Comparative genomic and phenotypic análisis of three Xanthomonas vesicatoria strains with different degrees of aggressiveness on tomato

JERSON GARITA-CAMBRONERO; GERMÁN DUNGER; ANA MARÍA ROMERO; MARIA ISABEL BIANCO; VALERIA CONFORTE; ADRIÁN VOJNOV; MARIA AGUSTINA PONSO; JAIME CUBERO; GUSTAVO MORALES; PABLO YARYURA

Los Cocos

Congreso; XVII Congreso Argentino de Microbiología General; 2022

SAMIGE

Xanthomonas vesicatoria (Xv) is a member of a complex of species that causes bacterial spot ontomato (Solanum lycopersicum), a disease that affects different plant crops worldwide causing fruitquality decrease and also loss of entire crop production. Bacterial spot is generally controlled usingcopper-based agrochemicals, which contaminate the environment and have led to the emergence ofcopper-resistant Xanthomonas spp. strains. Therefore, to develop sustainable alternative controlstrategies for bacterial spot, it is essential to understand the pathogenic mechanisms used by thesebacteria to infect their hosts. In Argentina, bacterial spot is found in all tomato-producing areas,being Xv one of the main species detected in the fields. Currently, little is known about severalvirulence factors of Xv. Previously, we isolated three native strains of Xv (BNM208, BNM214 andBNM216) from diseased tomato plants, which showed different aggressiveness degrees on tomatoplants. We observed that the most aggressive strain, BNM208, formed a homogeneous, compact andwell-structured biofilm and produced a significantly more viscous xanthan compared with thebiofilms formed by BNM214 and BNM216. Therefore, to elucidate the causes of these differences,we sequenced genomes of the three strains, compared them with each other and with 12 other Xvgenomes, and analyzed groups of genes encoding virulence factors in other phytopathogenicXanthomonas spp., focusing our studies on xanthan and T4P. We did not find differences among thethree strains in the gene cluster encoding xanthan production; however, the microscopicallyobservations of the respective xanthans showed that BNM208 produced larger molecules thanBNM214 and BNM216. This could be related to the higher expression of GumC (protein involved inxanthan polymerization) in BNM208 than in BNM214 and BNM216. Moreover, the three strainsmoved by twitching, a movement depending on T4P, and contain in their genomes Xac3805-like gene(encoding for major pilin in Xanthomonas campestris). Interestingly, only BNM208 contains aXac3241-like gene (encoding for major pilin in Xanthomonas citri). The main pilin(s) of the T4P of Xvis not known at this time: therefore, we suggest that probably the Xac3805-like gene could encodethe major pilin in Xv, but to confirm this, further studies are required