Map-based Cloning Of A Spotted-leaf Lesion Mimic Spl33(t)Gene In Rice

Lesion mimic is spontaneous lesions on plant leaves,stems,or other tissues in the absence of pathogen infection,stress,or wounding.The phenotype of lesion mimic is similar to disease lesions caused by phytopathogens.Study on lesion mimic mutants has theoretical significance to elucidating plant programmed cell death,plant defense mechanisms.In the present study,we identified a novel rice spotted leaf mutant,named as spl33(t)(transiently).By dveloping F2 segregation population,phenotypic investigating,sampling,and analyzing with molecular markers,the spl33(t)was mapped in a 49 kb region on chromosome 7.Further sequencing analysis of the predicted genes in the mapped 49 kb region successfully identified a mutanted candidate gene.Sequence prediction showed that this candidate gene encodes a glucose/ribitol dehydrogenase family protein,which has not been found to control plant lesion mimic formation before.To confirm the map-based cloning result,we further designed a complementary experiment.Using wild type rice genome DNA,we cloned the complete wild type gene spl33(t),and a complementary construct was developed.In addition,cDNA of the spl33(t)gene was cloned and an overexpression construct for spl33(t)was developed.The results of this study provide a solid foundation for illuminating molecular mechanism of cell death and disease defense response regulated by spl33(t).