Salt Tolerance of Rice Is Enhanced by the Gene, Which Regulates Ascorbic Acid Synthesis and ROS Scavenging

Mining the key genes involved in the balance of rice salt tolerance is extremely important for developing salt-tolerant rice varieties. A library of mutants was screened under salinity conditions to identify putative salt stress-responsive genes. We identified a highly salt-sensitive mutant and used a map-based cloning approach to isolate the gene , which encodes mannose-1-phosphate guanylyltransferase. Under salt treatment, mutants have decreased ascorbic acid (AsA) content and increased reactive oxygen species (ROS) levels compared with the wild type (WT). Exogenous AsA restored the salt tolerance of plants, indicating that inhibition of AsA synthesis was an important factor in the salt sensitivity of the mutant. Functional complementation using the WT allele rescued the mutation, and transcription of was induced by salt stress. Vector was constructed containing the 1086 bp coding sequence of . Under salinity conditions, transgenic seedlings expressing had improved salt tolerance relative to WT, as demonstrated by better growth status, higher chlorophyll content, a lower level of Na, and a reduced Na/K ratio. Further investigation revealed that several senescence- and autophagy-related genes were expressed at lower levels in salt-stressed transgenic lines compared to WT. These results demonstrate the positive impact of on salt tolerance in rice through the regulation of AsA synthesis and ROS accumulation, and indicate that is a valuable target for genetic manipulation.