D-amino acids exist in many bacteria, fungi and insects, but little investigation into their function has been performed. In this study, we determined the antibacterial effect of D-Leu on Xanthomonas citri subsp. citri (Xcc), a plant pathogen that is extremely detrimental to the production of Citrus fruit. Our results showed that 2 mM D-Leu morphologically altered Xcc strain 101 from rod to chain form and 7 mM D-Leu caused Xcc strain 101 to lose pathogenicity and/or die. Electro-microscopic examination revealed that the bacterial chain was formed by many bacteria own some cell membrane, and the cellular membrane broken and protoplasm prolapse out. This discovery has the potential to provide a new preventative strategy against bacterial diseases of plants and to screen for biocontrol bacteria.
D-amino acids; plant pathogenic bacteria; morphological change; killing effect;Xanthomonas citri subsp. citri
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