Mixed-ploidy in Iranian endemic Cymbopogon olivieri (Boiss.) Bor: A chromosomal and holoploid genome size study

Cymbopogon olivieri is one of the important species belonging to the family Poaceae. The natural habitat of this plant is tropical regions. In particular, it is distributed in tropical and subtropical regions of Africa, Asia, and America. Two species, C. olivieri and C. parkeri have been reported in Iran. The genus has been proven to possess antioxidant, antimicrobial, and antibacterial properties. Taxonomic identification and species classifying of Lemongrass is very difficult due to the ease of cross-breeding and the existence of a large number of species and races. This study aimed to study variations and clustering of 10 Iranian endemic populations of C. olivieri (Boiss.) Bor based on chromosomal and holoploid genome size features. The results of karyotype analysis clearly showed the mixed-ploidy. Among which, six populations were diploids (2n=2x=20), three tetraploids (2n=4x=40), and a hexaploid (2n=6x=60). The mean chromosome length (CL) was determined as 1.87 µm for diploids, 1.73 µm for tetraploids, and 1.25 µm for a hexaploid. The average holoploid genome sizes of the diploids, tetraploids, and a hexaploid were 4.42, 4.64, and 4.91 pg, respectively. These results may provide relevant information for Cymbopogon breeding studies.