Biological Control for Grapevine Crown Gall Evaluated by a Network Meta-Analysis

Abstract

Grapevine crown gall (GCG), which is caused by Allorhizobium vitis (=Rhizobium vitis) tumorigenic strains, is the most important disease of grapevine around the world. Previously, nonpathogenic A. vitis strains VAR03-1, ARK-1, ARK-2, and ARK-3 were identified as promising biological control agents, but the control effects of each strain were not directly compared and assessed in the field because field trials were conducted in different fields and years. Thus, the results of the control effects obtained from 16 field trials in 12 years from 2006 to 2017 were analyzed and evaluated by a linear mixed model (LMM) and a network meta-analysis (NMA). The results of the LMM strongly indicate that the factor “antagonistic strain” was significantly related to the biological control activity in this study, but the other factors, “concentration of cell suspension”, “field”, and “year”, were not. Then, the results of 16 field trials were combined in an NMA. The estimated relative risk (RR) after treatment with ARK-1, ARK-2, ARK-3, VAR03-1, and K84 were 0.16, 0.20, 0.22, 0.24, and 0.74, respectively. In conclusion, strain ARK-1 was the best antagonist regardless of the concentration of the cell suspension, field, and year differences, and it can be recommended to control GCG.

Insight into the population dynamics of pathogenic bacteria causing grapevine crown gall in snowfall areas: snow cover protects the proliferation of pathogenic bacteria

“…R. rhizogenes strain K84 inhibits gall formation caused by tumorigenic R. rhizogenes (New and Kerr, 1972;Kerr and Htay, 1974;Kerr, 1980;Kerr and Bullard, 2020), but it is not effective against GCG caused by TAV (Burr et al, 1998;Kawaguchi et al, 2007;. Previously, we reported that nonpathogenic AV strains VAR03-1 and ARK-1 reduced gall occurrence not only in grapevines but also in several other plant species (Kawaguchi et al, 2007;Kawaguchi et al, 2008;Kawaguchi, 2009;Kawaguchi, 2013;Kawaguchi, 2014;Kawaguchi et al, 2015;Kawaguchi et al, 2017;Saito et al, 2018;Noutoshi et al, 2020;Wong et al, 2021;Kawaguchi, 2022c;Kawaguchi et al, 2023). Strain ARK-1, in particular, exhibited strong activity in controlling GCG in many vineyards and has some unique biocontrol mechanisms.…”