National Institute of Plant Genome Research
Digital India     
    Dr. Sudip Chattopadhyay
    FNA, FASc., FNASc., Ramanna Fellow
    Staff Scientist VI (Professor)
    Tel: 91-11-26741612,14,17 Ext - 175
    Direct: 26735175
    Fax: 91-011-26741658

 Research area
Light is one of the most important factors for plant growth and development, and the cross talk of light signaling pathways with other signaling cascades started to be unraveled. Depending on the presence or absence of light, Arabidopsis seedlings grow with two distinct developmental pathways: skotomorphogenesis or etiolation in the dark and photomorphogenesis or deetiolation in the light. Light is perceived by several photoreceptors: far red and red light by phytochromes (phyA to phyE) and blue and UV-A light by cryptochromes (cry1, cry2 and cry3). A significant progress has been achieved in determining the functional role of photoreceptors and the identification of early signaling components. However, the signal transduction from photoreceptors to downstream transcription factors remains unclear.
We have been investigating the Z-box specific transcription factors in light signaling pathways. Practically nothing was known about the Z-box and its regulation in plants when our laboratory started investigating the function of the Z-box and its associated transcription factors. We have been successful in demonstrating that Z-box binding factors (ZBFs) are present in plant and are intimately involved in plant growth and development. We have cloned several transcription factors by a ligand-binding screen using the Z-box as probe. Several such Z-box binding factors have been functionally characterized. For example, functional characterization of ZBF1/MYC2 (a bHLH transcription factor) reveals that ZBF1 acts as a negative regulator of photomorphogenic growth, however functions as a positive regulator of flowering time and lateral root formation. Furthermore, ZBF1 is the first transcription factor in plants that has been shown to act as a point of cross talk among light, ABA (abscisic acid) and JA (jasmonic acid) signaling pathways. We have investigated the genetic and molecular interrelations of ZBF1 with other light signaling components. The genome-wide transcriptional profiling (microarrays) of zbf1 cop1 double mutants further demonstrates that COP1 and ZBF1/MYC2 coordinately regulate the expression of a wide range of regulatory genes involved in light, multiple stresses and various metabolic pathways. Characterization of ZBF2/GBF1 (a bZIP transcription factor) at the molecular level reveals that ZBF2 differentially regulates plant growth and development and promotes root growth, flowering time and responsiveness to ABA. Further investigation has revealed that ZBF2/GBF1 protein is less abundant in the darkness, and is degraded by a proteasome-mediated pathway independent of COP1 and SPA1, the negative regulators of photomorphogenesis. COP1 physically interacts with ZBF2 and is rather required for the optimum accumulation of ZBF2 protein in light grown seedlings.
 Selected Publications
Mallappa C, Singh A, Ram H and Chattopadhyay S (2008) GBF1, a transcription factor of blue light signalling in Arabidopsis, is degraded in the dark by a proteasome-mediated pathway independent of Cop1 and SPA 1. Journal of Biological Chemistry 283: 35772-35782.
Kushwaha R, Singh A and Chattopadhyay S (2008) Calmodulin 7 plays an important roles as transcription regulator in Arabidopsis seedling development. Plant Cell 20: 1747-1759.
Bhatia S, Gangappa SN, Kuswaha R, Kundu S and Chattopadhyay S (2008) SHORT HYPOCOTYL IN WHITE LIGHT1, a Serine-Arginine-Aspartate-Rich protein in Arabidopsis, acts as a negative regulator of photomorphogenic growth. Plant Physiology 147: 169-178.
Bhatia S, Gangappa SN and Chattopadhyay S (2008) SHW1, a common regulator of abscisic acid (ABA) and light signaling pathways. Plant Signaling & Behavior 3: 1-3.
Mallappa C, Yadav V, Negi P and Chattopadhyay S (2006) A basic Leucine Zipper transcription factor, G-box-binding Factor 1, regulates blue light-mediated photomorphogenic growth in Arabidopsis. Journal of Biological Chemistry 281: 22190-22199.
Yadav V, Chandrashekara M, Sreeramaiah NG, Bhatia S and Chattopadhyay S (2005) A basic helix-loop- helix transcription factor in Arabidopsis, MYC2, acts as a repressor of blue light-mediate photomorphogenic growth. Plant Cell 17: 1953-1966.
Hettiarachchi GHCM, Yadav V, Reddy MK and Chattopadhyay S (2005) Regulation of TOP2 by various abiotic stresses including cold and salinity in pea and transgenic tobacco plants. Plant Cell Physiol. 46: 1154-1160.
Hettiarachchi GHCM, Yadav V, Reddy MK, Chattopadhyay S and Sopory SK (2003) Light mediated regulation defines a minimal promoter region of TOP2. Nucleic Acids Research 31: 5256-5265.
Yadav V, Kundu S, Chattopadhyay D, Negi P, Wei N, Deng XW and Chattopadhyay S (2002). Light regulated modulation of Z-box containing promoters by photoreceptor and downstream regulatory components, COP1 and HY5, in Arabidopsis thaliana. Plant Journal 31: 741-753.