Résumé
The sugarcane genome is characterized by high polyploidy and aneuploidy. Modern cultivars (2n=100-130) come from interspecific hybridization between the sugar producing species Saccharum officinarum (2n=80) and the wild species S. spontaneum (2n=40-180). We have begun to develop microsatellite markers to study this complex genome. Several small insert microsatellite (simple sequence repeats or SSR) enriched libraries have been constructed from the sugarcane variety R570. These include libraries enriched for each of the dinucleotide repeats GT and GA, and for a mixture of the tri and tetra-nucleotide repeats GCC, GAA, CAA, ATT, ACC, CATA, and GATA. The libraries contained over 1300 insert containing clones. An initial screening of these libraries revealed 64% and 34% enrichment for each of two GT libraries and 18% and 73% for the GA and mixed libraries respectively. Several clones from each of the libraries were sequenced to confirm the presence of the SSR and to establish the type and size of the repeat. Primers were designed and products successfully amplified from several of these clones. The corresponding loci were evaluated for polymorphism on denaturing polyacrylamide gels using 20 different cultivars of sugarcane as well as several S. officinarum and S. spontaneum clones. Products were visualized by autoradiography. The resulting patterns ranged from simple monomorphic patterns with few bands to highly complex patterns consisting of several alleles yielding overlapping "stutter ladders". The analysis of the cultivars is currently underway. (Texte intégral)