Virulence factors analysis of native isolates of Xanthomonas albilineans and Xanthomonas sacchari from Tucumán, Argentina, reveals differences in pathogenic strategies

MIELNICHUK, NATALIA; BIANCO, MARÍA I.; YARYURA, PABLO M.; BERTANI, ROMINA P.; TOUM, LAILA; DAGLIO, YASMÍN; COLONNELLA, MARÍA ANTONELA; LIZARRAGA, LEONARDO; CASTAGNARO, ATILIO P.; VOJNOV, ADRIÁN A.

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021

0032-0862

Xanthomonas albilineans (Xa) and X. sacchari (Xs) are both sugarcane pathogens. Xa isthe causal agent of leaf scald disease, but there is limited information about the pathogenicity of Xs. The aim of this work was to study virulence factors of native strains ofXa (Xa32, Xa33, and XaM6) and Xs (Xs14 and Xs15) previously isolated from sugarcanewith leaf scald symptoms, to gain insight into the biology of each microorganism. Weanalysed epiphytic survival, sensitivity to oxidative stress, extracellular degradativeenzymes, cell motilities, exopolysaccharide (EPS) characteristics, cell adhesion, biofilmdevelopment, and control of stomatal regulation of the five strains. We observed thateach species presented similar phenotypes for every factor analysed. Xa strains appeared to be more sensitive to oxidative stress and presented lower epiphytic survivalthan Xs. All strains presented endoglucanase activity; however, we could only detectprotease and amylase activities in Xs strains. Swimming and sliding were higher inXs, but twitching was variable among species. We also observed that only Xs strainsproduced a xanthan-like EPS, presented a strong cell adhesion, and structured biofilm. We detected some intraspecific variations showing that higher amounts of EPSproduced by Xs14 correlated with its higher sliding motility and its homogenous andmore adhesive biofilm. In addition, EPSs of Xs14 and Xs15 presented differences instrand height and acetyl percentage. Finally, we found that strains of both specieswere able to interfere with stomatal aperture mechanism. All these differences couldinfluence the colonization strategies and/or disease progression in each species.