Molecular Aspects of Heat Stress Response of Rice Plants

Molecular Aspects of the Heat Stress Response of Rice Plants

by Prof Anil Grover - External examiner- Department of Plant Molecular Biology, University of Delhi South Campus Benito Juarez Road, DhaulaKuan, New Delhi‐110021, India (email:anil.anilgrover@gmail.com)

Rice (Oryzasativa L.) is the most important food crop. The rice transcriptional profile is significantly modulated by heat stress: the enrichment of GO terms protein kinase activity/ protein serine kinase activity, response to heat and reactive oxygen species in up‐regulated genes signifies the role of signal transduction events and reactive oxygen species during early heat stress (Mittal et al. 2012a,b, Sarkar et al. 2014). The proteins associated with chaperones and protein degradation machineries of the cell are stimulated as one of the early steps in minimizing damages to other proteins. Genome‐wide biology of rice Hsp20, Hsp40, Hsp70 and Hsp100 as well as heat shock factors has been unearthed from our studies (Sarkar et al. 2009, Singh et al. 2010, Sarkar et al. 2013a, Sarkar et al.2013b). Rice contains three ClpB/Hsp100 proteins localized to different cellular compartments: cytoplasm/nucleus (OsClpB‐c), mitochondria (OsClpB‐m) and chloroplast (OsClpB‐p) (Mishra and Grover 2015). OsClpB‐c (Os05g44340), OsClpB‐m (Os02g08490) and OsClpB‐p (Os03g31300) proteins are able to complement the thermo‐sensitive phenotype of yeast hsp100 mutant (ΔSchsp104) (Singh and Grover 2010, Singh et al. 2010). Arabidopsis Hot1‐3 is a null mutant for ClpB‐c gene, and is highly thermo‐sensitive both at the seed and seedling levels (Hong and Vierling 2000). We are interested to analyse the strategies of expression of Hsp100 forms which can possibly result into high temperature resistant crops. We have documented that OsHsfA2c (a) has rapid transcript induction under high temperature stress, (b) possesses transactivation activity, (c) forms homo‐oligomeric configuration, (d) regulates expression from OsClpB‐c promoter in heat shock element (HSE)‐dependent manner and (e) interacts with OsClpB‐c and OsHsfB4b proteins (Mittal et al. 2009, Mittal et al. 2011, Singh et al. 2012). We infer that supra‐complexes, involving several OsHsfs, regulate Hsp promoters under high temperature stress in rice.