Nematicidal actions of the marigold exudate α-terthienyl: oxidative stress-inducing compound penetrates nematode hypodermis.

α-terthienyl is an allelochemical derived from the roots of marigold ( spp.), which is used to suppress plant parasitic nematodes. We investigated the nematicidal activity of α-terthienyl against the model organism and the root-knot nematode, As reported previously, α-terthienyl action was much higher after photoactivation, but was still effective against dauer larvae and second stage juveniles, even without photoactivation. Expression induction of two major enzymes, glutathione S-transferase (GST) and superoxide dismutase (SOD), was restricted in hypodermis following treatment with α-terthienyl. The susceptibility of nematodes to α-terthienyl changed when the expression of GST and SOD was induced or suppressed. From these results, under dark conditions (without photoactivation), α-terthienyl is an oxidative stress-inducing chemical that effectively penetrates the nematode hypodermis and exerts nematicidal activity, suggesting high potential for its use as a practicable nematode control agent in agriculture.