Optimisation et application de la RAPD (random amplified polymorphic DNA) dans un programme de sélection récurrente chez le cotonnier (Gossypium spp.)

Abstract

Optimization and application of RAPD (random amplified polymorphic DNA) in a recurrent selection programme of cotton (Gossypium spp.).Using DNA extracted from différent wild and cultivated species of cotton, we analyzed and optimized the parameters for the random amplification of polymorphic DNA (RAPD). All the parameters have an effect on the final result but the concentrations of template DNA, magnésium chloride, deoxynucleoside triphosphates, and the température of dénaturation seem to be the most important factors. The optimization was performed by successive adjustements of the standard RAPD conditions and by taking into accourir the manufacturera' recommendations for each reagent. The optimized conditions were then used to assist an interspecific hybridization programme involving two allotetraploid trispecific hybrids [(Gossypium thurberi Tod. x G. sturtianum Will.) doubled x G. hirsutum L., designated by G405] and [(G. hirsutum x G. raimondii Ulbr.) doubled x G. sturtianum, designated by G376]. Both trispecific hybrids were backcrossed with three varieties (LPB5, NC8 and C2) of the cultivated upland cotton G. hirsutum. In RAPD analysis, thirty random decamer primera generated 375 RAPD markers. Analysis of genetic similarity from the RAPD data with UPGMA and Jaccard's distance revealed 78.3-78.7% similarity between the three varieties of G. hirsutum and 31.3-39.2% similarity between G. hirsutum and the wild diploid species (G. thurberi, G. raimondii and G. sturtianum). The genetic similarity within backcross 1 progenies showed values ranging between 63.2-78.0% for the cross G405 x LPB5, 75.0-80.4% for G405 x NC8, 63.9-82.2% for G405 x C2, 76.3-83% for G376 x C2 and 64.9-79.8% for the cross G376 x LPB5. This study allowed to choose within the first backcross progenies having the searched trait, those sharing the highest genetic similarity with the cultivated parent G. hirsutum. Résulta indicate that RAPD analysis can be used to accelerate the recurrent selection of interspecific matériels from backcrosses

Keywords

• RAPD
• optimization
• cotton
• Gossypium
• interspecific hybridization
• similarity
• dendrogram
• selection