| As one of the four major oil crops,rapeseed is widely planted in China and all over the world.The rapeseed acreage of China was 7.43 million hectares and the total output was 14.01 million tons,which accounted for 20.56%and 22.23%of the world respectively.With the rapid growth in global demand for rapeseed oil,increasing the oil content in seed and improving the quality of oil were the main objectives of rapeseed breeding.Analysing the genetic basis and mapping the QTL of main agronomic and quality traits,such as pod length and oil content,were greatly helpful for the high yield and high quality rapeseed breeding.In this study,two rapeseed lines APL01,Holly and their RIL populations were used to analyse the genetic basis using major gene and polygene mixed models.A high-density genetic linkage map of rapeseed(Brassica napus L)was constructed based on SNP markers,which included 19 linkage group,57 SSR markers and 2812 bin.This map covered 2027.53cM and the average distance between markers was 0.72cM.The main results were as follows:1.Genetic analysis of the main agronomic and quality traits in rapeseedThe major gene and polygene mixed genetic model was used to analyze the P1,P2 and RIL population of rapeseed cross between APL01 and Holly.The results were as follows:(1)Genetic analysis of the important agronomic traitsThe genetic model of siliqua length was fitted for 4MG-AI,which was four epistasis-additive major genes model,the additive and epistasis of major genes were 0.13 and-3.62,respectively,and the heritability value of the major genes reached to 88.89%.The genetic model of plant height was fitted for PG-AI,which was multi-gene epistasis effect model.The genetic model of branch point height was fitted for MX1-A-AI,which was one additive effect major gene and epistasis additive polygene model,and the additive effect of major gene was 20.33.The genetic model of number of primary branches was fitted for PG-AI,which was polygene epistasis model.The genetic model of number of secondary branches was fitted for 3MG-AI,which was three epistasis-additive major genes model,the additive and epistasis effect of major gene were 1.58 and 2.91 respectively,and the heritability value of the major genes reached to 32.58%.The genetic model of the length was fitted for 4MG-EEEA,which was four equal additive major genes model,the additive effect of major genes was 2.22.(2)Genetic analysis of the main yield trairtsThe genetic model of yield per plant was fitted for 3MG-CEA,which was three completely equal major genes model,the additive effect of major genes was 12.57,and the heritability value of major genes was 57.08%.The genetic model of silique number of main axis was fitted for MX3-AI-AI,which was three epistasis-additive major genes and epistasis-additive polygene model,the additive and epstasis effect of major genes were 21.34 and 28.46 respectively,the heritability value of the major genes reached to 25.39%.The genetic model of seeds per silique was fitted for PG-AI,named polygene epistasis model,the epistasis effect of polygene was 4.22.The genetic model of silique number of the primary branches was fitted for PG-AI,named epistasis additive polygene model.The genetic model of silique number of the secondary branches was fitted for MX3-AI-A,which was three epistasis-additive major genes and additive polygene model,the additive and epistasis of major genes were 18.50 and 24.90 respectively,the additive effect of polygene was-8.59,the heritability value of the major genes reached to 24.83%.The genetic model of thousand-seed weight was fitted for 4MG-AI,which was four epistasis-additive major genes model,the additive and epistasis of major genes were 0.1815 and-0.4185 respectively,the heritability value of the major genes reached to 98.8%.(3)Genetic analysis of the oil contentThe genetic model of oil content was fitted for 4MG-AI,which was four epistasis-additive major genes model,the additive and epistasis effect of major genes were 23.79 and-17.30 respectively,the heritability value of the major genes reached to 96.91%.2.QTL mapping of main agronomic and quality traits in rapeseedThe QTL of main agronomic and quality traits in rapeseed were detected by using WinQTLCartographer 2.5 software through composite interval mapping.The results were as follows:(1)QTL mapping of main agronomic traits in rapeseedThree QTLs associated with plant height in rapeseed were detected,which located on linkage groups A3,A6 and A9,and explained the phenotypic variation ranged from 5.57%to 8.36%.Ten QTLs associated with the branch point height in rapeseed were detected,which located on linkage groups A7,A9,C6 and C9,and explained the phenotypic variation ranged from 5.15%to 14.48%.Eight QTLs associated with the main axis length in rapeseed were detected,which located on linkage groups A4,A7,C3 and C6,and explained the phenotypic variation ranged from 4.75%to 19.88%.One QTL associated with the primiary branch number in rapeseed was detected,which located on linkage group A4,and explained the phenotypic variation 7.86%.Two QTLs associated with secondary branch number in rapeseed were detected,which located on linkage groups A6 and A9,and explained the phenotypic variation ranged from 7.32%to 7.77%.(2)QTL for yield-related traits in rapeseedThree QTLs associated with silique number of primary branch in rapeseed were detected,which located on linkage groups A1 and A6,and explained the phenotypic variation ranged from 4.78%to 10.73%.Five QTLs associated with silique number of secondary branches in rapeseed were detected,which located on linkage groups A5,A6,A9 and C4,and explained the phenotypic variation ranged from 4.96%to 9.93%.Two QTLs associated with silique number of main axis were detected,which located on linkage groups A2 and C2,and explained the phenotypic variation ranged from 4.77%to 7.70%.Senyen QTLs associated with seed number per silique in rapeseed was detected,which located on linkage group Al,A3 and C6,and explained the phenotypic variation 0.11%to 10.75%.One QTL associated with yield per plant in rapeseed were detected,which located on linkage group A3,and explained the phenotypic variation 5.0%.Six QTLs associated with thousand-seed weight in rapeseed were detected,which located on linkage groups A3,A6,A7,C2 and C6,and explained the phenotypic variation ranged from 4.77%to 15.05%.(3)QTL for fatty acid composition and oil content in rapeseedSenven QTLs associated with C16:0 in rapeseed were detected,which located on linkage groups A5,A9,C3 and C7,and explained the phenotypic variation ranged from 4.55%to 16.20%.Six QTLs associated with C18:0 in rapeseed were detected,which located on linkage groups A4,A7,A8,C1 and C3,and explained the phenotypic variation ranged from 4.66%to 13.71%.Four QTLs associated with C18:1 in rapeseed were detected,which located on linkage groups A5 and A9,and explained the phenotypic variation ranged from 3.02%to 49.24%.Five QTLs associated with C18:2 in rapeseed was detected,which located on linkage group A4,A5 and C4,and explained the phenotypic variation 4.16%to 59.23%.Six QTLs associated with C18:3 in rapeseed were detected,which located on linkage group A1,A4 and C4,and explained the phenotypic variation ranged from 2.8%to 33.37%.Two QTLs associated with C20:1 in rapeseed were detected,which located on linkage groups Al and C5,and explained the phenotypic variation ranged from 8.76%to 10.90%.One QTL associated with C22:1 in rapeseed was detected,which located on linkage group C2,and explained the phenotypic variation 7.80%.Three QTLs associated with oil content in rapeseed were detected,which located on linkage groups A1 and C3,and explained the phenotypic variation ranged from 5.54%to 6.48%. |
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