hydrogen cyanide produced by pseudomonas chlororaphis o6 exhibits nematicidal activity against meloidogyne hapla

Root-knot nematodes (meloidogyne spp.) are parasites that attack many field crops and orchard trees, and affect both the quantity and quality of the products. a root-colonizing bacterium, pseudomonas chlororaphis o6, possesses beneficial traits including strong nematicidal activity. to determine the molecular mechanisms involved in the nematicidal activity of p. chlororaphis o6, we constructed two mutants; one lacking hydrogen cyanide production, and a second lacking an insecticidal toxin, fitd. root drenching with wild-type p. chlororaphis o6 cells caused juvenile mortality in vitro and in planta. efficacy was not altered in the fitd mutant compared to the wild-type but was reduced in both bioassays for the mutant lacking hydrogen cyanide production. the reduced number of galls on tomato plants caused by the wild-type strain was comparable to that of a standard chemical nematicide. these findings suggest that hydrogen cyanide-producing root colonizers, such as p. chlororaphis o6, could be formulated as “green” nematicides that are compatible with many crops and offer agricultural sustainability.