An Analysis of Chromosome Pairing Behaviour in Newly Synthesized Alfalfa Tetraploids by Means of SSR Markers
A duplication of a species’ chromosomes results in the formation of a polyploid with polysomic inheritance, or autopolyploid, while the union of the genomes of different species results in the formation of a polyploid with disomic inheritance, or allopolyploid. Cultivated alfalfa shows polysomic (tetrasomic) inheritance; however, no information of chromosome pairing behaviour is available for newly tetraploidized M. sativa. We are studying two tetraploid plants obtained by bilateral sexual polyploidization, that is, by crossing a diploid Medicago sativa subsp. falcata plant that produces 2n eggs (PG-F9) with a 2x Medicago sativa. subsp. coerulea x falcata plant that produces 2n pollen (12P). We are employing SSR markers to investigate the chromosome pairing behaviour of these two plants. They were crossed with an unrelated tetraploid pollen donor, and parental SSR allele segregation patterns are examined in the two progenies. Our results so far, indicate that random pairing, and consequently tetrasomic inheritance, is the rule in newly tetraploidized M. sativa.
KeywordsSexual Polyploidization Second Division Restitution Division Restitution Tetrasomic Inheritance Disomic Inheritance
Funding was provided by the Italian Ministry of University and Science, project: Sexual polyploidization in alfalfa: insight into gene expression changes in newly synthesized tetraploids, PRIN 2008 (prot. 2008AEAXRK_001, PI Fabio Veronesi).
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