Identification, characterization and expression of drought related alpha-crystalline heat shock protein gene (GHSP26) from desi cotton

In response to water deficit stress, plants show quantitative and qualitative differences in gene expression. By using differential display and RACE (rapid amplification of cDNA ends) polymerase chain reaction (PCR) techniques an alpha crystal line-type small heat shock protein gene (GHSP26) was isolated and characterized from Gossypium arboreum L. Alignments of 1108 bp genomic and 1026 bp cDNA sequences revealed that the GHSP26 gene comprises a single open reading frame of 230 amino acids and it contains a single intron. The gene product contains the highly conserved alpha crystalline region, spanning amino acid residues 133 to 217 and a Met-rich region from 94 to 117aa at the N terminus. Predicted amino acid sequence shares 65%, 63%, 59%, 58%, 56%, 55%, 53%, and 22% identities with Petunia hybrida, Nicotiana tabacum, Arabidopsis thaliana, Zea mays, Agrostis stolonifera, Triticum aestivum, Oryza sative, and Nitrosococcus oceani, respectively. Expression profile of the gene was studied from leaf, stem, and root tissues, through reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative real-time RT-PCR analysis. The results indicated that the gene was expressed in all tissues tested in both fully hydrated and dehydrated plants. However, the gene was 100-fold more abundant in dehydrated leaves, while only two-fold abundant in stressed root and stem as compared to control tissues.