RESISTANCE AGAINST THE POTATO CYST-NEMATODE GLOBODERA-PALLIDA SYSTEMICALLY INDUCED BY THE RHIZOBACTERIA AGROBACTERIUM-RADIOBACTER (G12) ANDBACILLUS-SPHAERICUS (B43)

Bacillus sphaericus strain B43 and Agrobacterium radiobacter strain G1 2, selected from the potato rhizosphere, significantly reduced Globode ra pallida juvenile penetration into potato roots. To better understan d the basis of antagonism, the mode-of-action of the bacterial antagon ists was investigated. The ability of the rhizobacteria to stimulate i nduced systemic resistance against the nematode was demonstrated in sp lit-root-trials, where the root system of a single potato plant was sp atially divided into two separate parts. Induced systemic resistance i n the split root system was caused by live and heat-killed bacterial c ells of both bacteria strains. Culture filtrates of B43 had the same e ffect but G12-culture filtrates did not. Therefore, it was not possibl e to demonstrate the presence on the leaf surface of a basipetal syste mic mechanism affecting the root system. (C) Orstom/Elsevier, Paris.