Phytophthora root rot, caused by Phytophthora sojae (Kaufmann and Gerdeman) is a destructive disease of soybean (Glycine max) worldwide. The disease can cause seedling, root and stem rot with severe reduction in the yield. Thirteen resistance genes (Rps), at seven loci, that confer immunity or partial resistance to one or more race of P. sojae have been characterized. Two types of resistance to P. sojae have been characterized, immunity or race specific resistance conferred by 12 of the described genes, and field resistance (syn., tolerance) conferred by the Rps 2 gene. Fifty-three physiological races of P. sojae have been identified on differential soybean genotypes since the disease was first reported in 1955. Race 1 had been reported in China. As pathogens evolved simultaneously with their hosts, there could be rich type of the Phytophthora physiological races in China. During 1998-1999, We collected and identified 18 isolates of P. sojae from 5 counties (or cities) in Heilongjiang Province. This paper reported the identification of the physiological races.
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