西葫芦淡绿色果皮形成规律的生理学及遗传学分析OA

[Objective]Peel color is an important commercial trait of zucchini(Cucurbita pepo L.),but few researches focus on the gene mapping of peel color at the commercial stage.This study aimed at physio-logical and genetic analyses of green fruit peels at varying types.[Methods]Cross-sections of zucchini fruits with different green peel colors were observed during the commercial stage.The contents of chlorophyll a,chlorophyll b,and carotenoids were measured at different developmental stages,and their sum was calculated to determine total pigment content.Colorimeter measurements were used to quantify peel color and define chlorophyll levels and ranges.Finally,a linkage population and BSA-seq technology were employed to prelimi-narily map the major-effect QTL for light green peel color in zucchini.[Results]Peel color was influenced by the outermost epi-dermal structure and the chlorophyll pigment layer.Photosynthetic pigment analysis revealed that at the commercial stage,the total pigment content in light-green peels decreased by 64.05%compared to 0 days after pollination,showing significant de-greening.While dark lime-green peels showed a significant increase in total pigment content,dark-green peels exhibited the highest overall content.At market maturity,chlorophyll a was the predominant pigment in light-green peels,accounting for 53%of the total content.Conversely,chlorophyll b was more prevalent in dark lime-green and dark-green peels,account-ing for 46%and 55%,respectively.Regarding the color difference index,the h* value increased progressively with green in-tensity,while the L*,b*,and C* values exhibited an inverse relationship with green depth.The a* value showed no significant variation among different fruit peels.Genetic analysis showed a 3∶1,segregation ratio,indicating that light-green peel was a dominant qualitative trait controlled by a single pair of alleles.BSA_seq analysis localized the gene responsible for light-green peel to physical intervals of 1.88 Mb and 0.8 Mb on chromosome 9.[Conclusion]This study demonstrated that the light-green peel in zucchini was a qualitative trait controlled by a single gene,primarily influenced by variations in chlorophyll a content,whereas dark lime-green and dark-green peels were primarily influenced by chlorophyll b.The preliminarily localization of this gene to chromosome 9 provided a foundation for the development of molecular markers and the identification of candidate genes.