ROLE OF 2,4-DIACETYLPHLOROGLUCINOL IN THE INTERACTIONS OF THE BIOCONTROL PSEUDOMONAD STRAIN F113 WITH THE POTATO CYST-NEMATODE GLOBODERA-ROSTOCHIENSIS

The potato cyst nematode Globodera rostochiensis is an important pest of potato (Solanum tuberosum). Pseudomonas fluorescens F113, which pro duces 2,4-diacetylphloroglucinol (DAPG),was investigated as a potentia l biocontrol agent against G. rostochiensis. Exposure of nematode cyst s to the pseudomonad, under in vitro conditions or in soil microcosms, almost doubled the ability of the eggs to hatch, The percentage of mo bile juveniles mas reduced threefold following their incubation in the presence of the pseudomonad, both in vitro and in soil. Results obtai ned with a transposon-induced DAPG-negative biosynthetic mutant of F11 3 and its complemented derivative with restored DAPG synthesis showed that the ability of strain F113 to produce DAPG was responsible for th e increase in hatch ability and the reduction in juvenile mobility, Si milar effects on egg hatch ability and juvenile mobility of G. rostoch iensis were obtained in vitro by incubating nematode cysts and juvenil es, 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.