Cloning and functional characterization of the HbSYR1 gene encoding a syntaxin-related protein in Tibetan hulless barley (Hordeum vulgare L. var. nudum HK. f.).

Tibetan barley is a staple food for the natives of Qinghai-Tibet Plateau. Drought causes a reduction in barley production. In this study, the full-length cDNA of a gene encoding a syntaxin-associated protein was cloned from the leaves of a drought-resistant variety of barley, "Himalaya 10"; its expression was evaluated during drought stress and rehydration via real-time PCR. The cloned HbSYR1 cDNA sequence was 1300 bp in length, and included an 840-bp open reading frame that encoded 279 amino acids. Sequence analysis predicted the molecular weight of the encoded protein to be 42.08 kDa, with an isoelectric point of 4.98. ScanProsite analysis showed that the HbSYR1 protein contained a SNARE family characteristic motif, five casein kinase II phosphorylation sites, two N-glycosylation sites, four protein kinase C phosphorylation sites, and two N-myristoylation sites. The TMHMM prediction program indicated that the protein does not contain a transmembrane transfer ribbon. According to the SignalP 3.0 server, this protein does not contain a signal peptide, and is not a secretory protein. Instead, this protein was suggested to be localized in the cytoplasm, as predicted by the protein subcellular localization prediction tool (PSORT). Our results indicated that HbSYR was induced by drought stress and rehydration, and was determined to be a key gene for drought resistance and water retention in barley.