Environmental factors such as light and temperature play a major role in regulating plant development and physiology, and have a significant impact on agricultural production. This proposal concerns the molecular and genetic basis for the regulation of flowering time by daylength, or photoperiod, focusing on the model plant Arabidopsis thaliana. Although recent progress has significantly increased the understanding of photoperiodic regulation of flowering, it is apparent that a number of key components of this signal transduction pathway are still unknown.
Mutations at the EARLY FLOWERING 3 locus offer a unique inroad to the interactions between biological clocks and complex developmental processes such as floral initiation and light regulation. New genes that influence photoperiodic flowering will be identified and analyzed by isolating modifiers of the elf3 mutant phenotype using a genetic screen. Modifiers of the strong reduced function elf3-1 allele that restore photoperiod sensitivity (pse mutants) are likely to identify proteins that function downstream of ELF3 in the photoperiodic pathway. A number of mutations that restore photoperiod sensitivity in the absence of ELF3 function have already been identified. New loci identified in this modifier screen will be mapped using PCR-based molecular markers, and positional or candidate gene cloning will be undertaken for at least two modifier loci. In addition, this project aims to understand the links between photoperiodic regulation of flowering, photomorphogenesis, and circadian regulation. Phenotypic analysis of pse elf3-1 double mutants will test the hypothesis that these three processes are genetically separable.
The discovery of new genes that influence photoperiodic flowering time will add to the repertoire of loci that are known to affect the transition to reproductive growth and might be manipulated to increase agricultural yield. An integral component of this project is the training and mentoring of undergraduate students. Their involvement in this research program will foster the development of laboratory skills and intellectual abilities that will enrich their lives and enable them to contribute to further progress in science.
