The effect of Arbuscular Mycorrhizal Fungi (Glomus mosseae and G. intraradices) on pathogenicity of root-knot nematode (Meloidogyne javanica) and histopathological changes in infected tomato plant

The root-knot nematode، Meloidogyne javanica (Treub، 1885) is one of the most important pathogens in many crops، especially in tomato. Formation of giant cells by nematode is the most important histological changes in disease process. Two arbuscular mycorrhizal fungal species، Glomus mosseae and G. intraradices were used to study the effects of arbuscular mycorrhizal fungi on pathogenicity and histopathological changes of root-knot nematode، in a completely randomized design، performed in glasshouse. Fungi and nematode were propagated on white clover and tomato، respectively. Nematode-related factors and pathogenicity indices were evaluated، after the nematode completed three generations. Analysis of variance showed the positive effect of mycorrhizal fungi on nematode damages. Mean comparison of the number and size of giant cells were showing significant difference between mycorrhizal and non-mycorrhizal plants. Thus mycorrhizal fungi caused reduction in number and size of giant cells in plants infected with nematode، but decrese in juvenile development.