9420124 Pierce Plants accumulate phytoalexins as one of several active- defense mechanisms. These infection-induced, low molecular weight, antimicrobial compounds have been shown in several host/pathogen systems to accumulate in planta to concentrations sufficient to account for pathogen inhibition, judging from in vitro bioassays. The question remains whether they are essential for resistance. If plants rely on phytoalexins for a significant fraction of their resistance, then genes controlling phytoalexin synthesis are worthy targets for genetic manipulation with potential for crop improvement. This project will test the necessity of phytoalexins for resistance to bacterial blight in cotton by producing transgenic plants with altered ability to accumulate phytoalexins and evaluating their resistance following inoculation with Xanthomonas campestris pv. malvacearum. By manipulating phytoalexin accumulation apart from other aspects of the hypersensitive resistant response, the project will provide a clearer understanding of how plants need to react in order to successfully fight disease.
