INVESTIGATOR: Mockler, Todd C.; Hazen, Samuel P.
INSTITUTION: Donald Danforth Plant Science Center
NON-TECHNICAL SUMMARY: Plant growth and development, including stem elongation, flowering time, and biomass yield, are affected by the light environment. The goal of the proposed research is to use genomics and genetics in the model grass system Brachypodium distachyon to identify genes involved in light perception and signaling that will increase the yield and improve the composition of bioenergy grasses. Identification of genes capable of modifying growth characteristics of grasses, in particular increasing biomass accumulation, by modulating light perception and signaling will provide valuable candidates for manipulation in bioenergy grass crops through targeted breeding or engineering efforts.
OBJECTIVES: 1. Misexpress 180 candidate Brachypodium phytochrome signaling genes, including transcription factors implicated in regulation of gene expression by red and far-red light. 2. Screen and score the misexpression lines for morphological and developmental phenotypes, dry biomass accumulation, and seed yield. 3. Characterize lines exhibiting clear differences in growth and/or growth rates using a Clostridium phytofermentans based bioassay to measure the impact of manipulating the expression of phytochrome signaling genes on cell wall quality, as measured by digestibility. 4. Interrogate direct interactions between 100 candidate phytochrome signaling transcription factors and 20 target promoters using a high-throughput yeast one-hybrid system.
APPROACH: This project will screen a collection of promising phytochrome signaling gene candidates for functions in yield and composition traits and define the transcriptional regulatory networks that modulate these traits. As a first step the expression of genes predicted to function in Brachypodium phytochrome signaling will be systematically manipulated by overexpression and knockdown approaches. The resulting collection of mutant Brachypodium lines will then be screened for phenotypes relating to morphology, stature, biomass accumulation, and cell wall composition. In parallel direct interactions between candidate phytochrome signaling transcription factors and their target promoters will be interrogated using a high-throughput yeast one-hybrid system in order to further elucidate the mechanisms underlying the gene regulatory networks that control light-regulated biomass yield.
Name: Mockler, T.
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