Soybean stem canker is a serious soybean (Glycine max) disease caused by the fungi Diaporthe phaseolorum f. sp. meridionalis/Phomopsis phaseoli f. sp. meridionalis. We have crossed the soybean resistant line UFV 91-61 with the susceptible cultivar Paranaiba, and analyze the F2 population in order to understand the genetics underlying resistance to this pathogen (isolate CH8) and to identify molecular markers linked to it. The results indicate that a single dominant gene controls resistance to this isolate. RAPD analysis in the F2 population identified two DNA fragments of approximately 1,150 and 1,320 bp of primer OPAB19 linked in the repulsion and coupling phase at 4.7 cM of the resistance gene of line UFV 91-61. These markers will be very useful for monitoring the introgression of this gene into soybean adapted cultivars, and open up the possibility for a systematic search for markers linked to other resistance genes for stem canker that could be pyramided into the same genetic background.
