Résumé
In several plant species, the DREB genes play a key role in responses to abiotic stress. Since the development of molecular markers is one of the major goals for accelerating breeding programs, a study was done to evaluate the sequence variability of the DREB1D gene in several Coffea genotypes. The promoter and coding regions of this gene were cloned and sequenced from 16 coffee plants (including 10 from C. arabica and 4 from C. canephora), most of them characterized by different phenotypes (tolerance vs. susceptibility) regarding to drought. This showed that the DREB1D-coding sequence was highly conserved within coffee plants. However, several nucleic polymorphisms ("single nucleotide polymorphism" [SNP] and insertion/deletion [INDELs]) were found in the coffee DREB1D promoter regions. These polymorphisms could explained the differences of DREB1D gene expression levels previously observed in leaves of drought tolerant and susceptible clones of C. canephora. These polymorphisms also allowed the identification of different haplotypes like orthologous sequence variants (OSVs) of C. canephora and C. eugenioides as well as homologous single-nucleotide variants (HSVs) for C. arabica subgenomes (C. canephora and C. eugenioides) that could be used to develop allele and homoeologous specific markers for this locus. Work is now under way to evaluate the capacity of DREB1D promoter regions to control the expression of the uidA reporter gene in transgenic coffee plants. Work supported by CAPES-COFECUB, Consórcio Pesquisa Café and INCT-Café (CNPq/FAPEMIG). (Texte intégral)