中文摘要：

鉴定和克隆水稻穗顶部退化突变体新基因,对研究小穗顶部退化的分子机制及克服育种和生产实践中因穗顶部退化引起的产量损失具有重要的理论和现实意义。本研究报道了一个来源于中花11的穗顶部退化突变体,暂命名为Panicle Apical Abortion 2（paa2）。该突变体的穗顶部小穗发育异常、退化,后期退化部分脱落,稻穗形成秃尖,使穗粒数减少。遗传分析表明该突变体受1个显性基因控制。利用群体分离分析法（BSA,bulked segregation analysis）将PAA2基因定位在2号染色体的长臂端L2-33和L2-50之间,物理距离为80 kb的范围内。该研究结果为PAA2基因的图位克隆奠定了基础。

英文摘要：

The identification and cloning of novel gene controlling rice panicle apical abortion（ PAA） is meaningful to understand the molecular mechanism of the trait and reduce grain yield losses caused in rice production.We reported the result of fine mapping of a rice mutant,paa2,derived from tissue culture of Zhonghua 11. Phenotypic analysis found that the mutant panicle apical was abnormal growth and development,gradually degraded and shed during the later period,formed barren tip and resulted the grain number reduction. Genetic analysis revealed that the paa2 was caused by single dominance gene mutation. Using the BSA method,the PAA2 gene was finally mapped within the interval of 80 kb on chromosome 2,flanked between the newly developed markers L2-33 and L2-50. The results provided here would be beneficial for the map-based cloning of PAA2 gene.