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

MIELNICHUK, NATALIA; BIANCO, MARÍA ISABEL; YARYURA, PABLO MARCELO; BERTANI, ROMINA PRISCILA; TOUM, LAILA; DAGLIO, YASMÍN; COLONNELLA, MARÍA ANTONELA; LIZARRAGA, LEONARDO; CASTAGNARO, ATILIO PEDRO; VOJNOV, ADRIÁN ALBERTO

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021

0032-0862

Xanthomonas albilineans (Xa) and X. sacchari (Xs) are both sugarcane pathogens. Xa is thecausal agent of leaf scald disease, but there is limited information about the pathogenicity ofXs. The aim of this work was to study virulence factors of native strains of Xa (Xa32, Xa33,and XaM6) and Xs (Xs14 and Xs15) previously isolated from sugarcane with leaf scaldsymptoms, to gain insight into the biology of each microorganism. We analysed epiphyticsurvival, sensitivity to oxidative stress, extracellular degradative enzymes, cell motilities,exopolysaccharide (EPS) characteristics, cell adhesion, biofilm development, and control ofstomatal regulation of the five strains. We observed that each species presented similarphenotypes for every factor analysed. Xa strains appeared to be more sensitive to oxidativestress and presented lower epiphytic survival than Xs. All strains presented endoglucanaseactivity; however, we could only detect protease and amylase activities in Xs strains.Swimming and sliding were higher in Xs, but twitching was variable among species. We alsoobserved that only Xs strains produced a xanthan-like EPS, presented a strong cell adhesion,and structured biofilm. We detected some intraspecific variations showing that higheramounts of EPS produced by Xs14 correlated with its higher sliding motility and itshomogenous and more adhesive biofilm. In addition, EPSs of Xs14 and Xs15 presenteddifferences in strand height and acetyl percentage. Finally, we found that strains of bothspecies were able to interfere with stomatal aperture mechanism. All these differences couldinfluence the colonization strategies and/or disease progression in each species.