Karyotype analysis of some Allium species in Iran

Abstract

The karyotypes of 10 species (15 accessions) of Allium from Iran were investigated using the squash technique and 1% (w/v) aceto-iron-hematoxylin stain. The basic chromosome number was x = 8, and only in A. giganteum (1) x = 7. Karyotypes of 14 taxa of Allium were diploid with 2n = 16; only A. macrochaetum was tetraploid with 2n = 32. Satellite chromosomes were seen in A. asarense. All karyotypes were symmetrical, consisting of metacentric and submetacentric chromosome pairs. Only A. caspium and A. stipitatum (1) had subtelocentric chromosomes. Karyotype analysis according to Stebbins categories placed the studied taxa in symmetric classes of 1A and 2A, indicating a symmetric karyotype. The results of the analysis of variance showed significant differences for total chromosome length (TCL), mean chromosome length (CL), long arm length (LA), short arm length (SA) and intrachromosomal asymmetry index (A1). The longest chromosome length was detected on A. asarense, A. elburzense, A. giganteum (3), A. rotundum and A. stipitatum (3) (17.9-19.7 μm), while A. ampeloperasum demonstrated the shortest value (8.2 μm). Results of cluster analysis based on chromosomal parameters classified the taxa into four groups using the unweighted pair group method with arithmetic mean (UPGMA). Using principal component analysis, the first three components determined 97.3% of the total variation. The grouping of the taxa based on the 2-D scatter plot using the first two principal components, corresponding to the results of the karyotypic characteristics.