Characterization and Fine Mapping of the Early Senescence Mutant esls in Rice

A novel rice mutant, EARLY SENESCENCE LEAF SHEATH (ESLS), was generated from the Koshihikari cultivar by EMS treatment. This mutant exhibited spontaneous lesions mimic spots on the leaf sheath in the absence of the pathogen attack from the early seedling stage. Subsequently the leaves of the esls plants turned yellow and exhibited more severe symptoms during reproductive and ripening stages. SPAD value, and soluble protein content of esls flag leaves decreased steeply after the heading stage. The growth vigor was much weaker and slower in esls plants. Moreover the yield-related agronomic traits such as spikelet number per panicle, seed setting rate, and 1,000-grain weight were significantly reduced in esls plants. Genetic analysis showed the senescence was controlled by a single recessive nuclear gene. Using F₂ population of esls/M.23, ESLS was mapped to a 66-kb region between InDel marker 147-1 and147-2 on the long arm of chromosome 7. These results will facilitate the positional cloning and functional studies of the ESLS gene.