Characterization of Xanthomonas isolates causal of citrus canker type A in Tucumán, Argentina, and biocontrol strategies using olive and wine-derived agro-industrial wastes.

Abstract

Abstract Argentina ranks fourth as a lemon producer worldwide and first in lemon industrialization. At the same time, Tucumán (NW region of Argentina) is the leading national producer and exporter of lemons and the fourth largest exporter of fresh lemons worldwide. Citrus canker is one of the major diseases that threaten citrus production, and its causal agent, Xanthomonas citri subsp. citri is present in all citrus-growing areas worldwide, including Tucumán. Due to the current global awareness of environmental care and the demand for organic food, the present study aims to characterize Xanthomonas strains in Tucumán and further evaluate the potential of wine-derived agro-industrial wastes as a natural alternative to control citrus canker. In this vein, we focused on those by-products derived from the olive (‘Alperujo’) and wine (‘Orujo’) industries. The current study provides an updated characterization of the Xanthomonas species isolated in Tucumán and confirms that all the isolates pertained to citrus canker type A. Such strains were clustered into four groups according to their distinctive features: in vitro growth, biofilm formation, metabolic activity, exopolysaccharide content, swarming mobility, and pathogenicity. We further demonstrated that ‘Alperujo’ extracts mainly inhibited bacterial growth, while ‘Orujo’ extracts were most active against biofilm production and bacterial motility, with evident antibacterial activity. Overall, this study confirms the presence of pathotype A of X. citri subsp. citri strains in Tucumán, Argentina, and proposes to use olive and wine agro-industrial sub-products as an efficient bio-input to control the causal agent of citrus canker in lemons.