We here reported the identification and characterization of a novel gain-of-function spotted-leaf 26 (Spl26) mutant from an ethylmethylsulfone (EMS)-induced rice cultivar IR64. Spl26 displayed reddish- brown lesions that firstly appeared on the leaf tips at the early tillering stage and spread gradually downward to cover the whole leaf blades that wilted subsequently. The lesion development was light- dependent under natural conditions. Spl26 exhibited impaired photosynthetic capacity with decreased chlorophyll content and lowered photosynthetic parameters which ultimately led to the poor performance of agronomic traits. Severe cell death occurred in Spl26 in accompany with increased malonaldehyde level and membrane ion leakage rate, elevated reactive oxygen species (ROS) accumulation, altered ROS scavenging activities, increased DNA fragmentation and decreased soluble protein levels. Defense responses were activated in Spl26 with enhanced resistance to rice bacterial blight, up-regulation of defense response genes and altered endogenous hormone levels. The spotted-leaf phenotype is controlled by a single dominant nuclear gene localized to a 305 kb region between RM5490 and InDel42 on the short arm of chromosome 7. The data suggested that Spl26 is a novel gain-of-function spotted-leaf mutant with enhanced bacterial disease resistance and immunity-associated premature leaf senescence and would provide the basis for cloning of the target gene.

我们在这里报告了从乙基甲基砜（EMS）诱导的水稻品种IR64获得的新型功能性斑点叶26（Spl26）突变体的鉴定和表征。Spl26显示出红褐色的病斑，该病斑在分till初期首先出现在叶尖上，并逐渐向下扩散以覆盖随后逐渐萎缩的整个叶片。在自然条件下，病变的发展是光依赖的。Spl26的光合能力受损，叶绿素含量降低，光合参数降低，最终导致农艺性状表现不佳。Spl26中发生严重细胞死亡伴随着丙二醛水平和膜离子泄漏速率的增加，活性氧（ROS）积累的增加，ROS清除活性的改变，DNA片段化的增加和可溶性蛋白水平的降低。Spl26中的防御反应被激活，增强了对水稻白叶枯病的抵抗力，防御反应基因的上调和内源激素水平的改变。点叶表型受单个显性核基因控制，该基因位于7号染色体短臂上RM5490和InDel42之间的305 kb区域。数据表明，Spl26 是一种新型的功能获得性点叶突变体，具有增强的细菌抗病性和免疫相关的过早叶片衰老，将为克隆目标基因提供基础。