摘要 : Plants respond to heat stress by enhancing the expression of genes encoding heat shock protein (HSPs) genes through activation of heat shock factors (HSFs) which interact with heat shock elements present in the promoter of HSP gen... 展开 Plants respond to heat stress by enhancing the expression of genes encoding heat shock protein (HSPs) genes through activation of heat shock factors (HSFs) which interact with heat shock elements present in the promoter of HSP genes. Plant HSFs have been divided into three conserved classes viz A, B and C. In the present study, a detailed analysis has been done of all rice HSFs, along with their spliced variants. Their chromosomal localization reveals that six HSFs are segmentally duplicated and four pairs of these segmentally duplicated HSF encoding genes show pseudo-functionalization. Expression profiling through microarray and quantitative real-time PCR showed that eight <i>OsHsfs</i> express at a higher level during seed development, while six HSFs are up-regulated in all the abiotic stresses studied. The expression of <i>OsHsfA2a</i> gene in particular was greatly stimulated by heat stress in both root and shoot tissues and also during panicle and seed development. <i>OsHsfA3</i> was found more responsive to cold and drought stress, while <i>OsHsfA7</i> and <i>OsHsfA9</i> showed developing seed-specific expression. This study also revealed that spliced variants generally accumulated at a higher level in all the tissues examined. Different hormones/elicitors like ABA, brassinosteroids and salicylic acid also alter <i>OsHsf</i> gene expression. Calcium in combination with heat stress elevated further the level of HSF transcripts. Expression analysis by both microarray and real-time RT-PCR revealed a unique stable constitutive expression of <i>OsHsfA1</i> across all the tissues and stresses. A detailed in silico analysis involving identification of unidentified domains has been done by MEME-motif tool in their full-length proteins as well as in DNA-binding domains. Analysis of 1 kb putative promoter region revealed presence of tissue-specific, abiotic stress and hormone-related <i>cis</i>-acting elements, correlating with expression under stress conditions. 收起