ORIGIN OF SOYBEAN ALLELES FOR PHYTOPHTHORA RESISTANCE IN CHINA

Since Phytophthora sojae Kauf. & Gerde. is constantly evolving new rac es that overcome the resistance genes that have been deployed in soybe an cultivars [Glycine max (L.) Merr.], the search for new sources of r esistance is important in breeding programs involving disease manageme nt strategies. No systematic screening of the germplasm collection has been made that would give us an indication of the prevalence and dist ribution of phytophthora resistance in China. The objective of this st udy was to examine the distribution of Phytophthora resistant soybean in central China. By means of hypocotyl inoculation in the greenhouse, lines from central China were classified for their reaction to Races 1, 3, 7, and 25 of P. sojae in 1993 and 1991 at Urbana, IL, and Wooste r, OH. Resistance was more frequent in the eastern provinces with the origin of Rps1-d in central China. Any searches for new P. sojae resis tance genes in soybean should be focused on the Chinese provinces (Anh ui and Jiangsu) with the highest incidence of resistant soybean lines.