Influence of Fusarium wilt resistant tomato cultivars on root colonization of the mutualistic endophyte Fusarium oxysporum strain 162 and its biological control efficacy toward the root-knot nematode Meloidogyne incognita

Abstract

The ability of the nematode antagonistic, mutualistic endo-phyte Fusarium oxysporum strain 162, to colonize the endorhiza of different Fusarium wilt resistant and susceptible cultivars of tomato (Solanum lycopersicon L.) was investigated. The fungus colonized the endorhiza of both wilt resistant and susceptible cultivars of tomato. Colonization after 3 weeks ranged from 40% to 100% in trial 1 and from 32% to 75% in trial 2. Percent colonization declined 6 weeks after fungal inoculation in resistant as well as susceptible varieties. Biocontrol presented by nematode penetration in trial 1 and number of galls in trial 2 reached 82% and 55%, respectively. Surprisingly, the level of nematode control in Fusarium wilt resistant cultivars was found similar or even higher in some cases when compared to that in wilt susceptible cultivars. Although endophyte colonization decreased over time, the antagonistic fungus reduced Meloidogyne incognita infestation significantly in the majority of the cultivars tested.