Genetic Analysis And Fine Mapping Of Rice Dwarf Mutant Ds1

Rice is one of the important food crops in China. And plant height is animportant agronomic characters of rice which would directly influent ricelodging-resistance and rice production. The widely used of rice dwarf gene 'sd-1' hasleaded to the first 'green revolution'. Although many short-stem rice mutants wereidentified, only the 'sd-1' gene was widely used. In order to character the rice dwarfmutant sd1and to cloned this gene, this paper mainly do a systematic study onagronomic characters, physiology and genetic aspect of the rice mutant, meanwhilewe fine mapping the DS1gene, which provide the foundation for cloning andcharacterization this gene.The results could be summarized as follows:1. In this paper, the indica cultivar M804was mutagenized by60Co γ-Ray, and arice dwarf mutant (ds1) was obtained. The phenotype analysis showed dwarf plant,dark green leaves, compact plant type, strong growth vigor, and dwarf stem.Interestingly, the ds1has two less internodes compared to the wild type, and eachinternode length of the ds1became shorter, but not in proportion. In addition the plantheight is only48.1cm in mature period.2. The crossed experiment show that the F1generation show normal plant heightwhich indicate that the ds1is a recessive gene. Investigate the plant height ofds1/M804F2and M804/ds1F2the results show the separation ratio of normalcultivars and dwarf cultivars is3:1. The results indicate that the mutant ds1iscontrolled by a pair of recessive gene.3. The results also suggested that the DS1gene was located on chromosome5using326pair SSR markers, between the marker RM169and RM1237and the distantbetween to these two markers were8.3cM and6.2cM.4. According to the results of preliminary mapping, DS1gene was preciselylocated between the Indel-5-3and Indel-5-6, the distance was384kb.5. To reveal the allelic relationship between D1and the dwarf gene, we designed the primers according the D1sequence, then cloned the D1gene from ds1and M804,With sequencing, the result showed that the mutant mutate at two sites compared tothe wild type, one is at the154bp from A to G which may lead to losing of GTPbinding site. the other happen at927bp from A to G, this site is in a intron which maynot influent the gene expression. Therefore it maybe the mutation site in the154bpwhich leading to the losing of GTP binding site and the dwarf trait.