High Frequency of Brown Stem Rot Resistance in Soybean Germ Plasm from Central and Southern China

In an effort to identify new sources of resistance to brown stem rot, caused by Phialophora gregata, 829 soybean accessions originating from 14 provinces in central and southern China and ranging in maturity from group IV to group VIII were obtained from the USDA Soybean Germplasm Collection. All accessions were inoculated in sequential evaluations in the greenhouse with three isolates of P. gregata. Putatively resistant accessions were compared statistically with resistant and susceptible standards. Two hundred forty-one, or approximately 29% of the accessions evaluated, were resistant to all three isolates of P. gregata. The percentage of resistant accessions varied among provinces, with the highest percentages identified in the provinces of Anhui, Gansu, Jiangsu, and Sichuan. Resistance to brown stem rot was not associated with maturity of the accessions or presence of soybean mosaic virus. These resistant accessions could be utilized as sources of brown stem rot resistance through integration of northern and southern soybean germ plasm.