Role of 2,4-Diacetylphloroglucinol in the Interactions of the Biocontrol Pseudomonad Strain F113 with the Potato Cyst Nematode Globodera rostochiensis

Abstract

The potato cyst nematode Globodera rostochiensis is an important pest of potato (Solanum tuberosum). Pseudomonas fluorescens F113, which produces 2,4-diacetylphloroglucinol (DAPG), was investigated as a potential biocontrol agent against G. rostochiensis. Exposure of nematode cysts to the pseudomonad, under in vitro conditions or in soil microcosms, almost doubled the ability of the eggs to hatch. The percentage of mobile juveniles was reduced threefold following their incubation in the presence of the pseudomonad, both in vitro and in soil. Results obtained with a transposon-induced DAPG-negative biosynthetic mutant of F113 and its complemented derivative with restored DAPG synthesis showed that the ability of strain F113 to produce DAPG was responsible for the increase in hatch ability and the reduction in juvenile mobility. Similar effects on egg hatch ability and juvenile mobility of G. rostochiensis were obtained in vitro by incubating nematode cysts and juveniles, respectively, in the presence of synthetic DAPG. DAPG-producing P. fluorescens F113 is proposed as a potential biocontrol inoculant for the protection of potato crops against the potato cyst nematode.

Bacteria used in the biological control of plant-parasitic nematodes: populations, mechanisms of action, and future prospects

“…towards plant-parasitic nematode species belonging to the genera Meloidogyne, Heterodera and Rotylenchulus (Gokta & Swarup, 1988;Kloepper et al, 1992;Madamba et al, 1999;Siddiqui & Mahmood, 1999;Insunza et al, 2002;Kokalis-Burelle et al, 2002;Meyer, 2003;Giannakou & Prophetou-Athanasiadou, 2004;Li et al, 2005). Rhizosphere Pseudomonas strains also exhibit diverse pathogenic mechanisms upon interaction with nematodes (Spiegel et al, 1991;Kloepper et al, 1992;Kluepfel et al, 1993;Westcott & Kluepfel, 1993;Cronin et al, 1997a;Kerry, 2000;Jayakumar et al, 2002;Andreogloua et al, 2003;Siddiqui et al, 2005). The mechanisms employed by some Pseudomonas strains to reduce the plantparasitic nematode population have been studied.…”

Non-target effects of bacterial biological control agents suppressing root pathogenic fungi

“…F113, as well as synthetic DAPG, is known to increase egg hatching of the root pathogenic nematode Globodera rostochiensis, but to reduce the mobility of the juveniles [61]. The reduced juvenile mobility suggests that survival conditions are suboptimal, while increased egg hatching would potentially increase nematode attack on plants.…”

Genetic diversity and biocontrol potential of fluorescent pseudomonads producing phloroglucinols and hydrogen cyanide from Swiss soils naturally suppressive or conducive to Thielaviopsis basicola-mediated black root rot of tobacco

“…In one such strain, designated CHA0, hydrogen cyanide (HCN) and 2,4-diacetylphloroglucinol (Phl; Keel et al, 1992) have been shown to be major determinants of the strain's biocontrol ability. HCN and, especially, Phl are also implicated in the biological control of soil-borne phytopathogens by other antagonistic fluorescent pseudomonads (Vincent et al, 1991;Fenton et al, 1992;Keel et al, 1992;Cronin et al, 1997;Ellis et al, 2000;Haas & Keel, 2003;Moënne-Loccoz & Défago, 2004). In addition, Phl 1 pseudomonads and Phl synthesis contribute to the monoculture decline of take-all disease of wheat caused by Gaeumannomyces graminis var.…”