中文摘要：

叶片早衰直接影响作物产量和品质，鉴定早衰突变体、图位克隆调控基因对于研究植物衰老机制具有重要的意义。以甲基磺酸乙酯诱变水稻籼型恢复系缙恢10号，获得-个早衰突变体esl5（earlysenescentleafmutant5），本文对其进行了形态鉴定、细胞学观察、理化分析和基因定位等研究。结果表明，与野生型相比，esl5的苗期叶片正常，分蘖期呈黄绿色，孕穗期开始叶片中上部逐渐黄化衰老 衰老部位的细胞结构异常，细胞膜降解，叶绿体基质片层疏松、排列不规则，光合色素含量和光合速率极显著下降。此外，esl5的·OH和H202含量极显著升高，SOD和CAT的活性则极显著降低。与野生型相比，esl5的生育期延长20d左右，千粒重显著增加，穗粒数、实粒数和结实率则显著降低。esl5突变性状受1对隐性核基因调控，精细定位在第3染色体Indel标记Indel03-1和Indel03-2之间83．4kb的物理范围内，包含11个注释基因，这为ESL5的克隆和功能研究奠定了基础，也有利于水稻品种的遗传改良。

英文摘要：

Premature senility directly influences crop yield and quality in the production. Therefore, it is crucial to identify early senescent leaf mutants and then clone genes associated with senescence by map-based strategy, which is significant in the research of senescence mechanism. An early senescent leaf mutant esl5 has been discovered from the progeny of indica restorer line Jin huil0 with seeds treated by ethylmethane sulfonate, this paper performed the studies on its morphological identification, cytological observation, physiological analysis and gene mapping. The results showed that the esl5 demonstrated normal phenotype at the seedling stage, displayed yellow green color at the tillering stage, and appeared yellow and senescent leaf blades at booting stage. Cell structure of the esl5 was badly influenced, showing destroyed cell membranes, loose and irregular stroma lamella in the section of senescent leaves. Chlorophyll content and photosynthetic rate of the esl5 were significantly lower than those of the wild type. Besides of the lower activities of SOD and CAT, the higher contents of ＂OH and H202 were detected in the esl5 than in the wild type. The growth period of esl5 delayed 20 days, grain number per panicle, filled-seed number and seed setting rate decreased significantly, but 1000-seed weight increased significantly at compared with the wild type. Genetic analysis suggested that the mutant trait was controlled by a recessive nuclear gene, and the ESL5 was fine mapped on chromosome 3 between Indel markers Indel03-1 and Inde103-2 with 83.4 kb physical distance, containing 11 annotated genes. These results provide a foundation for the cloning of ESL5 by map-based strategy, which is essential in the research of senescence mechanism as well as mo- lecular breeding in Oryza sativa.