The Mla (powdery mildew) resistance cluster is associated with three NBS-LRR gene families and suppressed recombination within a 240-kb DNA interval on chromosome 5S (1HS) of barley.
Powdery mildew of barley, caused by Erysiphe graminis f. sp. hordei, is a model system for investigating the mechanism of gene-for-gene interaction between large-genome cereals and obligate-fungal pathogens. A large number of loci that confer resistance to this disease are located on the short arm of chromosome 5(1H). The Mla resistance-gene cluster is positioned near the telomeric end of this chromosome arm. AFLP-, RAPD-, and RFLP-derived markers were used to saturate the Mla region in a high-resolution recombinant population segregating for the (Mla6 + Mla14) and (Mla13 + Ml-Ru3) resistance specificities. These tightly linked genetic markers were used to identify and develop a physical contig of YAC and BAC clones spanning the Mla cluster. Three distinct NBS-LRR resistance-gene homologue (RGH) families were revealed via computational analysis of low-pass and BAC-end sequence data derived from Mla-spanning clones. Genetic and physical mapping delimited the Mla-associated, NBS-LRR gene families to a 240-kb interval. Recombination within the RGH families was at least 10-fold less frequent than between markers directly adjacent to the Mla cluster.
Wei
F
F
Interdepartmental Genetics Program, USDA-ARS, Iowa State University, Ames, Iowa 50011-1020, USA.
Gobelman-Werner
K
K
Morroll
S M
SM
Kurth
J
J
Mao
L
L
Wing
R
R
Leister
D
D
Schulze-Lefert
P
P
Wise
R P
RP
D000483:Alleles; D001203:Ascomycota / Q000472:pathogenicity; D001483:Base Sequence; D002875:Chromosomes; D018244:Chromosomes, Artificial, Yeast; D003001:Cloning, Molecular; D017931:DNA Primers; D001467:Hordeum / Q000235:genetics*; D005810:Multigene Family; D010935:Plant Diseases / Q000235:genetics*; D011995:Recombination, Genetic; D018626:Retroelements
D017931:DNA Primers; D018626:Retroelements