Xanthomonas oryzae pv. oryzae PXO99A

The Xanthomonadaceae are a family of Gram negative bacteria belonging to the order Xanthomonadales in the gammaproteobacteria. They are typically characterized as environmental organisms and are found in soil and water, as well as plant tissues. Many Xanthomonadaceae, especially species from the genera Xanthomonas and Xylella, cause plant diseases. Only one, Stenotrophomonas maltophilia, has isolates known to be opportunistic human pathogens.Xanthomonas oryzae is a Gram-negative bacterium and is the causative agent of bacterial blight on rice. Bacterial blight is a major disease in rice producing countries where high-yielding rice cultivars are often highly susceptible to it. It is a vascular disease resulting in tannish-gray to white lesions along the leaf veins. In severely infested fields, bacterial blight can cause yield losses up to 50%. When it infects at the seedling stage, it causes a syndrome known as kresek, which can lead to nearly complete crop loss.PXO99A is a 5-azacytidine-resistant derivative of PXO99, which was isolated in the Philippines. Genotypically PXO99 is more similar to isolates from Nepal and India than to other Philippine isolates. In contrast to other fully-sequenced X.oryzae pv. oryzae strains MAFF and KACC, PXO99A is virulent toward a large number of rice varieties representing diverse genetic sources of resistance. Due to its amenability to genetic analysis, and its relatively broad cultivar specificity, PXO99A has been the focus of numerous studies of the molecular basis of bacterial blight and blight resistance (adapted from PubMed 18452608). (EBI Integr8)