title: Revision of ploidy status of Dioscorea alata L. (Dioscoreaceae) by cytogenetic and microsatellite segregation analysis.
abstract: Dioscorea alata is a polyploid species with several ploidy levels and its basic chromosome number has been considered by most authors to be x = 10. Standard chromosome counting and flow cytometry analysis were used to determine the chromosome number of 110 D. alata accessions of the CIRAD germplasm collection. The results revealed that 76% of accessions have 2n = 40 chromosomes, 7% have 2n = 60 chromosomes and 17% have 2n = 80 chromosomes. Progenies were produced from 2n = 40 types of D. alata and the segregation patterns of six microsatellite markers in four different progenies were analysed. The Bayesian method was used to test for diploid versus tetraploid (allo- and autotetraploid) modes of inheritance. The results provided the genetic evidence to establish the diploidy of plants with 2n = 40 chromosomes and to support the hypothesis that plants with 2n = 40, 60 and 80 chromosomes are diploids, triploids and tetraploids, respectively, and that the basic chromosome number of D. alata is x = 20. The findings obtained in the present study are significant for effective breeding programs, genetic diversity analysis and elucidation of the phylogeny and the species origin of D. alata.
authors.affiliation: Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Petit Bourg, Guadeloupe, France. gemma.arnau@cirad.fr
authors.forename: Gemma
authors.initials: G
authors.lastname: Arnau
authors.forename: A
authors.initials: A
authors.lastname: Nemorin
authors.forename: E
authors.initials: E
authors.lastname: Maledon
authors.forename: K
authors.initials: K
authors.lastname: Abraham
mesh_terms: D001499:Bayes Theorem; D020090:Chromosome Segregation; D032461:Chromosomes, Plant; D018556:Crops, Agricultural / Q000235:genetics; D003582:Cytogenetics / Q000379:methods*; D027742:Dioscorea / Q000235:genetics*; D005838:Genotype; D006801:Humans; D018895:Microsatellite Repeats; D011003:Ploidies