Karyotype analysis of eight cultivated Allium species

Farzaneh Pordel Maragheh,Bozena Kolano,Daniel Janus,Kamil Haliloglu,Magdalena Senderowicz

doi:10.1007/s13353-018-0474-1

Farzaneh Pordel Maragheh, Bozena Kolano + Show 3 more

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https://doi.org/10.1007/s13353-018-0474-1

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Abstract

The karyotypes of Allium, a genus that comprises many crops and ornamental plants, are relatively poorly studied. To extend our knowledge on karyotype structure of the genus, the chromosomal organization of rRNA genes and CMA/DAPI bands was studied. Fluorescence in situ hybridization using 5S and 35S rDNA probes and banding methods (silver staining and CMA3/DAPI staining) were used to analyze the karyotypes of eight cultivated Allium L. species. Analyzed Allium taxa revealed three different basic chromosome numbers (x = 7, 8, 9) and three different ploidy levels (diploid, triploid, and tetraploid). The rDNA sites chromosomal organization is reported the first time for the six species (A. moly, A. oreophilum, A. karataviense, A. nigrum, A. sphaerocephalon, A. porrum). The Allium species that were analyzed showed a high level of interspecies polymorphism in the number and localization of the rDNA sites. The fluorescence in situ hybridization patterns of 35S rDNA sites were more polymorphic than those of the 5S rDNA in the diploid species. Several groups of similar chromosomes could be distinguished among the chromosomes that had rDNA sites in the polyploid species. Each of the groups had three chromosomes (triploid A. sphaerocephalon L.) or four chromosomes (tetraploid A. porrum L.) suggesting their autopolyploid origin. In the genomes of four of the analyzed species, only some of the 35S rDNA sites were transcriptionally active. Fluorochrome banding revealed that the CMA3+ bands were associated with the 35S rDNA sites in all of the species that were analyzed, except A. fistulosum L. in which positive CMA3+ bands were detected in the terminal position of all of the chromosome arms. The rDNA sequences, nucleolar organizer regions (NORs), and CMA/DAPI bands are very good chromosome markers that allowed to distinguished from two to five pairs of homologous chromosomes in analyzed Allium species. The karyotypes of the studied species could be clearly distinguished by the number and position of the rDNA sites, NORs, and CMA/DAPI bands, which revealed high interspecific differentiation among the taxa.

Highlights

Farzaneh Pordel Maragheh and Daniel Janus contributed to this work.Communicated by: Barbara NaganowskaElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.The genus Allium L. comprises more than 800 species (Fritsch et al 2010), making it one of the largest monocotyledonous genus
The analyzed Allium showed a high level of variability in the number and localization of the rDNA sites, and each species showed a different pattern of the rDNA sites
Silver staining was only performed for the species that had more than one pair of 35S rDNA sites

Summary

Introduction

The genus Allium L. comprises more than 800 species (Fritsch et al 2010), making it one of the largest monocotyledonous genus. Allium consists of 15 monophyletic subgenera (Friesen et al 2006). Species analyzed in this study belong to subgen. Allium (A. porrum L., A. sativum L., and A. sphaerocephalon L.), subgen. Porphyroprason (A. oreophilum C.A. Mey), and subgen. Melanocrommyum (A. karataviense Regel; Gurushidze et al 2010; Friesen et al 2006). Allium is a variable group that is spread widely across the Holarctic region from the dry subtropics to the boreal zone (Li et al 2010; Friesen et al 2006). Many Allium species are economically important plants, including, e.g., the common onion (A. cepa L.), the bunching onion (A. fistulosum), leek (A. porrum), garlic (A. sativum), and many ornamental species

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