Molecular mapping and candidate gene analysis for yellow fruit flesh in cucumber

Abstract

Vitamin A deficiency is a major health problem in many countries around the world. Efforts to alleviate this have included adding supplements to wheat and maize flour. China produces over 70 % of the world production of cucumbers, and any attribute that could increase the β-carotene content of the fruit has the potential to have a major impact on world health. Cucumbers with yellow flesh contain larger amounts of β-carotene than those with white and green flesh. In this study, yellow fruit flesh cucumber inbred line PI200815 and white fruit flesh inbred line 931 were used as parents to construct a population for genetic analysis of cucumber fruit flesh color. The F2 segregating population was analyzed by the bulked segregant analysis method and SSR analysis with 2,112 pairs of SSR primers to build a genetic map using JoinMap 4.0 to map the yellow fruit flesh gene. The results showed that the yellow fruit flesh trait of PI200815 was controlled by a single recessive gene, namely yf. A total of 12 SSR primers and five Indel markers were used to build a molecular marker linkage group. The yf gene was mapped to cucumber chromosome 7 (Chr. 7). The closest flanking markers linked to yf were yfSSR108 and yfIndel29 with genetic distances of 0.6 and 0.3 cM, respectively. The physical distance for the region harboring yf was 149.0 kb with 21 predicted candidate genes. The accuracy of marker-assisted selection breeding using the molecular markers, yfSSR108 and yfIndel29, was 92.3 and 84.6 %, respectively.