Variability in ploidy levels as a barrier for interspecific hybridization in Bromus species

Document Type : Research Paper

Authors

1 Research Institute of Forests and Rangelands, Tehran, Iran.

2 Researcher, Biotechnology Research Department, Research Institute of Forests and Rangelands

Abstract

Ten Bromus species were selected and planted in a field experimental layout to perform genetic variation, cytogenetic and interspecific hybridization studies. Interspecific hybridization was performed between several combinations of the species at an appropriate time which were not successful. Therefore, ploidy levels and other possible barriers were investigated. Several factors including non-overlapped flowering dates in field conditions, small size of flower components and variability in ploidy level were regarded as the main limiting factors of the interspecific hybridization. Various ploidy and aneuploidy levels in the studied species and populations were observed. The least number of chromosomes and ploidy level (2n=2x=14) were observed in Bromus sterilis, B.cappadocicus and B. inermis. The highest number of chromosomes and ploidy level (2n=84) were observed in B. tomentellus. A great number of the studied cells contained a high level of ploidy or a kind of aneuploidy. Populations with medium ploidy levels were also observed within the studied populations. A great number of differences were also observed between the size of the chromosomes of the studied populations and their karyotypic asymmetric.

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References

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