Genetic Analysis And Fine Mapping Of A Lesion Mimic Mutant Spl31in Rice

A lesion mimic mutant temporarily designated as spl31was discovered in the progeny of an excellent indica restorer line Jinhui10with seeds treated by ethyl methane sulfonate (EMS). The mutant phenotype was normal before the three leaf period but with yellow bad spots on leaves after the four leaf period. Along with the growth and development of the plant, the number of spots didn’t show significant difference, whereas the lesion area gradually enlarged and developed with tawny margin. As the spl31matured, lesion spots interconnected between each other becoming a continuous piece, resulting in leaves’death. In this study. Jinhui10has been used as control to elaborate spl31mutant by histochemic analysis, genetic analysis, agronomic characters analysis, ultrasturcture observation and leaf photosynthetic characteristics and chlorophyll fluorescence kinetic parameters measurement. Furthermore, primary gene mapping and fine mapping have been performed to determine the location of spl31on chromosome. These results have been listed below, which have provided fundamental information to further functional and mechanism study of spotted leaf mutant in the future.(1) Trypane blue stain has been performed to explore the mechanism of leaf cell death. The results showed that the deep blue stained cells of lesion area presented discrete dietilution, while normal leaves of the wild type and the mutant has not been dyed, illustrating that the lesion mechanism of spl31may be spontaneously generated.(2)Both1000-grain weight, filled grains per panicle and seed setting rate of the mutant decreased as compared with the wild type, among which1000-grain weight has reduced1.1g, filled grains per panicle has reduced21.9%, seed setting rate has reduced9.86%.(3)The observation by transmission electronic microscope (TEM) demonstrated that most grana lamellae in spl31’s chroloplasts were irregularly stacked.(4)Photosynthetic characteristics of spl31were slightly higher than that of the wild type, while chlorophyll fluorescene kinetic parameters had no difference between the mutant and the wild type. These photosynthetic data showed that the mutation of spl31had no effect on PS Ⅱ.(5) Nipponbare was crossed with spl31to obtain mapping population. Genetic analysis suggested that spl31was controlled by a single nuclear recessive gene.621mutational F2recessive plants were used for gene mapping.And finally, Spl31locus was mapped on chromosome12near the centromere between ID104and ID11with physical distance of383kb and co-segregated with ID105.near the centromere between ID104and ID11with physical distance of383kb and co-segregated with ID105.