Vitamin B6 biosynthesis is essential for the virulence of Xanthomonas oryzae pv. oryzae

Abstract

AbstractXanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease, which threatens rice production around the world. Efficient infection of rice leaves by Xoo depends on its ability to obtain nutrients from the plant and to cope with the host defence responses. Vitamin B6 (VB6) is essential to the growth of all organisms, but bacteria and plants use different biosynthesis pathways, meaning VB6 biosynthesis might be attractive as an antibacterial target. In bacteria, deoxyxylose 5‐phosphate (DXP)‐dependent and deoxyxylose 5‐phosphate‐independent biosynthesis pathways can produce VB6. However, the Xoo VB6 biosynthesis pathway has not been experimentally identified, and its role in Xoo virulence remains unclear. Here, we analysed the VB6 biosynthesis pathway in Xoo and its role in host–pathogen interactions. PdxA and PdxJ are key components for DXP‐dependent VB6 biosynthesis; we found that Xoo mutants containing mutations in these two putative genes (pdxA and pdxJ) were fully auxotrophic for VB6, demonstrating that Xoo VB6 de novo biosynthesis is DXP‐dependent. We also found that mutation of these key genes (pdxA and pdxJ) significantly reduced Xoo virulence in rice. These results suggest that VB6 de novo biosynthesis is essential for Xoo virulence.