Pcr primers for detection of plant pathogenic species and subspecies of

Abstract

We sequenced a 625 and 617 bp fragment of the inner spacer region of 16S-23S rDNA of a strain of Acidovorax avenae representing pathogens from several hosts, including foxtail, oats, corn, rice, millet, sugarcane, orchid, and watermelon and a strain of A. avenae subsp. citrulli pathogenic only to watermelon, respectively, for the purpose of designing PCR primers for their identification. These plant pathogens were previously considered as non-fluorescent pseudomonads and have been recently reclassified as Acidovorax avenae subsp. avenae, A. avenae subsp. cattleyae, and A. avenae subsp. citrulli. Several sets of primers were designed. Primers identified by SEQ ID NO:1 and SEQ ID NO:2 of subsp. avenae reacted with all strains of A. avenae subsp. avenae (previously named P. avenae or P. alboprecipitans) originating from foxtail, oats, corn, rice, sugarcane, and millet, A. avenae subsp. cattleyae from orchid, and A. avenae subsp. citrulli (previously named P. pseudoalcaligenes subsp. citrulli) from watermelon. Primers identified by SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6 of subsp. citrulli reacted with all strains of A. avenae subsp. citrulli, but not with any other strain of subsp. avenae. None of fifty-three other bacteria tested reacted with either set of primers. The citrulli- specific primers should prove especially useful for specific, sensitive, and rapid detection of this serious seedborne pathogen of watermelon seeds.