Bacterial Diseases of Rice. II. Characterization of Pathogenic Bacteria Associated with Sheath Rot Complex and Grain Discoloration of Rice in the Philippines. B. Cottyn, Project Scientist, Entomology and Plant Pathology Division, International Rice Research Institute, Box 933, Manila, Philippines. M. F. Van Outryve, Project Scientist, Laboratorium voor Microbiologie, Universiteit Gent, K. Ledeganckstraat 35, 9000 Gent, Belgium; M. T. Cerez, Research Assistant, Entomology and Plant Pathology Division, International Rice Research Institute, Box 933, Manila, Philippines; M. De Cleene, Professor, and J. Swings, Professor, Laboratorium voor Microbiologie, Universiteit Gent, K. Ledeganckstraat 35, 9000 Gent Belgium; and T. W. Mew, Plant Pathologist and Head, Entomology and Plant Pathology Division, International Rice Research Institute, Box 933, Manila, Philippines. Plant Dis. 80:438. Accepted for publication 13 November 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0438.

From over 5,600 bacteria isolated from rice plants with sheath rot complex and grain discoloration syndrome, and two batches of I kg of rice seed (cultivars IR54 and IR8866), 204 pathogens were initially characterized by Phenotypic tests, serology, and growth on selective media, and further distinguished by API 20NE, Biolog, and cellular fatty acid methyl ester-fingerprints. The best differentiation was obtained by the Biolog system. The nonfluorescent pathogens were represented by clusters Dl {Burkholderia glumae, formerly Pseudomonas glumae) and E {Acidovorax avenae subsp, avenae, formerly Pseudomonas avenae). Seven clusters were distinguished among the fluorescent strains associated with sheath rot complex and grain discoloration. Cluster A5 was identified as Pseudomonas aeruginosa, and cluster Bl as P. fuscovaginae. Cluster B2 is related to Pseudomonas aureofaciens, P. corrugala, P. fluorescens, and P. marginalis. Clusters Bl and B2 were only slightly different. The strains identified as P. fuscovaginae were different from the type strains in 2-ketogluconate production.