Molecular cloning of HSP17 gene (sHSP) and their differential expression under exogenous putrescine and heat shock in wheat (Triticum aestivum)
Polyamines (PAs) are low molecular weight ubiquitous nitrogenous compounds found in all the living organisms, which have been implicated in the expression of various stress-proteins against the abiotic stresses. Small heat shock proteins (sHSPs) are of particular importance in the thermotolerance and have been reported to act as molecular chaperones preventing denaturation or aggregation of the target proteins. Here, we report cloning of a small HSP of ~573 bp from C-306 cultivar of wheat (Triticum aestivum L), having open reading frame of 162 amino acids. In silico analysis showed the presence of an alpha crystalline domain (ACD), the signature domain for small HSPs. Consensus localization prediction (ConLoc) provides 98% consensus prediction of HSP17 in the nucleus. Quantitative real time polymerase chain reaction (qRT-PCR) analysis of HSP17 gene showed maximum (34 fold) transcript in C-306 and minimum (1.5 fold) in HD2329 cultivars of wheat in response to differential treatment of putrescine (1.5 to 2.5 mM + heat shock of 42°C for 2 h). Putrescine seems to enhance the transcript levels against the heat shock much more pronounced in thermotolerant than in the susceptible cultivars.
Key words: Triticum aestivum, heat stress, small heat shock protein, putrescine, HSP17, polyamine, domain, cloning.