基于遗传距离和配合力预测辣椒辣度杂种优势

Prediction of heterosis of pepper(Capsicum annuum L.)pungency degree based on genetic distance and combining ability

  • 摘要: 【目的】 利用简化基因组测序(GBS)技术估算辣椒亲本间的SNP遗传距离,并通过配合力分析,预测杂交后代辣度相关性状的杂种优势,为高辣度辣椒新品种的亲本选配及杂种优势利用提供理论依据。【方法】 选取11个辣椒自交系为亲本材料(母本A1~A5,父本B1~B6),采用不完全双列杂交法(NCⅡ)配制30个杂交组合,对亲本及杂交组合的5个辣度相关性状[二氢辣椒素、辣椒素、辣椒素总量、斯科维尔指数(SHU)和辣度]进行测定,并对各性状的SNP遗传距离、配合力和杂种优势间的相关分析。【结果】 通过Illumina测序共获得20.0 Gb原始数据,有效数据为19.9 Gb,Q20平均97.3%,平均GC含量36.59%;通过比对共获得1671621个SNP位点,1732641个SNP变异位点;11份辣椒亲本材料间的遗传距离为0.0299~0.4762。辣椒各辣度相关性状普遍存在杂种优势,A5×B6的二氢辣椒素、A5×B1的辣椒素及A5×B3的辣椒素总量、SHU和辣度杂种优势最明显。不同亲本的不同辣度相关性状间的一般配合力(GCA)效应值差异较大,其中A5的辣椒素和B6的二氢辣椒素具有较高的GCA效应值,二者配制的杂交组合A5×B6(二氢辣椒素)、A5×B1(辣椒素)的特殊配合力(SCA)效应值最高,表明亲本之一具有较高GCA效应值易组配出SCA效应值较高的杂种后代。各辣度相关性状的SCA与杂种优势均呈极显著正相关(P<0.01,下同),相关系数为0.466~0.782,而GCA与杂种优势相关性较弱或呈负相关;二氢辣椒素、辣椒素总量、SHU和辣度的杂种优势与SNP遗传距离均呈显著(P<0.05)或极显著正相关,相关系数为0.382~0.579。【结论】 利用SNP遗传距离和SCA预测辣椒辣度相关性状杂种优势是可行的,但还需考虑亲本间的GCA。因此,在对辣椒辣度相关性状杂交组合预测杂种优势时,可将配合力与遗传距离相结合,以配制辣度更高的杂交组合。

     

    Abstract: 【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 design. 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,combining 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 related 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 considerably 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 effect values contributed to high SCA effect values in their offspring. SCA showed an extremely significant positive correlation 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 correlated 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 considered. 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.

     

/

返回文章
返回