Karyological studies on different populations of several species of Agropyron in natural resources gene bank

To study karyological and relationship between 16 populations of genus Agropyron، namely Agropyron deserterum، A. tauri، A. repens، A. pectiniforme، and A. imbricatum (3 populations for each species،exceptfor A. imbricatum)، root meristem cells were used. Four suitable metaphase plates for each population were selected and photographed. Results showed، the basic chromosome number in all of the populations was x=7 and ploidy levels were 2x، 4x، and 6x. Results of analysis of variance revealed significant differences between the populations based on all karyotypic characteristics (P<%1) except for total form percentage (P<%5). This indicated occurrences of quantitative changes in chromosome size of the studied populations. Average size of the chromosome in the studied populations was 10. 518 micrometer. Using principal components analysis (PCA)، the first three independent components accounted about %93. 96 of total variation. The first component indicated that length of total chromosome، length of long arm، arm ratio، centromeric index، total form percentage، and intra chromosomal asymmetry index were important characters for classification of the populations with about 57% of total variation. By cutting dendrogram resulted from cluster analysis (Ward) in metric distance 2. 584، the populations were classified into 5 groups. The lowest metric distance was obtained between two populations، A. deserterum (15357)، and A. imbricatum (11389) and the highest metric distance was obtained between A. deserterum (629) and A. taur (327)، that indicates the least affinity between them. By a diagram of the genotypes dispersion، based on the two first components، the populations were grouped into 5 separated classes، which agreed to the results of cluster analysis.