The Role Of Red-Light Signaling In Plant Gravitropic Response

Plants modify their growth and development in response to their environment. Gravity plays an important role in development by directing root and shoot growth. Unlike wild type tomato plants, lazy-2 (lz-2) mutants display reverse gravitropism. This response is red-light dependent and is hypothesized to be dependent one of the phytochromes (Gaiser and Lomax 1993), an important family of red-light photoreceptors. Using RNA interference (RNAi), we will transcriptionally inactivating one of the known five tomato phytochrome genes (PHYTOCHROME F) to determine its role in the development of the plant’s overall phenotype and the interaction of light. In addition, gravitropic growth is known to be mediated by the plant hormone auxin and work from several groups has shown a direct connection between red-light signaling and auxin. Using DR5:GUS, we will visualize difference in auxin localization in both wild-type and lz-2 seedlings to dissect the role of red-light and auxin in mediating reverse gravitropism. Together, this work will further our understanding of how plants translate information from their light environment to mediate their growth and development. A plant’s architecture determines both the vigor of the plant itself as well as the amount and quality of the plant’s harvestable biomass. Tomato (Solanum lycopersicon) serves both as a primary model for fruit development as well as an agriculturally important plant. The recent publication of its genome sequence as well as the availability of genetic mutants makes it well-suited for the study of developmental processes.