Engineering plants for nematode resistance

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INTRODUCTION

Nematodes are obligate parasites
Obtain nutrition from plant cytoplasm
Species includes ectoparasites and endoparasites
Sedentary endoparasites of the family Heteroderidae cause most economic damage
Heteroderidae divided into 2 groups

Feeding habits of nematodes

Ectoparasitic nematodes
Live completely outside the plant
Migratory endoparasitic nematodes
Live completely inside the plant but move freely between the roots and soil
Sedentary endoparasitic nematodes
Live inside the plant but adult female becomes sedentary
Semi- endoparasitic nematodes
Part of body inside root. By movement when feeding

1.Strategies targeting directly the nematode

Exploit the structural difference between nematodes and plants
Eg:- chitin and collagen, both are important components of the nematode and absent in plants
Transgenic plants expressing chitinase and collagenase were constructed
Nematode resistant plants have not been reported so far


RESISTANCE MECHANISMS

In resistant tomatoes a localized necrosis, suggesting a HR is visible near the anterior end of the nematode within a few days of infection.
2. HI (Gpa2) mediated resistance of potato, the feeding site becomes surrounded by necrotic tissues and collapses.
3. HsIPro-I
Not involved in hypersensitive response. Nematode die in the last J2 stage. Because of degradation of the feeding structure(syncytium) in the host.