Expression of rice gene OsMSR4 confers decreased ABA sensitivity and improved drought tolerance in Arabidopsis thaliana

The small heat shock proteins (sHSPs) are most prevalent in plants and are believed to play an important role in stress tolerance. Our microarray and qRT-PCR analyses of rice plants showed that the gene Oryza sativa Multi-Stress-Responsive 4 (OsMSR-4) is induced by heat, drought, and cold in different tissues at various developmental stages. OsMSR-4 encodes a Class III sHSP. Its expression in Arabidopsis thaliana conferred enhanced tolerance to drought accompanied by altered expression of other stress-related genes. Under drought conditions, levels of free proline were higher in transgenic plants than in the wild-type. The transgenics also showed decreased sensitivity to abscisic acid (ABA) during the seed germination and post-germination stages. Our study provides evidence that OsMSR4 has a key role in regulating plant responses to ABA and drought.