Diversity Evaluation Of 89 Strong Parents In Southwest Rice Region And Analysis Of Allelic Variation Of Two Regulating Granularity Traits

Rice is one of the three major crops.How to increase rice yield and improve rice quality is a constant issue in rice breeding.The southwestern rice region has unique climatic conditions of high temperature,high humidity,and low sunshine,and complex geographical and ecological conditions,and the germplasm resources are abundant.Sichuan,Chongqing,Yunnan,Guizhou and other provinces and cities have strong agricultural scientific research strength.Over the years,under the guidance of the theory of heavy panicle hybrid rice,a large number of high-efficiency,strong-potential,high-quality hybrid rice parents have been created,and thousands of them have been cultivated.New hybrid rice varieties have been approved at all levels throughout the country.In order to further improve the breeding level and efficiency of strong dominant hybrid rice in the southwestern rice region,it is necessary to systematically collect,identify and evaluate the existing germplasm resources and backbone parents in the southwestern rice region.In this paper,89 excellent restorer lines and conventional rice parental materials from Sichuan,Yunnan,Guizhou and Chongqing were collected,planted and traits examined.Genetic diversity analysis and phenotypic association analysis were carried out by SSR markers.At the same time,the following two results were analyzed for the key genes controlling granule traits,GS5 and GW2,and the following results were obtained:1.There is a significant correlation between the test materials in plant height,ear length,kernel number,1000-grain weight,and yield per plant.The yield traits were significantly positively correlated with tiller number,effective panicle,seed setting rate,grain number per panicle and grain width,and positively correlated with panicle length and grain length,and significantly negatively correlated with grain width.It indicates that the increase in yield can be achieved by appropriately increasing the number of tillers,the effective ear,the seed setting rate,the number of grains per panicle and the grain length.2.89 rice materials can be divided into two groups,namely japonica rice subgroup and japonica rice,with a similarity coefficient of 0.68.Among the 75 materials of the japonica rice subgroup,the population can be further divided into 15 groups with a similarity coefficient of 0.80,and the number of materials per group is 1-20.In addition to the special genetic backgrounds of Yihui 93,Chenghui 19,Q431,Shuhui 9801 and Shuhui 1388,the genetic relationship of the scorpion-type restorer lines selected in Sichuan,Chongqing and Guizhou is relatively close,but different.There are distributions in the clustering branches.The 14 materials of the japonica rice subgroup are clustered in distinct units.3.Using GLM model for correlation analysis,23 markers were associated with phenotype,and the interpretation rate of phenotype was 7%~17%.Four markers were correlated with phenotype by MLM model analysis,and the interpretation rate of phenotypic variation was For 15%,there are 3 markers associated with the number of grains per panicle,and the interpretation rate for phenotypic variation is 13% to 15%.4.The GLM model and the MLM model analysis jointly detected three markers,and the three markers adjacent to the region have phenotype-related genes.5.GS5 and GW2 alleles were abundant in haplotypes,and 42 mutation sites were detected in GS5 sequence,including 31 SNPs and 10 In Del loci,which constituted 16 haplotypes;128 GW2 sequences were detected.In the mutation site,74 variant sites were significantly correlated with the phenotype by MLM model analysis,and a total of 10 haplotypes were formed.6.GS5 and GW2 allelic variant haplotypes have been successfully applied to the breeding practice in the southwestern rice region.Among them,the most haplotype used in GS5 haplotype was GS5-13,which was 36 varieties,accounting for 40% of the whole population,followed by GS5-2,which was 19 varieties,accounting for 21% of the whole population;GW2 haplotype The most widely used is haplotype GW2-6,which is 40 varieties,accounting for 45% of the whole population,followed by GW2-7,GW2-8 and GW2-5,respectively,15,13,and 10 varieties,accounting for the entire 17%,15% and 11% of the group.7.Comparing the haplotypes of GS5 and GW2 in indica rice,it was found that GS5-15 and GW2-1 had the largest 1000-grain weight,so GS5-15 and GW2-1 could be used as dominant haplotypes in breeding practice,using molecular marker-assisted selection.Technology orientation selects these two haplotypes for application.The above results can be applied to breeding practice to a certain extent,and have a certain guiding role in the selection of parents in the breeding process.