Journal of Plant Pathology Archive

Rice panicles with symptoms of bacterial grain rot, i.e. grain abortion, discoloration of the hull and grain, were observed and collected in rice-growing fields of Suncheon-si (Republic of Korea) in September 2015. The lemma and the palea were disassembled from the discolored grains, the insides were rubbed and streaked onto King’s medium B agar plates to ob- tain single colonies (Noh et al., 2012). A PCR-based screening for Burkholderia plantarii was conducted for 66 isolates (Maeda et al., 2006), and two isolates, GRBB 15061 (KACC 18964) and GRBB 15061-1 (KACC 18965) were selected. To confirm the identity of B. plantarii, 16S rRNA gene and two phylogenetic marker genes, rpoD and gyrB, were sequenced and subjected to a BLASTn analysis (Maeda et al., 2006; Yamamoto et al., 2000). The BLASTn results for the 16S rRNA gene sequences of the isolates GRBB 15061 and GRBB 15061-1 (GenBank accession Nos. KX638437 and KX638434, respectively) showed 100% homology with B. plantarii type strain (AB682220.1). The rpoD and gyrB gene sequences of the isolates GRBB 15061 and GRBB 15061-1 (KX638443 and KX638441 for rpoD; KX638428 and KX638431 for gyrB, respectively) showed 99.8% homology (AB190755.1) and 100% homology (AB190645.1) with B. planta- rii type strain. For pathogenicity tests, each isolate of B. plantarii was inoculated into the stem by syringe at the tillering stage and onto the panicle by spraying at the heading stage separately; the inoculated rice stem developed sheath rot and the inoculated panicle developed grain rot. B. plantarii was re-isolated from the symptoms and re-identified, thus satisfying Koch’s postulates. To our knowledge, this is the first report of the bacterial grain rot of rice caused by B. plantarii in the Republic of Korea.