Identification and Gene Mapping of an early senescence leaf 4 Mutant of Rice

ABSTRACT An early senescence leaf 4 (esl4) mutant of rice (Oryza sativa L.) displayed yellowing followed by severe chlorosis of the leaf apex and margin from the late jointing stage to maturity. The content of photosynthetic pigments in the mutant was significantly lower than in wild‐type plants, and abnormalities in cell structure were detected in the mutant leaf blade. Stomatal conductance and rates of photosynthesis and transpiration were lower in esl4 than in wild‐type plants. Furthermore, compared with the wild‐type, the activities of superoxide dismutase and catalase were significantly lower in esl4, whereas peroxidase activity was significantly higher in esl4. Genetic analysis indicated that the early senescence of esl4 was controlled by a recessive nuclear gene. A population of 879 F2 mutants was used to fine‐map the ESL4 gene to chromosome 4 between the insertion and deletion primers S4–42 and S4–67. This 63‐kb stretch encodes 12 uncharacterized open reading frames. Quantitative real‐time polymerase chain reaction analysis (qRT‐PCR) revealed that levels of SGR transcripts were considerably more abundant in esl4 than in wild‐type. These results provide a foundation for map‐based cloning and functional analysis of the ESL4 gene.