PAG-IV Plant Genome IV Conference

Town & Country Conference Center, San Diego, CA, January, 1995.

W24
Anthracnose Resistance in Phaseolus vulgaris: How Many Genes and What is the Molecular Basis for Resistance?

V. GEFFROY(1,2), F. Creusot(1), M. Sevignac(1), C. Riou(1), J. Falquet(1), J.V. Fabre(1), D. Sicard(1), C. Neema(1), A.F. Adam-Blondon(1,3) and M. Dron(1)
1. Laboratoire de Phytopathologie Moleculaire, IBP, Universite Paris XI, URA 1128, 91405 Orsay, France
2. INRA, Domaine de Brunehaut, Estrees-Mons, 80200 Peronne, France
3. INRA, Recherches viticoles, Domaine du Chapitre, 170, rue du chapitre, 34750 Villeneuve-Les-Maguelonne, France

Anthracnose, caused by Colletotrichum lindemuthianum, is a severe disease of common bean in tropical areas. Botany studies had shown that bean diversity originated from 3 different gene pools (Meso-america; Ecuador; NorthEast Argentina). Genetic studies have discriminated 8 different, dominant resistance genes (Co1 to Co8). Seven of these genes are from the Meso-american gene pool. In the present work, strains of Colletotrichum lindemuthianum have been collected on beans from either the Mesoamerican or the Andean gene pools. A population genetic analysis has identified a strong differentiation among the strains from these 2 gene pools. The BAT93 (Meso-american) x JaloEEP558 (Andean) RILs have been used to extend the basis of the genetic determinism of anthracnose resistance in the 2 gene pools. Andean Colletotrichum lindemuthianum strains only attack the andean parent JaloEEP558; the opposite status appears to be observed for Bat93 with few exceptions. A preliminary genetic analysis has revealed four additional genes in this RILs population. One of the resistance gene (Co2/ ARE) has been investigated in more details. A RAPD marker (RoH20) was previously shown to present a strong linkage with the Co2 locus. Genetic and molecular studies have established that RoH20 corresponds to a repeated sequence which cosegregates with the Co2 locus. The sequence of one of these copies has revealed a single ORF encoding a protein possessing 23 LeucineRichRepeats related to RPS2 resistance gene isolated Arabidopsis. Complementation studies and molecular analysis of the Co2 locus are underway to know whether one of these sequences corresponds to the Co2 resistance gene.

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