First karyotype analysis of Nerium oleander populations in Iran

Somatic chromosome numbers and karyotypes of five populations of Nerium oleander in Iran were determined. karyological studies showed that, all the studied populations were diploid (2n = 2x = 22). The present study is the first report of the karyotype characteristics of N. oleander. The highest values of mean chromosome length (1.45 µm) and haploid chromosome length (15.9 µm) were found in the Chabahar population. The general shape of the karyotypes, indicated symmetry for all populations, as all chromosomes were metacentric type. According to Stebbin’s classification (1971), populations fall in class 1A, thus indicating occurrence of chromosome symmetry among the populations. In addition, a detailed account of karyomorphology and estimates of asymmetry indices showed that, all of the populations were symmetric, among which Khash and Kuhdasht populations were considered as the most asymmetrical and symmetrical karyotypes, respectively. Based on karyotypic parameters, the considered populations were categorized into two groups viz. Chabahar, Fanuj, and Khash populations which were previously reported as N. indicum in Flora Iranica, separated from Karaj and Kuhdasht populations.