Mixed genetic analysis of major genes plus multiple genes in pepper fruit surface folds

<bold>Objective</bold> Screw pepper is one of the main consumption peppers in Chinese market.The wrinkles on the surface of screw pepper fruits not only enhances the layered appearance but also affects its growth and flavor to a certain extent.This study aims to explore the inheritance of wrinkles on the fruit surface of screw peppers，thus laying a foundation for the mapping of genes related to the wrinkles. <bold>Method</bold> In this study，using the Guangpi chili pepper A68 as the female parent and screw pepper M18 as the male parent，a four-generation genetic population（P₁，P₂，F₁，and F₂）was established.By investigating the fruit wrinkle rate and wrinkle number of each individual plant in each generation，the genetic model of major genes + polygenes for fruit surface wrinkle rate and wrinkle number in Luosi chili peppers was analyzed using the mixed genetic model analysis method proposed by Gai Junyi.Furthermore，the genetic effects and genetic parameters were estimated and calculated. <bold>Result</bold> The wrinkle rate and the number of wrinkles on the fruit surface of screw peppers conformed with the genetic characteristics of quantitative traits.Both traits fit the model of two pairs of additive-dominant-epistatic major genes + additive-dominant-epistatic polygenes（MX2-ADI-ADI）.For the wrinkle rate，the additive effect values of the two pairs of major genes were -0.997 2 and -0.498，and the dominant effect values -0.498 7 and -0.498 3.The interaction effect values of additive × additive，additive × dominant，dominant × additive，and dominant × dominant were -0.000 2，-0.000 2，0.498 3，and 0.498 3，with a major gene heritability of 79.49%.For the number of wrinkles，the additive effect values of the two pairs of major genes were -1.249 2 and -0.249 9，and the dominant effect values were -0.249 9 and -0.249 9.The interaction effect values of additive × additive，additive × dominant，dominant × additive，and dominant × dominant were 0.249 9，0.249 9，-0.749 4，and 0.249 2，with a major gene heritability of 92.29%.Considering the combined effects of additive and dominant loci of the two pairs of major genes，the relationship between the three effect sizes in the genetics of wrinkle rate and number of wrinkles on the fruit surface of screw peppers should be： interaction effect &gt; dominant effect &gt; additive effect. <bold>Conclusion</bold> The wrinkle rate and the number of wrinkles on the fruit surface of screw peppers are controlled by two pairs of additive-dominant-epistatic major genes + additive-dominant-epistatic polygenes.The heritability of the major genes for the wrinkle rate of screw pepper fruits is 79.49%，which is influenced to a certain extent by multiple minor genes and environmental factors.The heritability of the number of wrinkles on the fruit surface of screw peppers is 92.29%，which is less affected by environmental factors.