The effect of drought and salinity on the expressional levels of sucrose transporters in rice (Oryza sativa Nipponbare) cultivar plants

Rice, like other plants, contains a number of sucrose transporter genes. However knowledge of their expression and regulation during environmental stress conditions is limited. Using expressional analysis, the role of sucrose transporter genes was examined during drought and salinity stress conditions in 3-week-old rice (Orzya sativa L. cv Nipponbare) plants, over a time-course of 1 to 10 days of stress treatment. Among the 5 rice sucrose transporter genes identified, only OsSUT2 was up-regulated during drought and salinity treatments. OsSUT1, OsSUT4 and OsSUT5 were only expressed at low levels, while OsSUT3 showed no significant expression. The transport of sucrose is essential for long distance sucrose transport necessary to meet the cellular energy demands and also for osmoprotectant activities during drought and salinity stresses. It therefore indicates that OsSUT2, which facilitates transport of sucrose from photosynthetic cells, is essential for rice plants to cope with drought and salinity stresses, and cultivars with higher expression should be able to tolerate these environmental stresses better than those with lower expression.