Genetic Analysis And Qtl Mapping For β-carotene Content In Melon (Cucumis Melo L.) Flesh

Melon (Cucumis melo L.) which is one of the most important vegetable crops has abundantnutrition. During fruits development, change of fruit color is chiefly because of the presence of typicalcarotenoids and the relative content of specific pigments. β-carotene as one of the most importantcarotenoids in melon with orange flesh plays essential functions to human health.In this study, the content of β-carotene of six different melon cultivars (387,389,390,391,392,393) was detected during fruit development to study the dynamic changes of the content, for harvestreference at the best time; six generations (P1、P2、F1、B1、B2and F2) were derived from a cross of“200932” and “200930”, these two species have great differences in fruit color. The content ofβ-carotene of the six generations was detected using HPLC to study the inheritance of melon β-carotenecontent traits by joint analysis method of multiple generations; a genetic map enriched for β-carotenecontent was constructed, using a F2generation to analysis the QTL. These results were useful for betterunderstanding the inheritance rule of β-carotene and molecular assisted breeding. The results showedbelow:1. The content of β-carotene of six different melon cultivars (387,389,390,391,392,393) wasdetected during fruit development. The result indicated that the dynamic variation of β-carotene contentduring fruit development varies with flesh color. The content of β-carotene in cultivars which flesh colorturned green to white (391), between white and green (393) and still green (392) changed relatively flatduring fruit development while the content of β-carotene in cultivars which flesh color turned green todark orange (389) and orange (390、387) showed the trend of increase then remain stable.2. Six generations (P1、P2、F1、B1、B2and F2) derived from a cross of “200932”(orange flesh) and“200930”(green flesh) were used to study the inheritance of melon β-carotene content traits by jointanalysis method of multiple generations. The results showed that β-carotene content fitted two pairs ofadditive-dominance-epitasis major genes plus additive-dominant polygene (E-1model). The major geneheritability of F2population was92.66%and the polygene heritability was5.40%; the major geneheritability of B1population was86.80%and the polygene heritability was0; the major gene heritabilityof B2population was59.88%and the polygene heritability was38.60%.3. A genetic map enriched for β-carotene content was constructed using a F2population developedfrom a cross of two species “200932” and “200930”, which have great differences in fruit color. Themap included154SSRs, of which77were newly developed from fruit ESTs. The genetic map consistedof17linkage groups spanning1663.5cM with an average of10.8cM between markers. Total threeQTLs for β-carotene content were detected. These QTLs were mapped on linkage groups1,4(Chr4),7(Chr7) respectively. Two QTLs explained phenotypic variation more than15%. The QTL β-car1whichwas mapped on the first linkage group explained up to26.9%of the phenotypic variances.