Spotlight 2010

Ling Zhu
Ling Zhu - Plant Biology Graduate Program

Ling Zhu

Graduate Student

Being sessile and photoautotrophic, plants have evolved multiple sensing mechanisms to optimize their growth and development in response to changes in environmental conditions. Among environmental factors, light is probably one of the most important, it controls almost every step in the life cycle of plants, such as seed germination, seedling establishment, flowering and reproduction. During these steps, light not only provides the energy source for photosynthesis, but also provides information about environmental changes. Plants sense red and far-red light through the phytochrome (phy) family of photoreceptors, of which Arabidopsis contains five members (phyAphyE). A current model proposes that phytochromes can regulate downstream gene expression through direct interaction with a group of basic helix-loop-helix (bHLH) transcription factors (Phytochrome Interacting Factors, PIFs) functioning negatively in phy-mediated light signaling pathways, triggering degradation of these negatively acting factors under light. However, the mechanisms of this degradation, as well as the direct target genes of PIFs, are still unknown.

My overall goal is to understand how the phy family perceives and transfers environmental light signals to modulate plant growth and development. We are using PIF1 as a model to investigate the mechanism of the light-induced degradation of these negative regulators in photomorphogenesis. Our lab has shown that PIF1 interacts with photoactivated forms of phyA and phyB and is rapidly degraded under both red and far-red light conditions, thus relieving negative regulation by PIF1 to promote seed germination and chlorophyll biosynthesis in light. My previous research included identification of PIF1 direct target genes and understanding the structure-function relationship of PIF1. Future work will focus on isolating factors responsible for PIF1 phosphorylation and degradation by using a genetic approach. Results from this project will help build a signaling network containing the photoreceptors, transcriptional factors and downstream factors that regulate the growth and development of plants. -Ling Zhu

Plant Biology images. (Photo credit: Dr. Z. Jeffrey Chen/University of Texas at Austin; Shutterstock images)