Inheritance of a Second Major Gene for Resistance to Phytophthora Rot in Soybeans¹

Abstract

The inheritance of another gene for resistance to Phytophthora megasperma Drechs. var. sojae Hildeb. in soybeans [ Glycine max (L.) Merr.] was studied. This dominant gene, proposed as Rps 2 , is found in the cultivars ‘CNS’ and derived strains. The results obtained indicated that Rps 2 is at a locus different from the Rps , rps 2 , rps locus. It is suggested that the first locus should now be changed from Rps , rps 2 , rps to Rps 1 , rps 1 2 , rps 1 to distinguish it from the second locus, Rps 2 rps 2 , Rps 2 has given a high level of resistance to phytophthora rot in repeated field plantings under conditions favorable for development of the disease. Screening for Rps 2 is easily accomplished by growing plants in a liquid culture medium with the pathogen.