Development and Evaluation of a New Source of Tolerance to Fusarium Wilt Race 1.2 in Melon

Abstract

Melon Fusarium wilt, caused by Fusarium oxysporum f. sp. melonis (Fom), is one of the most prevalent fungal diseases affecting melon (Cucumis melo L.). We aimed at finding an effective resource for breeding cultivars tolerant to Fom race 1.2, which includes pathotypes that cause yellowing (race 1.2y) and wilting (race 1.2w). We screened 294 melon accessions that originated mainly in Africa and Asia for tolerance to race 1.2y. The highest level of tolerance was observed in the Indian accession PI124550; one of the five PI124550 plants tested showed no disease symptoms. From this plant, a tolerant inbred line, YR01, was developed after seven rounds of selfing combined with selection for tolerance to race 1.2y. YR01 had a high level of tolerance not only to race 1.2y, but also to race 1.2w. It was more tolerant to race 1.2y than the tolerant reference control ‘Isabelle’ and was equally tolerant to race 1.2w. Analysis of F1 hybrids and an F2 population developed by crossing YR01 with susceptible ‘Earl’s Favorite Harukei 3’ suggested that YR01 had multiple recessive and dominant (or codominant) genes for tolerance to race 1.2y and one dominant gene for tolerance to race 1.2w. These results indicate that PI124550 and its derivative YR01 are a promising breeding material with novel genes conferring practically useful tolerance to both pathotypes of race 1.2.