Uncovering HEMERA-mediated Phytochrome Signaling Mechanisms in Arabidopsis

Duke University, Durham NC

Investigators

Abstract

Light is one of the most influential environmental cues regulating almost every facet of plant growth and development, from seed germination, chloroplast differentiation and photosynthesis, to flowering. Although it has been well known that phytochromes are red and far-red light receptors mediating most of the light responses, early signaling mechanisms linking light activation of phytochromes and the resulting morphological responses remain elusive. The PI developed a novel genetic screen specifically targeted at signaling components involved in one of the earliest light responses, the movement of phytochromes within the cell. This unique genetic screen identified a novel component for phytochrome signaling, HEMERA (HMR), in the plant model species Arabidopsis. Interestingly, HMR is required for multiple early phytochrome signaling events and is the first phytochrome-signaling component essential for the development of chloroplasts from their pro-plastid precursors (chloroplast differentiation). The research is aimed at uncovering HMR-mediated signaling mechanisms leading to light-dependent chloroplast differentiation. The specific aims are: (1) To determine how phytochromes regulate HMR; (2) To determine the location of HMR in cells in relationship to light signaling and chloroplast differentiation; (3) To identify and characterize components downstream of HMR by looking for mutations that restore normal traits in a plant where HMI is otherwise not functional. The outcomes of this project could contribute significantly to our basic knowledge of how plant development is regulated by environmental cues. A better understanding of this process will have profound implications in increasing yield and enhancing agronomically beneficial traits in crops. In particular, the elucidation of how chloroplast differentiation is initiated by light will ultimately provide the knowledge to facilitate scientists to improve photosynthetic capacity in biofuel crops. In addition, the project will provide excellent training in molecular genetic approaches for postdoctoral fellows, graduate students, and undergraduate students.