Isolation ofAgrobacterium tumefaciensBiovar 3 from Grapevine Galls and Sap, and from Vineyard Soil

Abstract

A. tumefaciens biovar 3 (AT 3) was isolated from grapevine galls, sap of bleeding vines, and from vineyard soil by using a selective medium. AT 3 was the predominant biovar isolated from galls. The bacterium was recovered from sap from 7 of 24 infected vines and one of 17 apparently healthy vines. Ten sap isolates were identified as AT 3 and all were pathogenic on grapevine and sunflower. Typical colonies (244) of Agrobacterium were selected from dilution plates from 30 vineyard soil samples. Five of these strains were pathogenic, 3 being AT 3 and 2 similar to A. tumefaciens biovar 1. Almost all of the AT 3 strains from galls, sap, and soil caused galls on tomato, sunflower and grapevine inoculated in greenhouse tests.