Characterization of a Novel Gain-of-Function Spotted-Leaf Mutant with Enhanced Disease Resistance in Rice

摘要

We here reported the identification and characterization of a novel gain-of-functionspotted-leaf 26(Spl26) mutant from an ethylmethylsulfone (EMS)-induced rice cultivar IR64.Spl26displayed 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.Spl26exhibited 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 inSpl26in 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 inSpl26with 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 305kb region between RM5490 and InDel42 on the short arm of chromosome 7. The data suggested thatSpl26is 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.