Résumé
Iron (Fe) is one of the most important elements in plant mineral nutrition. Fe deficiency is critical abiotic stress factor for Mediterranean citriculture and the development of marker assisted selection (MAS) for this trait would be a great aid for rootstock breeding. In this study DNA sequencing and SSCP (Single Stranded Conformation Polymorphism) analysis were performed to discover allelic diversity of genes related to iron chlorosis tolerance in citrus. Two iron chlorosis tolerance candidate genes were selected from existing Citrus ESTs databases and Arabidopsis thaliana genome databases. Ferritin-3 chloroplast precursor and putative membrane transporter candidate gene sequences were used to define primers in conserved regions. Six citrus genotypes from the basic taxon of Citrus where used to identify polymorphic areas in the genes. Direct sequencing of amplified DNA fragments of candidate genes was performed and SNPs (single-nucleotide polymorphisms) and InDels (Insertions/Deletions) where searched after sequence alignment. A total of 6840 bp DNA fragments were sequenced and 263 SNPs and 15 InDels were determined. New primers were defined, in conserved areas flanking polymorphic ones, for Single Strand Conformation Polymorphism (SSCP) analysis. SSCP-PCR analysis was performed with twenty-five Citrus genotypes. The neighbor joining method was used for cluster analysis. Phylogenetic origin of the alleles and genetic relationships of genotypes were discussed. (Texte intégral)