Polyphasic identification of Pseudomonas fuscovaginae causing sheath and glume lesions on rice in Australia

Pathogenic fluorescent pseudomonads associated with sheath brown rot disease symptoms on near-mature rice were characterised by a polyphasic study. Twelve strains of Pseudomonas fuscovaginae from the International Collection of Microorganisms from Plants (ICMP), which represent those strains lodged in several world culture collections, were used for comparison. Two strains, ICMP 9997 and 9999, were considered to have no similarity at all to P. fuscovaginae and a further two strains, ICMP11283 and 11284, were considered, by fatty acid analysis, to be more closely related to P. putida. These two strains were related to P. marginalis according to Biolog, and to P. tolaasii according to 16s and rpoB data. The Australian rice isolates were all identified as P. putida Biotype A by fatty acid analysis or as P. asplenii (4 isolates), P. fuscovaginae (2 isolates) or P. fluorescens (1 isolate) by Biolog. Sequencing of the 16s rRNA gene placed the rice isolates with P. fuscovaginae and P. asplenii, whereas rpoB gene sequence analysis showed a higher similarity to P. fuscovaginae than to P. asplenii. This is the first report of P. fuscovaginae in Australia.