Overexpression of a Rice Monosaccharide Transporter Gene (OsMST6) Confers Enhanced Tolerance to Drought and Salinity Stress in Arabidopsis thaliana

Monosaccharide transporter (MSTs) is a large family of integral membrane proteins that plays a crucial role in cell-to-cell and long-distance distribution of sugars throughout the plant. It has long been regarded as one of the most essential components in a myriad of plant physiological functions such as carbohydrate partitioning, sugar signaling, and environmental stress response. In the present study, an in vivo functional analysis of a rice monosaccharide transporter gene, namely OsMST6, has been conducted using a transgenic approach to understand its role in plant responses to abiotic stress. Physiological traits analysis indicated that the transgenic lines had a relatively lower water loss rate, higher relative water content (1.3-2.2-fold), increased cell membrane stability (1.5-2-fold), and higher total soluble sugar content (2.8-3.5-fold) compared to the parental lines. Furthermore, the overexpression of OsMST6 was also found to enhance both drought and salt tolerance in transgenic Arabidopsis thaliana. Taken together, these results suggested that OsMST6 may be involved in the adaptation of rice plant to water stress by maintaining the water status of plant cells. This study provides insight into the function of OsMST6, which may have potential application in the generation of transgenic abiotic stress-tolerant plants.