Chromosome pairing and B-chromosomes in some Aegilops (Poaceae) species and populations from Iran

Abstract

Abstract Chromosome pairing, chiasma frequency and distribution as well as chromosome segregation were analysed in 14 populations of three Aegilops species. Populations of A. tauschii and A. speltoides possessed . = 7 chromosomes (diploid), while populations of A. crassa possessed . = 14 and 21 (tetraploid and hexaploid). Tetraploid species showed diplontic behaviour and formed bivalents only while diploid species of A. speltoides showed the occurrence of quadrivalents and hexavalents possibly due to the outbreeding nature of this species and structural heterozygosity. Cluster analysis of meiotic data showed distinctness of the Aegilops species in their meiotic behavior, although significant variations were observed in the chiasma frequency and distribution among different populations of each species. Twenty- seven populations of 6 Aegilops species were screened for the presence of B-chromosomes. The occurrence of those in 4 species of A. triuncialis, A. umbellulata, A. tauschii and A. crassa is a new report. No statistically significant effect of B chromosomes on chiasma frequency and distribution was found.