Analysis Of QTLs With Epistasic Effects For The Bolting Trait In Brassica Rapa Basing On CSSL

Bolting is an agriculturally important trait in Brassica rapa crops.Epistatic effects are caused by the interaction of non allelic genes.Epistasis is one of main genetic components on complex quantitative traits,and it has important influence on bolting of Chinese cabbage.In this study,5 chromosome single segment substitution lines and their corresponding recurrent parent,RcBr were used as the test materials to study epistasis effect between QTL.The 10 double fragment polymerization system was constructed by the half rounds to analysis of epistatic interaction effect.The results were as follows:1.In this study,14 CSSLs are screened from 142 CSSLs population basing on the results of QTL mapping in F2,RIL and CSSLs populations.14 CSSLs as test materials are used for the validation experiment.Finally,5 SSSLs were used as test materilas for epistatic interaction.There were two QTLs(qBI-7-1 and qBI-7-2)controlling BI were identified on A07 linkage groups;three QTLs(qFT-2-1,qFT-7-1 and qFT-8-1)controlling FT were identified on A02,A07 and A08 linkage groups.2.In the present study,we choose 10 double segment pyramiding lines by marker-assisted selections,developed from 5 single segment substitution lines with the same genetic background RcBr,to analysize the interactions of QTLs.On WD3(16swd001/16swd007):qFT-2-1 from 16swd001 was epistatic to qFT-7-1 from 16swd007.On WD4(16swd001/16swd009):qFT-2-1 from 16swd001 was epistatic to qFT-8-1 from 16swd009.On WD10(16swd007/16swd009):compared the effect of the pyramiding WD10(16swd007/16swd009)and two parents(16swd007 and 16swd009)flowering time,found the flowering time is almost the same.Therefore,it can be judged that there is no superposition effect between the two QTLs,can not determine whether there is interaction effect.3.Comparing with the results of the construction with the same parent RIL population to bolting traits location.In the two study,epistasis effect was detected between QTLs loci controlling bolting traits,but two QTLs loci with epistatic effects were different.In this study,a total of two pairs of QTLs showed significant epistatic effects for FT bolting indices.The two pairs of epistatic QTLs for FT between qFT-2-1 X qFT-7-1 and qFT-2-1×qFT-8-1.