A new allele at the Rps3 locus for resistance to Phytophthora megasperma f. sp. glycinea in soybean

PLOPER, L.D.; ATHOW, K.L.; LAVIOLETTE, F.A.

PHYTOPATHOLOGY

AMER PHYTOPATHOLOGICAL SOC

Lugar: St. Paul, Minnesota, USA; Año: 1985 vol. 75 p. 690 - 694

0031-949X

The genetics of resistance to Phytophthora megasperma f. sp.glycinea was studied in soybean (Glycine max) PI 172901, which was resistant to races 1 through 16 of the pathogen. PI 172901 was crossed to Harosoy (rps), Mukden (Rps1), Sanga (Rps1b), Wells II (Rps1c), Williams 82 (Rps1k), PI 86972-1 (Rps3), PRX27-108 (Rps1 Rps4), and Altonna (Rps6). The F2 populations and the progenies of F2 plants from each cross were evaluated for their reaction to physiologic races 1, 2, 3, 4, 5, 7, and 9 of the fungus. The results showed that there were two independent, dominant genes for resistance in PI 172901. One was Rps1b wich gives resistance to races 1, 3, 4, 5, 7, and 9 and susceptibility to race 2. The other gene was and undescribed allele at the Rps3 locus which confers resistance to the seven physiologic races included in the study. The symbol Rps3b was proposed for this gene to indicate a second allele at the Rps3 locus and to discriminate it from the gene Rps3 which conditions susceptibility to race 7.