基于遗传距离和配合力预测辣椒辣度杂种优势OA北大核心CSTPCD

[Objective]This study aimed to estimate SNP genetic distances between pepper(Capsicum annuum L.)parents using genotyping-by-sequencing(GBS),and predict the heterosis of pungency-related traits in hybrid offspring through combining ability analysis,providing theoretical basis for the selection of parents and heterosis utilization in breeding new high-pungency varieties.[Method]A total of 30 hybrid combinations were generated using 11 pepper inbred lines(5 female parents,A1-A5,and 6 male parents,B1-B6)as parents in incomplete diallel cross(NCⅡ)mating de-sign.Five pungency related traits,including dihydrocapsaicin,capsaicin,total capsaicin content,Scoville heat unit(SHU)and pungency degree were evaluated in both parents and hybrids.Correlations among SNP genetic distance,com-bining ability,and heterosis for each trait were analyzed.[Result]A total of 20.0 Gb of original data,with 19.9 Gb of clean reads,were obtained by Illumina sequencing.The average of Q20 was 97.3%,and the average GC content was 36.59%.Through comparison,a total of 1671621 SNP loci and 1732641 SNP variant loci were obtained.The genetic dis-tances between the 11 parents ranged from 0.0299 to 0.4762.Heterosis was commonly observed for pepper pungency re-lated traits.The most obvious heterosis was observed in A5×B6 for dihydrocapsaicin,A5×B1 for capsaicin,and A5×B3 for total capsaicin content,SHU and pungency degree.General combining ability(GCA)effect values varied considerab-ly among different pungency related traits of different parents.Among them,A5 exhibited high GCA effect values for capsaicin,and B6 for dihydrocapsaicin.The hybrid combinations A5×B6(dihydrocapsaicin)and A5×B1(capsaicin)showed the highest specific combining ability(SCA)effect values,suggesting that one of the parents with high GCA ef-fect values contributed to high SCA effect values in their offspring.SCA showed an extremely significant positive correla-tion with heterosis for all pungency related traits(P<0.01,the same below),with correlation coefficients ranging from 0.466 to 0.782.However,GCA showed weak or negative correlations with heterosis.The heterosis for dihydrocapsaicin,total capsaicin content,SHU and pungency degree were significantly(P<0.05)or extremely significantly positively corre-lated with SNP genetic distance,with the correlation coefficients ranging from 0.382 to 0.579.[Conclusion]To predict heterosis for pungency related traits in pepper via SNP genetic distance and SCA is feasible,but GCA should also be con-sidered.Therefore,when predicting heterosis for pungency related traits in hybrid combinations,combining ability and genetic distance can be used together to develop higher-pungency hybrid combinations.