Genetic and physical localization of the soybean Rpg1-b disease resistance gene reveals a complex locus containing several tightly linked families of NBS-LRR genes.
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 spanning approximately 270 kilobases. Rpg1-b is part of a complex locus containing numerous genes related to previously characterized coiled coil-nucleotide binding site-leucine rich repeat (CC-NBS-LRR)-type R genes that are spread throughout this region. Phylogenetic and Southern blot analyses group these genes into four distinct subgroups, some of which are conserved in the common bean, Phaseolus vulgaris, indicating that this R gene cluster may predate the divergence of Phaseolus and Glycine. Members from different subgroups are physically intermixed and display a high level of polymorphism between soybean cultivars, suggesting that this region is rearranging at a high frequency. At least five CC-NBS-LRR-type genes cosegregate with Rpg1-b in our large mapping populations.
Ashfield
Tom
T
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Bocian
Anna
A
Held
Dan
D
Henk
Adam D
AD
Marek
Laura Fredrick
LF
Danesh
Dariush
D
Peñuela
Silvia
S
Meksem
Khalid
K
Lightfoot
David A
DA
Young
Nevin D
ND
Shoemaker
Randy C
RC
Innes
Roger W
RW
D000595:Amino Acid Sequence; D001483:Base Sequence; D022202:Chromosomes, Artificial, Bacterial; D017931:DNA Primers; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000235:genetics*
D017931:DNA Primers; D010940:Plant Proteins