Poster: Regulation of gene expression

Abs # 762: Involvement of Phytochrome, G-proteins, calcium, calmodulin, phosphorylation status and tagetitoxin-sensitive RNA polymerase in light-regulated expression of plastid genes (psbA, psaA and rbcL) in rice (Oryza sativa L.)

Presenter:	Dhingra, Amit , adhingra@mail.ucf.edu
Authors	Dhingra, Amit  (A) (B)  Khurana, Jitendra P (A)   Tyagi, Akhilesh K (A)
Affiliations:	(A): Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India (B): Department of Molecular Biology and Microbiology, University of Central Florida
Web Site:	http://www.iirgs.org

The regulation of chloroplast gene expression by light involves multiple signaling components. The light signal is perceived by a photoreceptor and is relayed downstream by employing established secondary messengers that eventually produce a tangible effect on the expression of a given gene. Using rice as a model monocot system, we investigated the primary step of light perception and demonstrated the involvement of phytochrome in regulation of expression of photosynthesis related plastid genes psaA, psbA and rbcL, representing photosystem I, photosystem II and a stromal protein, via classical Red/Far-Red reversibility response. Steady-state transcript level analysis of the same genes in 5-day-old etiolated rice seedlings vacuum infiltrated with agonists and antagonists of known signaling intermediates have indicated the involvement of heterotrimeric GTP-binding proteins, cyclic GMP, calcium, calmodulin and phosphorylation status in regulating plastid gene expression. In addition, the light-regulated expression of photosynthesis related genes was adversely affected by tagetitoxin, a specific inhibitor of plastid-encoded RNA polymerase (PEP). These results indicate the involvement of various signaling components in transduction of light signal that probably also recruits PEP to regulate plastid gene expression.