A 3.1-kb genomic fragment of Bacillus subtilis encodes the protein inhibiting growth of Xanthomonas oryzae pv. oryzae

AIMS: To clone genes of Bacillus subtilis encoding peptides that inhibit the growth of Xanthomonas orzae pv. oryzae (Xoo). METHODS AND RESULTS: A 3.1-kb DNA fragment from B. subtilis SO113 encoding peptides that inhibit the growth of Xoo (anti-Xoo, showing an inhibition zone) was isolated from a plasmid library of B. subtilis 6 GM15. Sequence analysis revealed that it contained three complete open reading frames (ORFs): ybcO, ybcS and a novel ORF designated ybcPQ. Deleting the last 96 bp of ybcS from the plasmid eliminated the anti-Xoo activity, suggesting that ybcS is required for producing the anti-Xoo activity. However, no anti-Xoo activity could be detected for the plasmid with ybcS alone. Further analysis showed that ybcO, at least, was also required to obtain the anti-Xoo activity. CONCLUSIONS: A fragment of B. subtilis has been cloned that expresses an anti-Xoo activity that requires ybcS and ybcO. SIGNIFICANCE AND IMPACT OF THE STUDY: These genes could be useful for the genetic engineering of resistance to rice bacterial diseases and for the design of new anti-Xoo biocontrol agents.