanding the biotic factors influencing invasive plant performance is essential for managing invaded land and preventing further exotic establishment and spread. I studied how competition between both conspecifics and native co-habitants and arbuscular mycorrhizal fungal (AMF) impacted the success of the invasive bunchgrass Brachypodium sylvaticumin early growth stages. I examined whether invasive plants performed and competed differently when grown in soil containing AMF from adjacent invaded and noninvaded ranges in order to determine the contribution of AMF to both monoculture stability and spread of the invasive to noninvaded territory. I also directly manipulated common mycelial network (CMN) formation by AMF …

Comparative Genome Analysis Between Agrostis Stolonifera And Members Of The Pooideae Subfamily Including Brachypodium Distachyon, Loreto P. Araneda

Masters Theses 1911 - February 2014

Understanding of grass genome structure and evolution has been significantly advanced through comparative genomics. The genomes of most cool-season forage and turf grasses, belonging to the Pooideae subfamily of the grasses, remain understudied. Creeping bentgrass (Agrostis stolonifera) is one of the most important cool-season turfgrasses due to its low mowing tolerance and aggressive growth habit. An RFLP genetic map of creeping bentgrass using 229 RFLP markers derived from cereal and creeping bentgrass EST-RFLP probes was constructed for a comparative genome analysis. This genetic map was compared with those of perennial ryegrass, oat, wheat, and rice. Large-scale chromosomal rearrangements …