Genetic diversity assessment of wild melon accessions for drought adaptive traits

Abstract:

A paradox sits at the heart of melon improvement: cultivated varieties (Cucumis melo L.) have been bred for sweetness and size, yet the wild relatives that carry drought-survival genes are routinely ignored in breeding programmes. This research assessed genetic diversity and drought-adaptive traits in 48 wild melon accessions from seven countries, evaluated in a rain-out shelter at Evergreen State University of Agriculture, Pullman, Washington, during 2021 and 2022. Twenty SSR markers revealed high allelic richness (mean 6.3 alleles per locus) and moderate genetic differentiation (Fst = 0.18) among geographic groups. Phenotyping under progressive drought identified eight accessions with relative water content above 0.70 at −1.5 MPa soil water potential. Nei's genetic distance ranged from 0.12 to 0.78. Accessions from the Thar Desert (India) and Sonoran Desert (Mexico) clustered separately and carried the highest frequency of drought-tolerance alleles. These accessions are recommended as priority donors for introgressing drought resilience into commercial melon cultivars.