English
Fungal phytopathogens including Rhizoctonia sp. causes severe root rot and damping off leads to yield and plant health loss in soybean. In August 2023, two Rhizoctonia strains were isolated from diseased soybeans during disease monitoring in soybean fields in Gimje. Molecular phylogeny analysis identified the strains as Rhizoctonia bicornis strains, and following pathogenicity revealed significantly higher virulence of Rhizoctonia bicornis AG-O CMML23-1 compared to R. bicornis AG-Fa CMML23-2. The R. bicornis CMML23-1 caused severe rot and approximately 90% of germination inhibition rate of tested soybean seeds. To investigate potential for chemical control of pathogen, benomyl, pyraclostrobin, pydiflumetofen, and hexaconazole were tested against the R. bicornis CMML23-1. Among the tested fungicides, pyraclostrobin showed the highest control efficacy value and average plant fresh weight in pot assay against R. bicornis CMML23-1. The qRT-PCR assay using TaqMan® for detection of Rhizoctonia isolates was performed and detected the isolates in soil samples from fields or paddy fields in Nonsan, Buan, and Gimje. To investigate pathogenicity factors in the fungal pathogen, , the genome of R. bicornis CMML23-1 was sequenced using Illumina NovaSeq and PacBio HiFi sequencing. Assembled draft genome sequence was a total of 61.5 Mbp long, and assessed BUSCO completeness was 90.8%, indicating successful assembly of the genome. Further orthoMCL analysis of secretomes of CMML23-1 and other Rhizoctonia solani strains revealed unique protein cluster composed of beta/gamma crystallin proteins in CMML23-1. Altogether, this study will provide comprehensive understanding of pathogenicity and genomics in Rhizoctonia sp.
