Genetic Analysis And Gene Mapping Of The Dwarf Mutant Of Rice

Tiller number and plant height, which closely related to efficiency of photosynthesis and lodging resistant,and are important traits of plant type and influence grain production in rice. In the 1960s,dwarfism gene was adopted to improve crop quality and significantly to increase the grain yield. It is important to reveal the molecular mechanism of plant height, which has an important significance on rice seed breeding. In this study, we reported a dwarf mutant from an M2 population of advanced backcross populations through EMS mutagenesis, and named as dw, Observed from agronomic traits survey, phenotypic, genetic analysis and gene location and so on were studied.The main research results are as follows:1.The drawf mutant dw was derived from the EMS induced mutation.Compared with wild type,the dw mutant plant height was decreased obviously. The dw mutant showed dark green leaves, normal tiller numbers, stem stout, normal seed-setting rate.2.Genetic analysis indicated that the mutant was controlled by a single recessive gene.In this study, two F2 populations were developed from the crossing between dw and Nipponbare, dw and 93-11, respectively. Investigation the normal plant and mutation plant, the segregation rate was 3:1 that corresponded to Mendal’s law of separation. The results illustrated that the mutant was controlled by a single recessive gene.3. The gene was located on the long arm of chr5, In the study,451 F2 individuals derived from d63 and Nipponbare cross were screened for the fine mapping, and dw was located on the long arm of chr5 between RM18410 and RM18419. The physical region was 143.2kb.4.Gene prediction was made according to the mapping results and the " Rice Genome Annotation Project Rice Genome Browser-Release 7" information released online (http://rice.plantbiology.msu.edu/). The results showed that there were 14 candidate genes in the limited genomic region. According to the reported literature for comparison, found this region had a dwarf gene dl in rice was located on LOC_Os05g26890, and cloned.5.The sequences comparison from dw and the wild type showed that dw in the 8th exon of LOC_Os05g26890 gene happened on a single-base mutation (726bp:Gâ†'C). This mutation position is located in a exon, which may lead to losing of GTP binding site and the drawf trait.