Characterization of Agrobacterium vitis Strains Isolated from Feral Vitis riparia

Area of Science:

• Plant pathology
• Microbiology
• Genetics

Background:

• Agrobacterium vitis is a plant pathogen causing crown gall disease in grapevines.
• Feral grapevines can act as reservoirs for plant pathogens.
• Understanding pathogen diversity is crucial for disease management and biological control strategies.

Purpose of the Study:

• To isolate and characterize Agrobacterium vitis strains from feral Vitis riparia.
• To assess the genetic diversity and pathogenic potential of these strains.
• To evaluate their potential for biological control of grapevine crown gall.

Main Methods:

• Isolation of bacteria from Vitis riparia root samples.
• DNA fingerprinting using the region between 16S and 23S rRNA genes.
• Physiological characterization, including tartrate utilization.
• Tumorigenicity assays and hybridization with T-DNA probes.
• Plasmid profiling and biological control assays against a known pathogen strain.

Main Results:

• Agrobacterium vitis was isolated from 62% of feral Vitis riparia vines.
• DNA fingerprinting revealed high strain diversity, with 15 distinct profiles from 24 isolates.
• Most strains were non-pathogenic, lacked T-DNA, and did not utilize octopine/nopaline.
• A significant proportion of isolates did not utilize tartrate, a common characteristic of A. vitis.
• Seven isolates demonstrated significant inhibition of a tumorigenic A. vitis strain, comparable to a known biocontrol agent.

Conclusions:

• Feral Vitis riparia populations in New York harbor genetically diverse and largely non-pathogenic Agrobacterium vitis strains.
• These novel strains represent a distinct genetic lineage compared to previously identified tumorigenic strains.
• Several isolated strains exhibit promising biological control capabilities against grapevine crown gall, warranting further investigation.