<i<pOsHAK1:OsSUT1</i< Promotes Sugar Transport and Enhances Drought Tolerance in Rice

Plant cells accumulate osmotic substances (e.g., sugar) to protect cell components and maintain osmotic balance under drought stress conditions. Previous studies found that <i<pOsHAK1:OsFLN2</i< promotes sugar metabolism and improves the drought tolerance of rice plants under drought str...
Ausführliche Beschreibung

Plant cells accumulate osmotic substances (e.g., sugar) to protect cell components and maintain osmotic balance under drought stress conditions. Previous studies found that <i<pOsHAK1:OsFLN2</i< promotes sugar metabolism and improves the drought tolerance of rice plants under drought stress. This study further evaluated the effect of the ectopic expression of the <i<OsSUT1</i< gene driven by the <i<OsHAK1</i< promoter on the sugar transport and drought tolerance of rice. The results showed that the net photosynthetic rate and sucrose phosphate synthase activity of plants expressing the <i<OsSUT1</i< gene were not significantly different from those of wild-type (WT) rice plants under drought conditions. However, the sucrose transport rate in the phloem increased in the transgenic plants, and the sucrose contents were significantly lower in the leaves but significantly higher in the roots of transgenic plants than those in WT plants. The <i<pOsHAK1:OsSUT1</i< and <i<pOsHAK1:OsFLN2</i< transgenic lines had similar rates of long-distance sucrose transport and drought tolerance, which were higher than those of the WT plants. The relative water content of the transgenic plants was higher, while their water loss rate, hydrogen peroxide (H<sub<2</sub<O<sub<2</sub<), and malondialdehyde (MDA) contents were lower than those of the WT plants. The stress-responsive gene <i<OsbZIP23</i< and the antioxidant-related gene <i<OsCATB</i< were significantly upregulated in the drought-treated transgenic lines, while the senescence indicator gene <i<SGR</i< and the stress-responsive gene <i<OsNAC2</i< were down-regulated compared to WT plants. These results showed that promoting the long-distance sugar transport through the expression of <i<pOsHAK1:OsSUT1</i< could produce an improved drought tolerance effect similar to that of <i<pOsHAK1:OsFLN2,</i< providing an effective way to improve the drought tolerance of cereal crops at the seedling stage. Ausführliche Beschreibung