High Quality Content by WIKIPEDIA articles! Xanthomonas oryzae is a species of proteobacteria. The major host of the bacteria is rice. The species contains two pathovars which are non-European: Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. Oryzicola. Host resistance gene, Xa21,from Oryza longistaminata is integrated into the genome of Oryza sativa for the board range resistance of rice blight disease caused by Xanthomonas oryzae pv. Oryzae. The Proteobacteria are a major group (phylum) of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, and many other notable genera.