Résumé
Since 1994, INRA and CIRAD-FLHOR are associated for an easy peeler citrus improvement program by selecting spontaneous triploid hybrids resulting from crosses between Clementine and other citrus species. These triploid plants arose from gametic cell fusion between a haploid gamete and an unreduced diploid one. It is essential Io identified the 2n gamete parent and the mode of nuclear restitution involved in the diplogamy. For this purpose we have used codominant molecular markers (isozymes, STMS) and dominant ones (RAPDs, AFLPs) to detect qualitative polymorphism and quantitative variations among DNA of more than 100 selected triploid citrus, We showed that codominant markers can be used Io détermine the 2n gamete parental origin and the mode of nuclear restitution, whereas, dominant markers can only be used Io estimate the mode of nuclear restitution. Among the analyzed triploid hybrids, we find that 2n ovum production is very frequent, and 2n pollen production seems to be rare (less than 2%), The mode of nuclear restitution which was identified by estimating homozygousity level among the triploid progenies is probably a Second Division Restitution (SDR). The implications of this origin of 2n gametes for easy peeler breeding strategies are discussed. (Résumé d'auteur)