Oral Presentation Australasian Plant Pathology Society Conference 2025

Multiple Rhizobiaceae Causing Crown-Gall-Like Symptoms in Australian Wine Grapevines (119839)

Toni A Chapman 1 , Lauren Clackson 1 , Penny Flannery 1 , Perrine Portier 2 , Geraldine Taghouti 2 , Susan Austin 1 , Wendy Forbes 1 , Aida Ghalayini 1 , William Benson 1 , Ossie Wildman 1 , Sam Williamson 1 , Thalita Dal Toe Benica 1 , Fridtjof Snijders 1 , John Webster 1
  1. NSW Department of Primary Industries and Regional Development, Menangle, NSW, Australia
  2. CIRM-CFBP, INRAE, Beaucouze cedex, Angers, France

Allorhizobium vitis is the primary causative agent of crown gall in grapevines worldwide. In October 2023, several grapevine samples exhibiting typical crown/cane gall symptoms were submitted for diagnostic confirmation. Various bacteriological media and molecular assays were employed to isolate A. vitis. However, A. vitis was not detected in any of the collected samples. Instead, multiple Rhizobiaceae species were isolated and identified from infected samples. Selected isolates from each species underwent further analysis to assess their tumorigenic potential. Inoculation on carrot disks revealed several species capable of tumour formation. These tumorigenic isolates were then inoculated into sunflowers and grapevines to evaluate their ability to induce crown/cane galls. This study demonstrated that six different Rhizobiaceae species can cause crown-gall-like symptoms in grapevines.