Anastomosis groups of Rhizoctonia solani associated with soybean root and hypocotyl rot in Ontario and resistance of accession PI 442031 to different anastomosis groups

Abstract

Rhizoctonia solani is a complex species and causes soybean root and hypocotyl rot worldwide. Identifying anastomosis groups (AGs) prevalent in a region and growing cultivars with resistance specific to those AGs is a potential means to minimize economic losses from this disease. The main objectives of this study were (i) to identify the predominant AGs of R. solani associated with soybean root and hypocotyl rot in Ontario using both anastomosis grouping and polymerase chain reaction with AG-specific primers; and (ii) to determine the resistance of the soybean accession PI 442031 to different AGs. In 2 years, 278 R. solani isolates were recovered from diseased soybean plants across Ontario and classified into AG-2-2 IIIB (86.0%), AG-4 (1.4%), and AG-5 (12.6%). In general, isolates of AG-2- 2 IIIB were more aggressive than isolates of AG-4 and AG-5. PI 442031 was moderately resistant to all isolates of AG-4 and AG-5, but was highly susceptible to most AG-2-2 IIIB isolates

Keywords:

• disease resistance
• Glycine max
• internal transcribed spacer sequences