Phenotypic Analysis, Gene Identification And Application Of Two Grain Width Materials In Oryza Sativa Subsp.Indica

Rice one of the three major food crops in the world increasing rice production and improving quality of rice is of great significance and the important goals for rice breeding.The grain shape, as the most important determinants of thousand seed weight, is mainly evaluated by grain length, grain width, grain thickness three factors. Grain shape,a complex quantitative trait,is not only an important production trait,but also a significant indicator of rice appearance quality which affects the length/width ratio,chalky,and cooking and eating quality as well.Therefore, the study of rice grain shape and quality can deepen the understanding of the molecular genetic basis of rice yield and quality,which provids theoretical guidance for high yield and quality breeding practices,and offers molecular biological mechanism basis to elucidate crop yield and quality formation.In this study,two indica rice EMS mutants 2199 and single segment substitution lines(SSSLs) SSSLs5-l,with different sources and grain width,were analyzed. Phenotype analysis,gene identification and breeding potential assessment.The main results are as follows:l.We investigated the phenotypic,agronomic and quality of 2199,SSSLs5-l,as well as their parent Shuhui527 (R527) and 9311.These results showed thatxompared with the wild type R527,the average variation of mutant 2199 is increase in grain width and grain weight, decrease in grain length and length/width ratio.Compared with the 9311,the average change of SSSLs5-1 is increase in grain width and grain weight,decrease in grain length and length/width ratio.The difference of the two materials and their corresponding parental wild was mainly focused on the chalky rate and chalkiness degree. Both of the two materials chalky rate and chalkiness degree are higher than those of the corresponding wild type.2.Through the genetic analysis of the 2199/R527 F2 populations,we found that the grain width showed a bimodal distribution,and the ratio of narrow grain to the wide grain is 3:1,indicating that in these populations,the grain width by a single recessive gene controls the main effect.3.The sequencing analysis of known grain width gene indicated that, similarly with the deletion fragments of grain width gene gw5 in japonica,SSSLs5-1 and 2199 is lack of 1212bp bases when compared with their parents R527 and 9311.Also,the linkage analysis showed that all the extreme wide grain mutants were lost, uncovering that gw5 is the target gene.4.The electron microscope observation on the inside epidermis of the outer glume showed that both cell numbers of 2199 and SSSLs5-1 have significant increased,while the cell width is no difference, indicating increasing of cell numbers is the main cause of the increase in grain width.5.We also measured the filling rate of 2199, R527, SSSLs5-1 and 9311.We found that during 3 days to 18 days after filling period, filling rate is faster that the initial period.The filling rate of 2199 and SSSLs5-1 is significantly higher than their parents respectively.Laterly,the filling rate gradually decrease until grains completely full,implying that during the equal time,2199 and SSSLs5-1 can transport more assimilates to the grains, and finally formed a higher grain dry matter accumulation.6.To evaluate the applicated capacity of GW5 in three-line breeding,we crossed 9311 and R527 with four classical sterile line and measured these yields and quality of its F1 offsprings.The results indicated that the thousand seed weight of the F1 of 2199 and Gang 46A group is the highest increase,but little increase in yield. Morever,its chalkiness rate is high and its appearance quality is poor.The three materials crossed with SSSLs5-1 vary much.Compared to the corresponding parental controls,the milled rice rate of abcgl5/SSSLs5-1 raised,while the chalky rate, chalkiness degree and yield of individual plant reduced.The milled rice rate,chalky rate,chalkiness degree and yield of individual plant of Luo red 4A/SSSLs5-1 and Y58s/SSSLs5-1 increased. Integrated both rice yield and quality factors,SSSLs5-1 values more than 2199 in breeding,indicating potential gw5 gene in rice breeding based on different genetic backgrounds vary.