Xylose Isomerase Depletion Enhances Virulence of Xanthomonas citri subsp. citri in Citrus aurantifolia

Citrus canker, caused by the bacterium Xanthomonas citri (Xcc), is one of most devastating diseases for citrus industry. Xylose a constituent cell wall plants, and ability Xcc to use this carbohydrate may play role in virulence. has two genes codifying xylose isomerase (XI), bifunctional enzyme that interconverts D-xylose into D-xylulose D-glucose D-fructose. The aim work was investigate functional putative XI ORFs, XAC1776 (xylA1) XAC4225 (xylA2), pathogenicity. XI-coding were deleted, single mutants (XccΔxylA1 or XccΔxylA2) double mutant (XccΔxylA1ΔxylA2) remained viable. deletion both (xylA1 and/or xylA2) increased aggressiveness mutants, causing disease symptoms. RT-qPCR analysis wild strain xylA grown vivo vitro revealed highest expression level hrpX xylR observed mutant. results indicate depletion increases hrp regulatory Xcc. We concluded intracellular accumulation enhances