BACTERIAL DISEASES OF RICE .2. CHARACTERIZATION OF PATHOGENIC BACTERIA ASSOCIATED WITH SHEATH ROT COMPLEX AND GRAIN DISCOLORATION OF RICE IN THE PHILIPPINES

From over 5,600 bacteria isolated from rice plants with sheath rot com plex and grain discoloration syndrome, and two batches of 1 kg of rice seed (cultivars IR54 and 1R8866), 204 pathogens were initially charac terized 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 t he Biolog system. The nonfluorescent pathogens were represented by clu sters D1 (Burkholderia glumae, formerly Pseudomonas glumae) and E (Aci dovorax avenae subsp. avenae, formerly Pseudomonas avenae). Seven clus ters were distinguished among the fluorescent strains associated with sheath rot complex and grain discoloration. Cluster A5 was identified as Pseudomonas aeruginosa, and cluster B1 as P. fuscovaginae. Cluster B2 is related to Pseudomonas aureofaciens, P. corrugata, FI fluorescen s, and P. marginalis. Clusters B1 and B2 were only slightly different. The strains identified as P. fuscovaginae were different from the typ e strains in 2-ketogluconate production.