Genetic Analysis And Molecular Mapping Of Male Sterile Mutant D60 And Yellow-Green Mutant 5043ys In Rice

In the natural environment, the male sterility mutation of flowering plant and the leaf color mutation of higher plant are common phenomenons. The male sterility of plants refers to a phenomenon that the male organs degradation or maldevelopment cause it can’t produce the functional pollen or male gamete, while the female organs develop normally and can accept normal pollen and fertilization. In addition, the leaf color mutation is also called chlorophyll deficient mutant, beacuse these mutant genes that caused the leaf color variation is often directly or indirectly affect biosynthesis or degradation of its chlorophyll, then changed the content of chlorophyll. In recent years, people had made a great progress on rice male sterility and leaf color mutation in the molecular mechanism, at the same time, the potential values of the two types of mutations in the actual production also attract the attention of the people.The male sterile mutant D60 in this study was isolated from indica variety G46B through EMS chemical mutagenesis. Its anther was thinner, wizened and indehiscent, the outward appeared milkwhite. The mutant belonged to non-pollen type of male sterility because there was no pollen in its pollen sac. At the same time, compared with its wild-type, the mutant’s plant height decreased by 13.9%, number of spikelets per panicle decreased by 13.5%, panicle exertion decreased by 245.2%, and its seed setting rate was 0, in which there were significant difference between the mutant and its wild-type. Genetic analysis showed that the male sterile trait of D60 was controlled by a pair of recessive nuclear genes. Genetie mapping of the mutant gene was conducted using molecular marker technique and F2 mapping populations of D60/ZH11. The result suggested that the sterile gene was located between SSR marker RM247 and InDel marker C9 on rice chromosome 12, with genetic distance of 18.6 cM and 13.0 cM, respectively. In order to get further position of the target genes, another eight InDel markers with parental polymorphisms were developed. Finally, the mutated gene was mapped between the two InDel markers C4 and C5, with genetic distance of 0.7 cM and 0.2 cM, respectively. The InDel markers C4 and C6 limited the mutant gene in a region of about 1.7 Mb. This region contains the male sterile gene mil2 that has been cloned, and the mil2 gene is close to InDel marker C5. The male sterile characteristics of mil2 is similar with those of D60 mutant, so we consider that the mutation gene in D60 maybe be allelic to the mil2 genes. But the allelism of D60 and mil2 need to be further investigated.The leaf color mutant 5043ys was obtained from japonica variety Nipponbare through EMS chemical mutagenesis. Its leaf colour was bright yellow at seedling stage, and gradually turn yellow-green colour at the later stage. Investigation suggested that there was significant difference between the 5043ys mutant and the wild-type in plant height and seed setting rate, in which the mutant decreased by 15.1% and 9.6%, respectiovely. The content of photosynthetic pigments of the 5043ys mutant was significantly differenent from its wild-type. At seedling stage, the contents of chlorophyll a and chlorophyll b in the mutant were only 35.48% and 30.79% of its wild type, respectively. At heading stage, those in the mutant were 61.14%and 48.94% of those in the wild-type, respectively. Observation through the electron microscope showed that most of the chloroplast in 5043ys mutant were irregular shape, and there were a lot of vesicles structures inside, the number of grana lamellae was reduced. Genetic analysis showed that the 5043ys mutant traits were controlled by a pair of recessive nuclear genes. Genetie mapping of the mutant genes were conducted by using moleeular markers and F2 mapping populations of 5043ys/MH63. The last results suggested that the mutation gene harbored in 5043ys was located between the SSR maker RM502 and InDel maker YS3 on the long arm of rice chromosome 8, with genetic distance of 0.6 cM and 0.2 cM, respectively. The physical distance between the two markers was 102.5 kb, in which there were 14 putative genes. Compared with the leaf colour mutant genes reported, the mutant gene in 5043ys was considered to be a novel mutant gene for leaf colour in rice, and designated tentatively as 5043ys(t).