Fine mapping and identifying candidate gene of Y underlying yellow peel in Cucurbita pepo

Abstract

As a conspicuous trait, peel color is one of the most important characteristics that affects commodity quality and consumer preferences. The locus Y underlying yellow peel in Cucurbita pepo (zucchini) was first reported in 1922; however, its molecular mechanism is still unknown. In this study, a genetic analysis revealed that yellow peel is controlled by a single dominant genetic factor. Furthermore, Y was mapped in a ~170 kb region on chromosome 10 by bulked segregated analysis (BSA) and fine mapping in F2 and BC1 segregating populations. The candidate region harbors fifteen annotated genes, among which Cp4.1LG10g11560 (CpCHLH) is regarded as a promising candidate gene. CpCHLH encodes a magnesium chelatase H subunit involved in chlorophyll biosynthesis, and its mutation can result in a reduction in chlorophyll content and yellow phenotype. Interestingly, a large fragment (~15 kb) duplication containing incomplete CpCHLH was inserted in the candidate interval, resulting in two reformed CpCHLH proteins in the yellow parental line. It is most likely that the reformed CpCHLH proteins act as a malfunctional competitor of the normal CpCHLH protein to interrupt the formation of chlorophyll. Overall, the isolation of Y will shed light on the molecular mechanism of the peel color regulation of zucchini and lay a foundation for breeding.

Effects of different light intensity on leaf color changes in a Chinese cabbage yellow cotyledon mutant

“…The expression of NCED gene in ginkgo was increased in yellow leaves in autumn, while decreased in green leaves in summer ( Sun et al., 2022 ). Previous studies in zucchini reported that NCED and CCD genes were downregulated in yellow and orange peels, which was agreement with the accumulation of yellow lutein ( Obrero et al., 2013 ; Niu et al., 2023 ). These evidences suggest that the differential expression of carotenoid-related genes combining the alteration of carotenoid content favor the leaf color changes in yellow cotyledon mutant 19YC-2.…”

“…A yellow-green leaf mutant of strawberry ( Fragaria pentaphylla ) was reported to be attributed to the gene mutation of CHLI , which resulted in lower chlorophyll level in mutant ( Ma et al., 2023 ). The mutation of CHLH in zucchini ( Cucurbita pepo ) caused the decrease in chlorophyll content and exhibited yellow peel phenotype ( Niu et al., 2023 ). Virus-induced gene silencing of CHLI and CHLD in pea ( Pisum sativum ) led to the decrease in chlorophyll content and abnormal chloroplast structure and showed yellow leaf phenotype ( Luo et al., 2013 ).…”