Résumé
A diploid hybrid between Citrus clementina and C. sinensis (CDO) was used as male parent in 4x x 2x sexual hybridizations with tetraploid Fina clementine and Moncada mandarin as female parents to produce triploid hybrids. Unexpectedly, in addition to some triploids, a total of seventy-two tetraploid plants were obtained, 62 plants from Fina x CSO and ten from Moncada x CSO. SSR and SNP markers analysis releaved that recovered tetraploid plants were hybrids arising from unreduced pollen gametes. A maximum-likelihood methodology based on parental heterozygosity restitution (PHR) of markers close to the centromeres was used to identify the mechanism underlying 2n pollen gamete formation. Thirty five tetraploid hybrids were identified to arise from FDR (56%) and 18 from SDR (29%) mechanisms. Inconclusive data were obtained for nine tetraploid hybrids. The pattern of variation of PHR values of ten SSR and twi SNP markers located along linkage groups 1 and 2 confirmed our results at population level. To our knowledge this is the first report in citrus of progenies of tetraploid hybrids recovered from 2n pollen gametes and the first description of coexistence of two meiotic mechanisms (SDR and FDR) producing unreduced pollen gametes. (Texte intégral)