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Gametic configuration and inheritance of SSR markers in tetraploid interspecific and intergeneric citrus somatic hybrids : S02P20

Kamiri M., Stift M., Srairi I., Chahidi B., Poullet T., Constantino G., Dambier D., Ollitrault P., Froelicher Y.. 2012. In : Navarro Luis (ed.). XII International Citrus Congress : Book of abstract. Riverside : ISC, p. 50-50. International Citrus congress "Citrus and health. 12, 2012-11-18/2012-11-23, Valence (Espagne).

Citrus somatic hybridization has become an integral part of citrus improvement programs worldwide. More than 100 somatic hybrids have been created by Cirad. Intra and interspecific somatic hybrids will be used mostly for the triploid scion breeding. Intergeneric somatic hybrids can have a direct application as rootstocks or be used as parents for sexual 'tetrazyg' breeding. To optimize the design of such breeding schemes, it is essential to have knowledge of the inheritance mode in such allotetraploid hybrids. The aim of the present study was to investigate the inheritance (disomic, tetrasomic or intermediate) in a citrus interspecific hybrid (Citrus reticulata x Citrus limon) and an intergeneric somatic hybrid (C. reticulata x Poncirus trifoliata). Two triploid populations were generated using the somatic hybrids as pollinators in crosses with the diploid 'Chandler' pummelo. The triploid progenies were genotyped with SSRs to infer the allelic constitution of the somatic hybrid gametes. A likelihood-based approach was used to estimate for each locus the proportion of disomic versus tetrasomic segregations. For the two somatic hybrids, intermediate inheritance was observed with a major tendency for tetrasomic segregation in the interspecific hybrid, but a tendency for disomic inheritance in the intergeneric hybrid. The implications of the observed inheritance mode for citrus breeding are discussed with special focus on heterozygosity restitution. (Texte intégral)

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