Genetic Analysis And Gene Mapping Of A Semi-dwarf Mutant In Rice (Oryza Sativa L.)

Plant height is one of the most important agronomic traits of rice. Over high plant would easily result in plant lodging and output reducing. Researching to the dwarfism makes for increasing the variety of using of dwarf fountain, avoiding oneness of the dwarfism breed genetics, and also creating condition for the break through of rice breeding production. Thus it is very important to unearth new dwarfism, investigate their dwarf genes, and finally make use of these genes.In this study, we described the identification, characterization and fine mapping of a new rice semi-dwarf gene, which was segregated from sd-k, a natural dwarf mutant origined from kasalath. The main results were as follows:1,The mutant behaved normal phenotype in the seeding stage, but height of the mutant started to appear dwarfing after jointing stage. The height of sd-k was about 100cm, 50cm lower than the wild type's height at maturity. The reducation of plant height is expressed through the shortening on the length of all internode. Comparing with the wild type, the mutant had more slender stem and leaves, smaller panicle and seeds, degradation of the arista, higher grain density and 6-8 days advanced in heading date. There was no difference in tillering and seed setting rate.2,The mutant was treated with GA3 and BL in the seeding stage respectively. Based on the results, we can speculate out that there were no defects in the pathway of GA and BR synthese and signal transduction.3,After crossed with different height materials, the genetic analysis indicated that the dwarf character of sd-k was controlled by a pair of recessive gene.4,According to the result of genetic amylase, the F2 population of sd-k/KN and sd-k/Kuidao was used for the map population. By utilizing the method of SSR and InDel markers binding with populations analyzing, sd-k was narrowed down to a candidate genomic region of 115 kb long defined by InDel markers YL-9 and YL-6 near the centromere of chromosome 2. Gene prediction analysis indicated that there were 20 open reading frames in this region, of which 6 encoding function proteins,14 encoding hypothetical proteins or unknown proteins. The study has laid a good foundation for further fine mapping, cloning and the molecular mechanism of sd-k study.