Mechanism of nematode infection by fungal antagonists, Purpureocillium lilacinum (Thom) Samson and Pochonia chlamydosporia (Goddard) Zare & Gams 2001

Plant parasitic nematodes are one of the major limiting factors in crop production. Root knot nematodes, Meloidogyne spp. have a wide host range and higher fecundity. Purpureocillium lilacinum and Pochonia chlamydosporia are beneficial fungi that parasitizes the eggs of root knot nematodes. Commercial formulations of these fungi are available in India and elsewhere. An in vivo study was carried out to understand the mode of action of these fungi. Conidial suspension of both P. lilacinum (isolate TNAU-Pl001) and P. chlamydosporia (isolate TNAU-Pc001) were prepared and inoculated on the egg masses. Fungal hyphae started attaching on the egg surface on the 1^st day after inoculation. Mycelial penetration on egg shell was initiated by approsorium formation on the 2^nd day and eggs were completely colonized by the 4^th day after inoculation. Egg contents were condensed and development stopped at gastrula stage itself. The phialids were flask shaped which formed on the 7^th day after inoculation. In P. chlamydosporia, the infection process was similar to P. lilacinum, except for the formation of chlamydospores which was observed both intercalary and terminal. Chlamydospores were observed 10–12 days after inoculation. The endophytic nature of P. chlamydosporia was also observed in paddy roots.