Variability among Fusarium oxysporum f.sp. lycopersici isolates in their ability to interact with Meloidogyne incognita race 1

摘要

The study of the disease complex between the nematode Meloidogyne incognita and the fungus Fusarium oxysporum f.sp. lycopersici, causal agents of root-knot and fusarium wilt of tomatoes, respectively, has led to conflicting results. Reported effects of the complex include both increased severity or incidence of wilt symptoms on susceptible tomato cultivars as well as an ability of the fungus to overcome monogenic resistance in the presence of nematodes. However, other studies have reported a lack of such effects. Eleven F. oxysporum f.sp. lycopersici isolates obtained from different locations were studied to determine if different populations of this fungus varied in their ability to form a disease complex with the root-knot nematode. All race 1 isolates of Fusarium oxysporum f.sp. lycopersici were similar in being unable to overcome monogenic resistance in tomato during coinfection with nematodes. Isolates were also similar in causing a greater severity of wilt and vascular discoloration during coinfection of tomato with nematodes. Individual isolates differed with regard to the increase in wilt symptom severity and extent of vascular discoloration induced during coinfection, suggesting possible heterogeneity among F. oxysporum populations in the degree of interaction with Meloidogyne incognita.