Genetic Composition Analysis And Yield-Related Traits Improvement Of Backbone Parent Shuhui527

The rice backbone parents have an important influence on renewing varieties,and defining the genetic of the yield-related traits in the backbone parents will help breeder cultivate new backbone parent,which is very significant for rice breeding work.Shuhui527(527R)is an optimal restorer line with giant panicles,high heterosis,high combination ability,which was bred by Rice Research Institutes of Sichuan Agriculture University in 2000.As a backbone parent,527R has reached an organic integration of high yield,good quality,multi-resistance and wide adaptability in traits,bred a large number of new varieties and spawned a series of excellent restorer lines in breeding application.In this study,we performed genome wide screening analysis on 527R,6 parents and 18 progenies developed from 527R by a high-density SNP chip to make the genetic structure and genetic basis of 527R clear.Based on SNP data,we explored the genome constitutions of 527R,the source and inheritance of its key genome segments.Then combining with the information of those cloned yield-related genes,some important candidate genes for explaining 527R’s good traits were found out.Meanwhile,we discovered many sites maybe were associated with important traits of backbone parents using Genome-Wide Association Study(GWAS).At last,we attempted to find the possibility of using CRISPR/Cas9 to make further improvement on the yield-related characters of 527R.The results were as follows:1.The major origin and the key region of 527R genome were confirmed through high-density SNP chip combining with the investigation of agronomical traits.1)The investigation of agronomical traits showed that the plant height of 527R was more close to G630 and some grain traits of 527R such as TGW have more possibility to be originated from the pedigree of G630-R1318-527R;whereas the effective panicle number is inclined to originated from the pedigree of IR24-527R,so the excellent agronomic characters of 527R may mainly coordinated the G630 large grain character and the tillering ability of IR24.2)A total of 149 fragments(52,875,065bp)of 527R’s whole genomes derived from G630,accounting for 14.202%of the whole genomes.Moreover,others parents’ contribution rate were between 3.58-0.07%.In terms of the contribution rate,IR24>F36-2>GU154>IR15449.And there are 366 specific fragments(5,348,693 bp)derived from G630,accounting for 1.4%.Others parents’ contribution rate were between 0.27-0.02%,and sorted by the extent of parents’ contributions,F36-2>GU154>IR24>IR1544.3)Analysis on the inheritance segments form 527R to its’ progenies,a total of 3,147 fragments(65,305,677-bp)were found out which can be stably pass from 527R to all its derivative restorer lines,accounting for 17.54%.Because of the good behavior of all derivative restorer lines,all of these fragments will be the key region of 527R genome.2.By comparing the known genes with the key genomic regions,the possible molecular basis of 527R excellent yield characters and 527R key regions were discussed.1)13 genes were located in the regions derived from G630,including GW8,GS5,GW2,EP3,OsFAD8,etc for grain weight,plant architecture and yield,Stress and yield.Conversely,the 4 genes located in the regions derived from IR24 were mainly associated with tiller and panicle type.The discovery of these genes suggested a possible molecular basis for the formation of excellent traits of 527R.2)25 yield-related genes were located in the key regions which stable inheritance in the derived varieties(restorer lines)from 527R,covering key yield gene of restorer line Ghd7,genes for grain number,grain shape and grain weight,such as Gnla and some stress-related genes,and these genes may together constitute the molecular basis of big grain and heavy spike,good plant-type and other traits that derivative line inherited from 527R.3.261 associated loci were detected by genome-wide association analysis on many years’agronomic traits investigation date and SNP data,and most of them were associated with tiler number,among which 132 loci were located in the specific regions,including the origin and key region of 527R.There are 9 cloned yield-related genes in rice were discovered by searching at all sites.3.261 associated loci were detected by genome-wide association analysis on many years’agronomic traits investigation and SNP data,and most of them were associated with tiler number,among which 132 loci were located in the specific regions,including the origin and key region of 527R.There are 9 cloned yield-related genes in rice were discovered by searching at all sites.4.CRISPR/Cas9 technology was used to knockout some yield-related genes,making they function lost.And the loss-of-functin mutants of 527R were obtained.527R variant strains with improved traits were obtained preliminarily by gene knockout.Gnla knockout can achieve 7 variation types,among which four types were homogenous plants,and the grain number per spike of partial variant strains were increased significantly than 527R’s;GW2 knockout can achieve 5 variation types,all of which were homozygote,and the TGW of every type were more than 40g;DEP1 knockout can achieve 6 variation types,among which three types were homogenous plants,and partial variant strains have shown great performance with semi-erect compact panicle and remarkable increases in grain number per panicle.At all,those targeted mutagenesis transgenic lines shown above have great significance in modifying the yield-related traits of 527R.