title: Evidence for non-disomic inheritance in a Citrus interspecific tetraploid somatic hybrid between C. reticulata and C. limon using SSR markers and cytogenetic analysis.
abstract: Artificial tetraploid somatic hybrids have been developed for sterile triploid citrus breeding by sexual hybridization between diploid and tetraploid somatic hybrids. The genetic structure of diploid gametes produced by tetraploid genotypes depends on the mode of chromosome association at meiosis. In order to evaluate tetraploid inheritance in a tetraploid interspecific somatic hybrid between mandarin and lemon, we performed segregation studies using cytogenetic and single sequence repeat molecular markers. Cytogenetic analysis of meiosis in the somatic hybrid revealed 11% tetravalents and 76% bivalents. Inheritance of the tetraploid hybrid was analyzed by genotyping the triploid progeny derived from a cross between a diploid pummelo and the tetraploid somatic hybrid, in order to derive genotypes of the meiospores produced by the tetraploid. A likelihood-based approach was used to distinguish between disomic, tetrasomic, and intermediate inheritance models and to estimate the double reduction rate. In agreement with expectations based the cytogenetic data, marker segregation was largely compatible with tetrasomic and inheritance intermediate between disomic and tetrasomic, with some evidence for preferential pairing of homoeologous chromosomes. This has important implications for the design of breeding programs that involve tetraploid hybrids, and underscores the need to consider inheritance models that are intermediate between disomic and tetrasomic.
authors.affiliation: Unité de Recherche Multiplication végétative, CIRAD, San Giuliano, 20230, France.
authors.forename: Mourad
authors.initials: M
authors.lastname: Kamiri
authors.forename: Marc
authors.initials: M
authors.lastname: Stift
authors.forename: Ikbal
authors.initials: I
authors.lastname: Srairi
authors.forename: Gilles
authors.initials: G
authors.lastname: Costantino
authors.forename: Abdelhamid
authors.initials: A
authors.lastname: El Moussadik
authors.forename: Abdelaziz
authors.initials: A
authors.lastname: Hmyene
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bakry
authors.forename: Patrick
authors.initials: P
authors.lastname: Ollitrault
authors.forename: Yann
authors.initials: Y
authors.lastname: Froelicher
mesh_terms: D020090:Chromosome Segregation; D002957:Citrus / Q000235:genetics*; D020732:Cytogenetic Analysis; D018744:DNA, Plant / Q000235:genetics; D005819:Genetic Markers; D005838:Genotype; D006824:Hybridization, Genetic; D040582:Inheritance Patterns; D016013:Likelihood Functions; D008540:Meiosis; D018895:Microsatellite Repeats; D008957:Models, Genetic; D057891:Tetraploidy
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers