Pochonia chlamydosporia Induces Plant-Dependent Systemic Resistance to Meloidogyne incognita

Abstract

<i>Meloidogyne</i> spp. are the most damaging plant parasitic nematodes for horticultural crops worldwide. <i>Pochonia chlamydosporia</i> is a fungal egg parasite of root-knot and cyst nematodes able to colonize the roots of several plant species and shown to induce plant defense mechanisms in fungal-plant interaction studies, and local resistance in fungal-nematode-plant interactions. This work demonstrates the differential ability of two out of five <i>P. chlamydosporia</i> isolates, M10.43.21 and M10.55.6, to induce systemic resistance against <i>M. incognita</i> in tomato but not in cucumber in split-root experiments. The M10.43.21 isolate reduced infection (32-43%), reproduction (44-59%), and female fecundity (14.7-27.6%), while the isolate M10.55.6 only reduced consistently nematode reproduction (35-47.5%) in the two experiments carried out. The isolate M10.43.21 induced the expression of the salicylic acid pathway (<i>PR-1</i> gene) in tomato roots 7 days after being inoculated with the fungal isolate and just after nematode inoculation, and at 7 and 42 days after nematode inoculation too. The jasmonate signaling pathway (<i>Lox D</i> gene) was also upregulated at 7 days after nematode inoculation. Thus, some isolates of <i>P. chlamydosporia</i> can induce systemic resistance against root-knot nematodes but this is plant species dependent.