Genetic dissection of resistance to anthracnose and powdery mildew in Medicago truncatula.
Medicago truncatula was used to characterize resistance to anthracnose and powdery mildew caused by Colletotrichum trifolii and Erysiphe pisi, respectively. Two isolates of E. pisi (Ep-p from pea and Ep-a from alfalfa) and two races of C. trifolii (races 1 and 2) were used in this study. The A17 genotype was resistant and displayed a hypersensitive response after inoculation with either pathogen, while lines F83005.5 and DZA315.16 were susceptible to anthracnose and powdery mildew, respectively. To identify the genetic determinants underlying resistance in A17, two F7 recombinant inbred line (RIL) populations, LR4 (A17 x DZA315.16) and LR5 (A17 x F83005.5), were phenotyped with E. pisi isolates and C. trifolii races, respectively. Genetic analyses showed that i) resistance to anthracnose is governed mainly by a single major locus to both races, named Ct1 and located on the upper part of chromosome 4; and ii) resistance to powdery mildew involves three distinct loci, Epp1 on chromosome 4 and Epa1 and Epa2 on chromosome 5. The use of a consensus genetic map for the two RIL populations revealed that Ct1 and Epp1, although located in the same genome region, were clearly distinct. In silico analysis in this region identified the presence of several clusters of nucleotide binding site leucine-rich repeat genes. Many of these genes have atypical resistance gene analog structures and display differential expression patterns in distinct stress-related cDNA libraries.
UMR 5546, Centre National de la Recherche Scientifique-UPS, Pôle de Biotechnologie Végétale, 24 Chemin Borde Rouge, 34326 Castanet-Tolosan, France.
Carine
C
Ameline-Torregrosa
Marc
M
Cazaux
Dariush
D
Danesh
Fabien
F
Chardon
Steven B
SB
Cannon
Marie-Thérèse
MT
Esquerré-Tugayé
Bernard
B
Dumas
Nevin D
ND
Young
Deborah A
DA
Samac
Thierry
T
Huguet
Christophe
C
Jacquet
D001203:Ascomycota / Q000502:physiology*; D032461:Chromosomes, Plant; D020231:Colletotrichum / Q000502:physiology*; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D005819:Genetic Markers; D005838:Genotype; D007113:Immunity, Innate / Q000235:genetics* / Q000276:immunology; D007178:Inbreeding; D046913:Medicago truncatula / Q000235:genetics* / Q000276:immunology / Q000382:microbiology* / Q000648:ultrastructure; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology / Q000648:ultrastructure; D040641:Quantitative Trait Loci
D005819:Genetic Markers