Selection of in vitro propagated muskmelon plants with superior resistance to Fusarium oxysporum f. sp. melonis
Keywords:Cucumis melo, Disease resistance, Fusarium oxysporum f. sp. melonis, In vitro propagation, Latent pathogen, Temperature effect, Selection
AbstractThree genotypes of muskmelon (Cucumis melo L.), which were identified as resistant to the vascular wilt pathogen Fusarium oxysporum f. sp. melonis, were subjected to a rigorous selection process under conditions of low temperatures (av. 17.5°C). High disease incidence and breakdown of general resistance were observed in all the genotypes at this temperature. A few plants which survived this screening at the 28-day stage were carried forward through shoot-tip culture on semisolid Murashige and Skoog (MS) medium supplemented with 3% sucrose, 2 ppm kinetin, and 0.5 ppm mdole-3-acetic acid. The pathogen was found to be present in latent form in 77.8, 26.3, and 16.7% of these plants of the genotypes Chittidar, Harela, and IC 540, respectively, as evidenced by the growth of F. oxysporum on the MS culture medium. The remaining shoot-tip cultures, devoid of the latent pathogen, were carried forward and established ex vitro. This approach, comprising the several stages outlined, resulted in the selection of individual plants possessing higher levels of resistance to the pathogen than those of the base population.