Plant & Animal Genomes XVI Conference Plant & Animal Genomes XVI ConferenceJanuary 12-16, 2008
Town & Country Convention Center
San Diego, CA
Fleshy fruit development is an important component of yield and quality for a wide range of horticultural and specialty crops. Most fruit genomic studies have emphasized late development (e.g. ripening and fruit quality), but for cucumbers, which are harvested immature, early fruit development is most important. In this project we have monitored cucumber fruit development from 0 - 32d to provide a catalog of morphological and developmental benchmarks to anchor observations of gene expression patterns with fruit developmental processes. Young cucumber fruits (0-16d) show marked changes in fruit size, cell size, surface wax, chlorophyll content and patterns, wart formation, trichome development, and placenta and seed development. These changes underscore the activity of dynamic developmental processes occurring during early fruit growth. Young cucumber fruit also undergo a distinct transition at 10-12 d that confers resistance to the important oomycete pathogen, Phytophthora capsici. This loss of susceptibility, which coincides with the end of the period of rapid fruit elongation, also occurs as a developmental gradient along the length of the fruit, was observed in both the greenhouse and field, for several cucumber cultivars, and for several other cucurbit crops. The difference in susceptibility in cucumber can be localized to the upper 1-2 mm of the fruit surface and is not associated with seed development as parthenocarpic fruit also showed increased resistance with age. We are undertaking a 454-pyrosequencing project to analyze gene expression from whole fruit, fruit peel, and mesocarp tissue of different ages in reference to the developmental benchmarks.