辣椒青熟期紫黑色果皮的主基因+多基因混合遗传分析

A mixed genetic analysis of major gene plus polygene for purplish-black pericarp at mature-green stage in pepper

【目的】果皮颜色是辣椒的重要农艺性状之一。旨在探究青熟期紫色辣椒果色遗传规律,为辣椒新品种选育和紫色辣椒呈色机制提供理论依据。【方法】研究以C152(青熟期紫黑色果皮)为母本、A37(青熟期绿色果皮)为父本,构建P_(1)、P_(2)、F_(1)、F_(2)4个世代遗传群体。细化青熟期果皮颜色分类,调查统计发育正常、达到商品成熟度的对椒果皮颜色。对所得数据进行正态分布检验,并联合分析4个世代获得遗传模型,计算各遗传模型的MLV值和有关成分分布参数,将MLV值转换为AIC值,选取遗传模型中AIC值最小的5个模型作为备选模型,对备选模型进行适合性检验,并获得统计量,选取显著统计量最少的备选模型作为最佳遗传模型,计算最佳遗传模型的一阶遗传参数,并由群体方差和有关成分分布方差估计出最佳遗传模型的二阶遗传参数。【结果】统计结果显示,F_(1)代为浅紫黑色,介于母本的紫黑色和父本的绿色之间,且更偏向于母本。F_(2)群体中颜色过渡丰富,性状变异呈连续状态。正态性检验结果表明,所得数据的中位数与众数为4,平均值为4.097,变异系数为49.38%,果色性状的峰度为-1.117,偏度为-0.321,两者绝对值在1.96之间,符合正态分布。一阶遗传参数中主基因加性效应值为2.5428、显性效应值为0.5352,主基因的显性度为0.2201。二阶遗传参数结果表明,群体表型的总方差为0.5626,主基因遗传方差为3.5299,多基因的遗传方差与遗传力均为0。群体的主基因遗传率为86.25%。【结论】辣椒青熟期果皮颜色紫黑色对绿色为不完全显性,紫黑色果皮受到一对加性-显性主基因+加性-显性-上位性多基因控制,主基因的加性效应与显性效应皆为正向,且加性效应强于显性效应。紫黑色果皮表现出极高的遗传力,性状决定受遗传因素较大。

[Objective]Pericarp skin color is one of the important agronomic traits of chili peppers.In order to investigate the genetic pattern of peel color and provide a theoretical basis for the selection and breeding of new varieties of purple peppers at the green stage of ripening,a study was conducted to determine the mechanism of color expression in purple peppers.[Method]C152(purplish-black pericarp at green ripening stage)was used as the female parent and A37(green pericarp at green ripening stage)was used as the male parent in this study.Genetic populations were constructed for four generations,P_(1),P_(2),F_(1),and F_(2).A more precise classification was conducted for peppers at the green ripening stage,the peel color was investigated and counted for those peppers that developed normally and reached commercial maturity.Normal distribution was tested for the obtained data,different genetic models were obtained by joint analysis among the four different generations,Maximum Likelihood Value(MLV)of the respective genetic models and parameters of the distribution of the components of interest were computed,MLV were converted into Akaike’s information criterion(AIC)values.The five models with the smallest AIC values in the genetic model were selected as the alternative models.The fitness test of the alternative models was conducted and the statistics were obtained.The alternative model with the least significant statistics was selected as the optimal genetic model.The first-order genetic parameters of the optimal genetic model were calculated,and the second-order genetic parameters of the optimal genetic model were estimated from the population variance and the distribution variance of the relevant components.[Result]The findings showed that the F_(1)generation was light purple black,which is between the purple black of the female parent and the green of the male parent,and it was more biased towards the female parent.Color transitions were abundant in the F_(2)population and the trait variation was continuous.The results of normality test showed that the median and the multitude of the obtained data were 4,the mean was 4.097,the coefficient of variation was 49.38%,the kurtosis of the fruit color trait was-1.117,the skewness was-0.321,and the absolute values of the two were in the range of 1.96,which was in line with the normal distribution.In the first order genetic parameters,the additive effect value of the main gene was 2.5428,dominant effect value was 0.5352 and dominance degree of the main gene was 0.2201.The results of the second order genetic parameters showed that the total variance of the population phenotypes was 0.5626,the genetic variance of the main genes was 3.5299,and the genetic variance of the polygenes and the heritability were 0.The heritability of the main genes in the population was 86.25%.[Conclusion]Purplish-black is incompletely dominant to green in green-ripe peppers;purplish-black pericarp is controlled by a pair of additive-dominant primary genes plus additive-dominant-superior polygenes,and the additive and dominant effects of the primary genes are both positive,and the additive effect is stronger than the dominant effect.Purplish-black pericarp shows a extremely high level of heritability,and the trait decision was influenced by genetic factors.