QTL Mapping Of Spike Main Traits In Wheat-rye Derivatives

Wheat is the most widely planted crop and also belongs to the top three cereal crops in China.Due to the continuous increase in population and quality of life,the demand for wheat in China has increased dramatically,making it extremely urgent to improve wheat yields.Increasing spike length,total number of spikelets per spike and spikelet bearing density is an important way to increase wheat yield.In order to resolve the genetic characteristics of wheat spike length(SL),total spikelets per spike(TSS)and spikelet bearing density(SC)and to find QTL for superior spike traits,rye has the characteristics of more total spikelets per spike and longer spikelets,which can be transferred to common wheat to produce wheat germplasm with large spikes and more spikelets.In this study,a RIL population was constructed to screen for superior wheat spikelet trait loci using Lan Xiaohe with large spikelet traits.The genetic analysis was carried out using a genetic model with a master gene and multiple genes,and the QTL loci were localised using a mixed grouping analysis(BSA method)combined with exon capture liquid phase microarrays and molecular markers.The main findings of this study are as follows:1.Statistical analysis of the phenotypic identification data of the three traits at 4 points in2 years showed that the variation of all traits in the RIL population was extensive and the environmental effects were highly significant.The heritabilities of spike length,total number of spikelets per spike and spikelets compactness were 64.87%,64.11% and 65.83%.2.The best genetic models for the three traits were MX2-AI-A,MX2-AI-AI and 4MGAI.The heritabilities of the main genes were 66.91%,54.54% and 97.06%,respectively,and the heritabilities of the two traits with polygenic control were 25.73% and 11.73%,respectively.The two traits with multiple genes were 25.73% and 11.99%,respectively.All three wheat spike traits were quantitatively inherited and predominantly polygenic.3.The SNP-index and ED association analysis of the exon capture sequencing results for the three traits yielded the following association regions.The results of the intersection of the two association methods were,SL,1B: 41.66-117.60 Mb and 594.96-650.55 Mb,2B: 623.31-680.52 Mb,3A: 20.17-21.19 Mb,and 6B: 725.64-726.39 Mb.TSS,2B: 52.32-140.47 Mb,3B:681.88-756.81 Mb,3A: 714.66-727.46 Mb,4A: 738.52-745.30 Mb.SC,2B: 620.74-689.47 Mb,4B: 561.85-573.14 Mb,7A:575.49-671.93 Mb.4.Further QTL localization was performed on the association regions of the three traits using interlocking SSR molecular markers and phenotypic values of the spike traits,and a total of 10 associated QTL were located,with individual QTL contribution rates ranging from 6.8-33.9%.Three QTLs related to spike length were located on chromosomes 1B and 2B,four QTLs related to total spikelets per spike were located on chromosomes 2B and 3B,and three QTLs related to spikelets compactness were located on chromosomes 2B and 7A.The three QTL,QSL.nwafu-1B.1,QSL.nwafu-2B.2 and QSL.nwafu-7A.1,could be detected in multiple environments.