Variation in melon (Cucumis melo) landraces adapted to the humid tropics of southern India

We present here the first comprehensive genetic characterization of melon landraces from the humid tropics of southern India. The genetic diversity among 50 melon landraces collected from 3 agro-ecological regions of southern India (6 agro-ecological sub-regions) was assessed by variation at 17 SSR loci, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance, biochemical composition (ascorbic acid, carotenoids, titrable acidity) and mineral content (P, K, Fe, Zn). Differences among accessions were observed in plant and fruit traits. Melon germplasm with high titrable acidity, higher than average amounts of mineral content and resistance to Cucumber mosaic virus, Zucchini yellow mosaic virus, powdery mildew (races 1, 2, 3, 5), Fusarium wilt (races 1, 2), Aphis gossypii and leafminer was recorded in the collection. A high level of genetic variability in melon germplasm was suggested by the SSR analysis. Comparative analysis using SSRs of the genetic variability between Indian melons from north, south, and east regions and reference accessions of melon from Spain, France, Japan, Korea, Iraq, Zambia showed regional differentiation between Indian melon accessions and that Indian germplasm was weakly related to the melon accessions from other parts of the world, suggesting that an important portion of the genetic variability found within this melon collection has not been used yet for the development of new cultivars. Additional collections of acidulus melon germplasm should be made in southern India and adequate management of this important genetic resource is clearly a necessity.