Projects

Regulatory Specificity of R2R3 MYB Transcription Factors: The Control of Branched Flavonoid Pathways in Maize As a Case Study 

Much progress has been made in elucidating the mechanisms of transcriptional regulation in eukaryotes. It is becoming clear that the regulatory specificity of transcription factors (TFs) is not given only by their interaction with conserved DNA-sequence motifs in the promoters of the genes that they control, but also by the interactions with other factors, which may or may not bind the target promoters. This strategy, also known as combinatorial transcriptional control, has been best studied in plants in studies focusing on the regulation of  flavonoid biosynthesis in maize. read more...

Control of Lignin and General Phenylpropanoid Pathway in Maize 

Grasses, including maize, are a major source of agricultural biomass, offering significant opportunities for increasing renewable fuel production. Efficient biofuel production is influenced by lignin content which can significantly reduce extractable sugar content. To explore the possibility of altering lignin, we are investigating regulators of the maize phenylpropanoid pathway. The maize R2R3-MYB P1 controls accumulation of phlobaphenes in seed coats and biosynthesis of insecticidal C-glycosyl flavones in silks. Few steps of these pathways are known, and only the A1 gene encoding dihydroflavonol reductase is confirmed as immediate target of P1. To establish the overall regulatory function of P1, we performed a genome-wide analysis combining RNA-Seq and ChIP-Seq using two maize varieties varying highly in their P1 expression. Computational analysis of the data revealed that P1 particularly plays a role in flavonoid biosynthesis, and to a lesser extent in other branches of the phenylpropanoid pathway. read more...

The Maize Transcription Factor ORFeome Collection

Our lab is currently working towards generating an ORF collection of all maize transcriptional regulators, the Maize TFome. To identify new phenolic regulators, we will investigate the ability of these to activate in yeast a collection of +150 promoters of the genes corresponding to all known phenolic enzymes and regulators. The first release of the Maize TFome collection, comprised of 1903 ORFs, will be released through the ABRC at OSU. Data generated through the yeast assays, as well as information on how to order all or part of the collection will be housed at GRASSIUS.

Regulatory Networks Participating in Trichome Development

Position-dependent cell fate determination and pattern formation are unique aspects of the development of plant structures. The establishment of single-celled leaf hairs (trichomes) from pluripotent epidermal (protodermal) cells in Arabidopsis thaliana provides a powerful system to determine the genetic/regulatory networks and positional signals involved in cell fate determination. read more....

Arabidopsis Stomatal Development

Stomata, as the gate for gas exchange and water vapor, are essential for plant survival. In recent years, more and more studies focused on stomata development. Many genes were identified that are involved in controlling different stages during stomata development, such as TMM, YODA, MUTE, ER, FAMA, FLP and MYB88. Our interest focuses on the function of FLP/AtMYB88 in stomata development, research that is being carried in collaboration with Dr. Fred Sack. Based on the clustered guard cells phenotype in the flp mutant (four lips), FLP is suggested to participate in the transition of division to differentiation of guard cells. Uncovering the molecular function of FLP will lead to better understand how FLP control stomata development. Our biochemical and genetic data showed that FLP, as a MYB protein, is a transcription factor with a distinct DNA-binding specificity. By using microarray and ChIP-chip approaches, we have started to identify the direct targets of FLP during stomata development, uncovering unique mechanisms by which this atypical R2R3-MYB transcription factor regulates stomatal development. read more....

Establishing Regulatory Networks in Arabidopsis

Gene regulatory information is encoded in the promoter regions formed by cis-regulatory elements that bind specific transcription factors (TFs). Hence, establishing the architecture of plant promoters is fundamental to understanding gene expression. AGRIS (http://arabidopsis.med.ohio-state.edu) is an information resource of Arabidopsis promoter sequences, TFs, and their target genes. read more....

Phytochemical Trafficking in Arabidopsis Cells 

Plants produce a very large number of specialized compounds that must be transported from their site of synthesis to the sites of storage or disposal. Anthocyanin accumulation has provided a powerful system to elucidate the molecular and cellular mechanisms associated with the intracellular trafficking of phytochemicals. We recently showed (Poustka et al; 2007) that Arabidopsis anthocyanin are transported to the vacuole trough vesicle-like structures shared with components of the secretory pathway and in a Golgi-independent manner. We hypothesis that two mechanisms for anthocyanin cellular transport, one involving transporters and one involving vesicles, coexist in a plant cell or might be both part of a common trafficking pathway. read more....

Phlobaphene Biosynthesis in Maize

In maize, at least two flavonoid biosynthetic pathways have been characterized that are regulated independently. One pathway results in 3-hydroxy flavonoids such as >anthocyanins purple pigment, whereas the other pathway produces 3-deoxy flavonoids such as the phlobaphene red pigment accumulated in kernel pericarp, silks and cob. read more....

Mathematical And Computational Studies of Small Gene Regulatory Network Behavior

We are interested in using mathematical modeling and simulation to gain insight into the behavior of small gene regulatory network behavior, in particular those that may be involved in developmental processes such as cell fate determination. Previous work in our lab has focused on using chemical reaction network theory to identify model networks that have the capacity for bistability. Results have been used to discover possible switch-like circuits in yeast, and have highlighted the potential usefulness of parameter-free modeling for the characterization of complex networks, the study of network evolution, and the development of novel synthetic biological switches. read more...

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