title: Molecular Cytogenetic Analysis of Cucumis Wild Species Distributed in Southern Africa: Physical Mapping of 5S and 45S rDNA with DAPI.
abstract: Wild Cucumis species have been divided into Australian/Asian and African groups using morphological and phylogenetic characteristics, and new species have been described recently. No molecular cytogenetic information is available for most of these species. The crossability between 5 southern African Cucumis species (C. africanus, C. anguria, C. myriocarpus, C. zeyheri, and C. heptadactylus) has been reported; however, the evolutionary relationship among them is still unclear. Here, a molecular cytogenetic analysis using FISH with 5S and 45 S ribosomal DNA (rDNA) was used to investigate these Cucumis species based on sets of rDNA-bearing chromosomes (rch) types I, II and III. The molecular cytogenetic and phylogenetic results suggested that at least 2 steps of chromosomal rearrangements may have occurred during the evolution of tetraploid C. heptadactylus. In step 1, an additional 45 S rDNA site was observed in the chromosome (type III). In particular, C. myriocarpus had a variety of rch sets. Our results suggest that chromosomal rearrangements may have occurred in the 45 S rDNA sites. We propose that polyploid evolution occurred in step 2. This study provides insights into the chromosomal characteristics of African Cucumis species and contributes to the understanding of chromosomal evolution in this genus.
authors.affiliation: Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Landscape Architecture, Warsaw University of Life Sciences-SGGW, Warsaw, Poland.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Yagi
authors.forename: Magdalena
authors.initials: M
authors.lastname: Pawełkowicz
authors.forename: Paweł
authors.initials: P
authors.lastname: Osipowski
authors.forename: Ewa
authors.initials: E
authors.lastname: Siedlecka
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Przybecki
authors.forename: Norikazu
authors.initials: N
authors.lastname: Tagashira
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Hoshi
authors.forename: Stefan
authors.initials: S
authors.lastname: Malepszy
authors.forename: Wojciech
authors.initials: W
authors.lastname: Pląder
mesh_terms: D000353:Africa, Southern; D002874:Chromosome Mapping; D028462:Cucumis / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D019143:Evolution, Molecular; D007211:Indoles; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D004275:DNA, Ribosomal; D007211:Indoles; C007293:DAPI