Bacterial Diseases of Rice. II. Characterization of Pathogenic Bacteria Associated with Sheath Rot Complex and Grain Discoloration of Rice in the Philippines

Abstract

From over 5,600 bacteria isolated from rice plants with sheath rot complex and grain discoloration syndrome, and two batches of 1 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 esterfingerprints. The best differentiation was obtained by the Biolog system. The nonfluorescent pathogens were represented by clusters D1 (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 B1 as P. fuscovaginae. Cluster B2 is related to Pseudomonas aureofaciens, P. corrugata, P. fluorescens, and P. marginalis. Clusters B1 and B2 were only slightly different. The strains identified as P. fuscovaginae were different from the type strains in 2-ketogluconate production.