Fine Mapping Of( Semi-dominant Dwarf1) Si-dd1 Gene In Rice(Oryza Sativa L.)

Plant height is one of the most important agronomic traits in plants, which contributes to plant yield. Too high or too dwarf will affect the quality of rice grains. In recent years, with the development of sequencing, structural genomics, functional genomics and bioinformatics, scientists have cloned a lot of rice dwarf genes and have achieved many important results. People are always looking for appropriate plant height which adapt to various water and fertilizer conditions for development of high-yield varieties. In this study, a mutation generated by tissue culture of Nipponbare and the mutant has a performance of Semi-Dominant dwarf. We performed anatomical analysis of the mutant and the genetic analysis; By map-based cloning Si-DD1 is located into a region of 244 kb on the short arm of chromosome 6, these results laid a theoretical foundation of semi-dominant dwarf molecular mechanisms. The results of this paper were as follow:1. Identification and phenotypes of Semi-Dominant Dwarf mutant Si-dd1 : The mutation generated by tissue culture of Nipponbare, Completely dominant dwarf mutant Si-dd1 is identified in the seedling stage until 3-leaf stage. Compare with the wild type, Si-dd1(AA) has a delayed growth period and a serious decline in the rate of seed and serious dwarf in plant. The height of dominant dwarf Si-dd1(AA) is about half of the wild-type, while Si-dd1(Aa) is 20 cm less than the wild-type.(measured at Hainan).2. Genetic analysis of Si-dd1 : F1 plants from Si-dd1 and 9311 are presented semi-dwarf. The ratio of Si-dd1(AA)、Si-dd1(Aa) and WT in F2 generation presents 1:2:1. F2 generation cross from Si-dd1(Aa)and 9311 is presented semi-dwarf and wild. Genetic analysis shows that mutant Si-dd1 was controlled by a semi-dominant nuclear gene.3. Hormone response of Si-dd1:GA and BR responses indicate that both the mutant Si-dd1(AA) and wild-type are successively increased by treat exogenous hormone GA, while does not react to BR.4. GID2 protein expression analysis: The results showed that, GID2 expression between Si-dd1 and WT is not related to GA.5. Cytological analysis :Cytological observation analysis showed that the leaf midrib has a smaller stoma, but mesophyll cells and stem vascular bundles increased. Cells become density and uneven. Dominant Dwarf cells significantly become more density and smaller.6. Fine mapping of Si-DD1:Map-based cloning method was used to map the gene on the short arm of chromosome 6 between markers M2 and M3, Another six makers were developed for fine mapping,and Si-DD1 is located to a region of 244 kb between the markers P3 and P4. It was different from the gene which have been found already.