Molecular cloning of a dehydration-responsive protein gene (MRD22) from mulberry, and determination of abiotic stress patterns of MRD22 gene expression.

A full-length cDNA sequence coding for Dehydration-responsive protein gene of mulberry tree, which we designated was MRD22 (GenBank accession number: JQ804833) was cloned based on mulberry expressed sequence tags (ESTs). MRD22 is 1503 bp long, contains a 334 bp 5'-UTR (untranslated region) and a 563 bp 3'-UTR, encodes 201 amino acids with a predicted molecular weight of 54.28 kDa and an isoelectric point of 9.35. Phylogenetic analysis based on MRD22 sequences from different species showed that mulberry has close relationship with Populus trichocarpa, Ricinus communis, Camellia sinensis, Gossypium hirsutum, Gossypium barbadense and so on. The expression level of the MRD22 gene under conditions of drought, low temperature and salt stresses was quantified by qRT-PCR. The results show that the expression level changed significantly under the stress conditions compared to the normal growth environment. It helps us to get a better understanding of the molecular basis for signal transduction mechanisms underlying the stress response in mulberry.