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Genetic and physical mapping of the SH3 region that confers resistance to leaf rust in coffee tree (Coffea arabica L.)

Lashermes P., Combes M.C., Ribas A., Cenci A., Mahé L., Etienne H.. 2010. Tree Genetics and Genomes, 6 (6) : p. 973-980.

Resistance to coffee leaf rust is conferred by SH3, a major dominant gene that has been introgressed from a wild coffee species Coffea liberica (genome L) into the allotetraploid cultivated species, Coffea arabica (genome CaEa). As the first step toward the map-based cloning of the SH3 gene, using a bacterial artificial chromosome (BAC) library, we describe the construction of a physical map in C. arabica spanning the resistance locus. This physical map consists in two homeologous BAC-contigs of 1,170 and 1,208 kb corresponding to the subgenomes Ca and Ea, respectively. Genetic analysis was performed using a single nucleotide polymorphism detection assay based on Sanger sequencing of amplicons. The C. liberica-derived chromosome segment that carries the SH3 resistance gene appeared to be introgressed on the sub-genome Ca. The position of the SH3 locus was delimited within an interval of 550 kb on the physical map. In addition, our results indicated a sixfold reduction in recombination frequency in the introgressed SH3 region compared to the orthologous region in Coffea canephora. (Résumé d'auteur)

Mots-clés : rouille; hemileia vastatrix; génétique des populations; introgression; polyploïdie; clonage de gène; recombinaison; résistance génétique; résistance aux maladies; carte génétique; coffea canephora; coffea arabica; france

Thématique : Génétique et amélioration des plantes; Maladies des plantes

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