Isolation of non-pathogenic Agrobacterium spp. biovar 1 from agricultural soils in Slovenia

Abstract

The disease crown gall, which causes damage on perennial agricultural crops, is economically important in many countries. We therefore explored the presence of Agrobacterium spp. in a variety of agricultural soils where fruit trees are grown. Most samples were collected in four regions of Slovenia where a majority of fruit tree plantations are situated. Crown gall-affected plants were not observed on any of the sampling sites. Members of Agrobacterium spp. biovar 1 were isolated from 63 of the 72 soil samples (88%), but none from forest soil. All isolates of this Agrobacterium species complex were determined to be non-pathogenic by biotests and were assigned to genomic species based on a recA allele sequence analysis. Fourty-three isolates were allocated into genomic species G1 and 26 isolates into G4. Among both genomic species, new alleles of the recA gene were recognized: seven new alleles in G1 (denominated G1-15 to G1-21) and four in G4 (G4-7 to G4-10). Two alleles predominated among the Slovenian strains, recA-G1-15 and recA-G4-2. Different colony morphologies were observed between strains of G1 and G4 on KB medium.