Phyllosphere colonization strategies related to successful infection in Xanthomonas vesicatoria

ROMERO AM; FELIPE V; MONTECCHIA MS; BIANCO MI; YARYURA PM

Boston

Congreso; International Congress of Plant Pathology (ICPP) 2018: Plant Health in A Global Economy; 2018

The American Phytopathological Society

Bacterial spot, induced by Xanthomonas vesicatoria, is a serious constrain of field grown tomatoes in Argentina. To better understand strainsaggressiveness, several characteristics of three local strains that induce different levels of disease were evaluated. For each strain, we determined in vitroswarming and twitching motilities, biofilm formation, xanthan production and xanthan viscosity. All assays were performed in triplicate. We alsoevaluated the number and size of the lesions induced by each strain and bacterial multiplication in planta; in both cases we used four plants per strain.Strain BNM208 was the most aggressive: it induced more and bigger lesions than BNM216; BNM214 showed intermediate values. When inoculated byinfiltration, avoiding the need for phyllosphere colonization, all strains reached similar population sizes. Among the strains evaluated, BNM208presented the greatest swarming and twitching motilities. BNM 208 also developed a mature biofilm with presence of defined cell clusters, ahomogeneous and compact structure, and higher biomass and substratum coverage than BNM214 and BNM216. The three strains produced similaramounts of xanthan, however, BNM208 produced the most viscous polysaccharide, which possibly relates to the better characteristics of its biofilm. Theability of BNM208 to move over surfaces and form mature biofilms may allow a better colonization of the phyllosphere, resulting in a high infectionsuccess of this strain.