Soybean resistance genes specific for different Pseudomonas syringae avirulence genes are allelic, or closely linked, at the RPG1 locus.

RPG1 and RPM1 are disease resistance genes in soybean and Arabidopsis, respectively, that confer resistance to Pseudomonas syringae strains expressing the avirulence gene avrB. RPM1 has recently been demonstrated to have a second specificity, also conferring resistance to P. syringae strains expressing avrRpm1. Here we show that alleles, or closely linked genes, exist at the RPG1 locus in soybean that are specific for either avrB or avrRpm1 and thus can distinguish between these two avirulence genes.