QTL Mapping For Yield Traits Based On Genetic Map Of Unigenes In Wheat

Wheat?Triticum aestivum L.?is one of the important staple crop in China.The improvement of high-yield wheat varieties is one of the most basic ways to improve wheat yield per unit area and ensure national food security and sustainable production.Based on the previously established unigene genetic map of RIL population derived from the cross of "shannong 0431×lumai 21"?SL-RIL?,QTL analysis was performed for 10 yield related traits.The result should be helpful for molecular marker assisted breeding in wheat yiled breeding programs and isolation of related gene.The main results are as follows:?1?According to the unigene annotation from the lastly genome of CS v1.0,we newly constructed the genetic map of SL-RIL,which was based on the unigene order of v1.0.The final map included 20988 unigenes on all the 21 chromosomes with the total length of 54717.5 cM,the average density of 2.61cM/unigene and 280 gaps.?2?The coefficients of variation for 10 yield traits showed a large range of variation under seven environments including the mean value?AV?.The largest coefficient of variation was the top number of sterile spiklet per spike?TSSS?under TA13 environment?209.99%?.The smallest coefficient of variation was the number of spikelets per spike?TSS?under AV?4.82%?.The most heritability was 93.77% for spike length?SL?,and the least heritability was 54.05% for theoretical grain yield?TGY?.According to the analysis of variance?ANOVA?,the variances of the 10 yield traits were all significant at P?0.001 level both for genotypes and environments.The correlation between traits was mostly significant.?3?QTL analysis for the 10 yield traits under seven environments showed that a total of 617 additive QTLs were detected?761 single QTLs for trait-environment combinations?distributed on all the 21 wheat chromosomes.A number of 297 QTLs showed positive additive effects,indicating that the increase effects were originated from the female parent shannong 0431;however,320 QTLs showed negative additive effects,indicating that the increase effects were originated from the male parent lumai 21.The contribution rate for a single QTL ranged from 0.82% to 32.35%.Among them,239 additive QTLs were related to grain yield and its constituent factors on 21 chromosomes explained from 1.44% to 18.81% of phenotypic variations.There were 378 additive QTLs related to plant height and panicle traits on 21 chromosomes explained from 0.82% to 32.35% of phenotypic variations.?4?A total of 27 RHF-QTLs were detected on 14 chromosomes?1A,1B,2A,2B,2D,3B,3D,4B,4D,5A,5B,6A,6B and 6D?for base sterile spikelet number per spike?BSSS?,fertile spikelet number per spike?FSS?,grain number per spike?GNS?,plant height?PH?,spike length?SL?,1000-grain weight?TGW?and total number of spikelets per spike?TSS?.The contribution rate ranged from 5.63% to 24.21%.The additive effect of 14 RHF-QTLs was positive,indicating that the increase effects were derived from maternal shannong 0431;and 13 RHF-QTLs was negative,indicating that the increase effects were derived from parental lumai 21.Six RHF-QTLs were related to yield and yield components,and 22 RHF-QTLs were related to plant height and panicle traits.A number of 16 RHF-QTLs were detected with over 10% contributions,which were major RHF-QTLs.?5?Four QTL clusters?C1-C4?were obtained,which were located in the ranges of S₀041919-S₀041982,S₀332677-S₀332934,S₀623787-S₀624056 and S₀903283-S₀903554 on chromosome 1A,2D,4D and 6B,respectively.