Morphological and molecular characterization of new melon germplasm resistant to Podosphaera xanthii

Powdery mildew, mainly caused by the biotrophic fungus Podosphaera xanthii, is a devastating disease of cucurbits worldwide. The development of resistant cultivars is the main strategy to control this disease. The objective of the present work was the evaluation of melon accessions for resistance to P. xanthii. In the first experiment, forty-one melon accessions from different geographical origins were evaluated using artificial inoculation, under greenhouse conditions in Valencia, Spain. In the second experiment, fifteen melon accessions were evaluated for resistance in Mossoro, Rio Grande do Norte State, Brazil. The resistant accessions AC-02, AC-09, AC-15, AC-34, and AM-55 were characterized for morphological traits and microsatellites markers. The accessions AC-02, AC-09, AC-15, and AC-34 exhibited characteristics of the botanical variety momordica, while the accession AM-55 exhibited characteristics of the botanical variety acidulus. The molecular characterization confirmed the results observed in morphological characterization. The accessions identified could be useful as sources of resistance in breeding programs against P. xanthii in Brazil and Spain.