Genetic Identification And Gene Mapping Of A Short Grain And Lax Panicle Mutant Sgll In Rice

Rice is one of the most important food crops, nearly half of the world population feed on rice. So improve the yield of rice is very important for food security. The yield of rice is decided by productive panicles, grain number of panicle and 1000 grain weight. So the grain weight and panicle shape has a great influence on rice production.In this research, we used EMS (Ethyl Methanesulfonate) to chemical mutagenesis the japonica cultivar Nipponbare, and got a short grain and lax panicle mutant, named sgl1. Agronomic traits both in wild type Nipponbare and sgl1 were observed, and the results suggested that the length of sgl1 grain became shorter, the grain density of panicle in sgll was sparse,1000 grain weight of sgll mutant was decreased, and the height of sgl1 mutant was also reduced compare with Nipponbare. The sgl1/G46B F2 population was used as a positioning population for fine mapping of the candidate gene. The main results are below:1. The statistics of main agronomic traits in sgl1 mutants:grain length of sgl1 became shorter while the width was almost not changed, the length of grain was reduced from 0.69 cm in the wild type to 0.53 cm in sgl1 mutant, and the width of grain in both wild type and sgl1 mutant was 0.33 cm, caused the grain length and width ratio reduced to only 1.6 in sgl1, but the wild type was 2.1.1000 grain weight of sgl1 mutant reduced 19.4% from 26.3 g in wild type to 21.2 g in sgl1. The number of grain per panicle decreased from 126 in wild type to 101 in sgl1 (main spike), reduced 16.7%. Because the shorter grain and fewer number of panicle grain in sgl1, made the grain density of sgl1 became sparse. The sgl1 mutant height was reduced, the main reason is due to the shortened down of first section, the second section and panicle length reduced a little.2. Genetic analysis of sgl1:Crossed the mutant sgl1 and wild type parents Nipponbare. Then we planted Nipponbare, F1 and F2 in Chengdu, investigated sgl1 and Nipponbare agronomic traits in entire growth period; we found that the F1 plants was normal phenotype, F2 plants was divided into normal plants or short grain and lax panicle plants. The segregation ratio was in accordance with 3:1. So the short grain and lax panicle trait is controlled by one pair of recessive nuclear genes.3. Gene mapping of the mutant gene SGL1:Used sgll/G46B F2 generation as the mapping population. The gene was located on fourth chromosome between the two markers RM6997 and RM252. The genetic distances for the 2 markers were 15.5 cM and 10.1 cM. In order to fine mapping the target sites, according to the published genome sequence data of japonica rice Nipponbare and indica rice 9311, we used Primer Premier 5 software to design the insertion/deletion (InDel) markers. Finally we got 5 parental polymorphic InDel markers. The fine-mapping genomic region is 190 kb-length between C3 and C4 makers.