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PLANTS, PLANT PATHOGENS, AND MICROGRAVITY- A DEADLY TRIO. J.E. Leach. Department of Plant Pathology, Kansas State University, Manhattan. 

Plants grown in spaceflight conditions are more susceptible to colonization by plant pathogens. The underlying causes for this enhanced susceptibility are not known. Possible causes are that the formation of structural barriers or the activation of plant defense response components are impaired in spaceflight conditions. Either mechanism would result from altered gene expression of the plant. Because of the tools available, past studies focused on limited physiological responses or biochemical pathways. With recent advances in genomics research, new tools, including microarray technologies, are available to examine the global impact of growth in the spacecraft on the plant's gene expression profile. In ground-based studies, we have developed cDNA subtraction libraries of rice that are enriched for genes induced during pathogen infection and the defense response. Arrays of these genes are being used to dissect plant defense response pathways in a model system involving wild-type rice plants and lesion mimic mutants. The lesion mimic mutants are ideal experimental tools because they erratically develop defense response-like lesions in the absence of pathogens. The gene expression profiles from these ground-based studies will provide the molecular basis for understanding the biochemical and physiological impacts of spaceflight on plant growth, development and disease defense responses. This, in turn, will allow development of strategies to manage plant disease for life in the space environment