Resistance to Colletotrichum lindemuthianum in Phaseolus vulgaris: a case study for mapping two independent genes.
Anthracnose, caused by the hemibiotrophic fungal pathogen Colletotrichum lindemuthianum is a devastating disease of common bean. Resistant cultivars are economical means for defense against this pathogen. In the present study, we mapped resistance specificities against 7 C. lindemuthianum strains of various geographical origins revealing differential reactions on BAT93 and JaloEEP558, two parents of a recombinant inbred lines (RILs) population, of Meso-american and Andean origin, respectively. Six strains revealed the segregation of two independent resistance genes. A specific numerical code calculating the LOD score in the case of two independent segregating genes (i.e. genes with duplicate effects) in a RILs population was developed in order to provide a recombination value (r) between each of the two resistance genes and the tested marker. We mapped two closely linked Andean resistance genes (Co-x, Co-w) at the end of linkage group (LG) B1 and mapped one Meso-american resistance genes (Co-u) at the end of LG B2. We also confirmed the complexity of the previously identified B4 resistance gene cluster, because four of the seven tested strains revealed a resistance specificity near Co-y from JaloEEP558 and two strains identified a resistance specificity near Co-9 from BAT93. Resistance genes found within the same cluster confer resistance to different strains of a single pathogen such as the two anthracnose specificities Co-x and Co-w clustered at the end of LG B1. Clustering of resistance specificities to multiple pathogens such as fungi (Co-u) and viruses (I) was also observed at the end of LG B2.
Geffroy
Valérie
V
Institut de Biotechnologie des Plantes (IBP), INRA, Université Paris-Sud, UMR-CNRS 8618, bât. 630, 91405, Orsay Cedex, France. valerie.geffroy@u-psud.fr
Sévignac
Mireille
M
Billant
Paul
P
Dron
Michel
M
Langin
Thierry
T
D002874:Chromosome Mapping; D020231:Colletotrichum / Q000502:physiology*; D017343:Genes, Plant; D005838:Genotype; D007113:Immunity, Innate / Q000235:genetics* / Q000276:immunology; D007178:Inbreeding; D016013:Likelihood Functions; D008126:Lod Score; D027805:Phaseolus / Q000235:genetics* / Q000382:microbiology*; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*