Developmental and behavioural effects of the endophytic Fusarium moniliforme Fe14 towards Meloidogyne graminicola in rice

The root-knot nematode, Meloidogyne graminicola, is an important pest of rice in many rice production areas worldwide. The endophyte Fusarium moniliforme strain Fe14, isolated from a disinfected root of rice, has previously shown potential antagonistic activity against M. graminicola. This study shows the effects of Fe14 on M. graminicola behaviour, infection, development and reproduction. The endophyte Fe14 colonisation significantly reduced M. graminicola penetration into rice roots by 55% and increased the male to female ratio nine times. The endophyte also delayed juvenile development into female inside the rice root. These results suggest a suboptimal performance of the giant cell and a cumulative effect of the endophyte on the long-term root-knot nematode population development. In split-root assays, the application of Fe14 at the inducer side significantly reduced nematode invasion at the responder side by 38% and 60% in two independent trials. This result suggests a systemic effect of the endophyte on rice plants. The root exudates from Fe14-treated plants were either less attractive or had repellent effect on nematode movement. The results, when compared to what was described for other endophytic Fusarium against other nematode species, may indicate a basal response mechanism initiated in the plant by endophytic Fusarium spp. The present study may give leads for unravelling the molecular mechanisms responsible for the induced systemic defence responses in plants.