My lab is engaged in three areas of research in which undergraduate and graduate students participate: (1) plant adaptations to abiotic stresses, (2) plant responses to wounding and pathogen attack, and (3) biologically active metabolites in plants.
Plant Adaptations to Abiotic Stresses. Echinochloa phyllopogon (watergrass) is an invasive weed in rice paddies. Unlike most crop plants, E. phyllopogon can germinate in an anaerobic environment and the coleoptile grows for at least three weeks without oxygen. Since flooding can decrease crop yields by up to 20% annually, we are interested in discovering the molecular and physiological adaptations that permit E. phyllopogon to maintain active growth under conditions that lead to death in many crop plants. Currently, we are investigating the up-regulation of hexokinases and the subcellular localization of hexokinase isozymes in relation to flood tolerance.
Plant Responses to Wounding and Pathogen Attack. Plants have developed several defense mechanisms to deal with mechanical wounding and infections by bacteria and fungi. We are examining the induction of defense-related proteins induced in the cells and apoplast of leaves of Dioscorea bulbifera (air potato) that are mechanically wounded or challenged with bacterial or fungal pathogens. Preliminary studies indicate that salicylate may be an activator of the defense response in D. bulbifera and so we are also characterizing the defense response initiated by salicylate in the absence of bacterial or fungal elicitors.
Biologically Active Metabolites in Plants. We are continually collecting bulbils (a reproductive structure) from various populations of Dioscorea alata and D. bulbifera growing in northwest Florida and are propogating them in the greenhouse to screen for compounds that have herbicidal, antibacterial, or antifungal activity. Various tissues (leaves, stems, roots, bulbils) are extracted and the extracts separated by high-perfomance liquid chromatography (HPLC) to isolate terpenoid, steroidal, and flavanoid compounds that are tested in radish seed germination and Escherichia coli bioassays to screen for biologically active metabolites. We plan to expand this program to screen other plants native to the Florida Panhandle.