Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2007
Publication Date: 7/28/2007
Citation: Cuevas, H.E., Staub, J.E., Simon, P.W., McCreight, J.D., Zalapa, J.E. 2007. Carotenoid pathway genes and accumulation of B-carotene in Cucumis melo L [abstract]. American Society for Horticultural Science 104th Annual Conference. 42(4):1013-1014. Interpretive Summary:
Technical Abstract: Melon (Cucumis melo L.) is an important horticultural crop worldwide. In the United States, the orange-fleshed, U.S. Western Shipping and Eastern market type cantaloupes are economically important. Although cantaloupes are source of ß-carotene (precursor of vitamin A) with more than 80% of the carotenoids being produced in the fruit, this trait has not been adequately exploited for commercial production. The carotenoid biosynthetic pathway is known, but the inheritance and regulation of carotenogenesis is complex and poorly understood. Thus, 81 melon recombinant inbred lines (RIL) derived from ‘Top Mark’ (U.S. Western shipping type inbred line) and USDA inbred line 846-1 were evaluated in two contrasting environments, California (CA) and Wisconsin (WI) in two years. Four major carotenoid genes (Phytoene synthase, Zeaxanthin epoxidase, Violaxanthin de-epoxidase, and ß-carotene hydroxilase) were mapped and evaluated as candidate genes. Statistical analyses and composite interval mapping detected five quantitative trait loci (QTL), genetic by environments interactions and epistatic interactions, where four QTL were location specific (two for CA and two for WI), and one was location independent. Two QTL were in the same linkage group which carries the ß-carotene hydroxilase gene, although the estimated distances from QTL and these genes ranged from 43cM to 68 cM. California results indicated that fruit carotene concentration has a broad-based heritability (h2) of 0.50 and that three QTL explained 53% of the observed phenotypic variation (R2 total = 0.53). In Wisconsin, the trait h2 = 0.71 and the three QTL explained 44% of the phenotypic variation (R2 total = 0.44). Two-year results demonstrated that parental and melon RIL performance varies with growing environment.