Submitted to: Molecular Plant Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2003
Publication Date: 9/13/2003
Citation: Ashfield, T., Bocian, A., Held, D., Henk, A.D., Marek, L.F., Danesh, D., Lightfoot, D.A., Penuela, S., Meksem, K., Shoemaker, R.C. 2003. Genetic and physical mapping of the soybean rpg1-b disease resistance gene reveals a complex locus containing several tightly linked families of nbs-lrr-genes. Molecular Plant Microbe Interactions. v. 16. p. 817-826. Interpretive Summary: Bacterial diseases result in the loss of an average of 2 million bushels of soybean each year in the north central states. Bacterial blight is a major bacterial disease. Understanding how resistance genes function is an important step toward controlling diseases. In this research the authors isolated and analyzed the hereditary material containing a cluster of disease resistance genes. They found that several resistance gene look-alikes were tightly clustered in the same region and that the genes resembled other well-studied resistance genes. These findings strengthen the belief that disease resistance to many types of pests and pathogens occurs by similar mechanisms. This information will be of value to scientists who are attempting to determine how better resistance can be engineered into important crop plants.
Technical Abstract: Alleles, or tightly linked genes, at the soybean (Glycine max L. Merr.) Rpg1 locus confer resistance to strains of Pseudomonas syringae pv. glycinea that express the avirulence genes avrB or avrRpm1. We have previously mapped Rpg1-b (the gene specific for avrB) to a cluster of resistance genes (R-genes) with diverse specificities in molecular linkage group F. Here we describe the high-resolution physical and genetic mapping of Rpg1-b to a 0.16 cM interval encompassed by two overlapping BAC clones. Rpg1-b is part of a complex locus containing numerous genes related to previously characterized CC-NBS-LRR-type R-genes which are spread over several hundred kilobases. At least five CC-NBS-LRR type genes co-segregate with Rpg1-b in our large mapping populations. The possible implications for the evolutionary relationship between Rpg1-b and RPM1, a functionally analogous R-gene from Arabidopsis, are discussed.