The Detailed Karyotype Analysis, Karyotype Asymmetry and Polyploidy in Hemp (Cannabis sativa L.)

Hemp (Cannabis sativa L.) is an economical plant with a diploid chromosome number of 2n = 20 and used in many areas, especially in industry. The aim of this study is to perform detailed karyotype analysis and detailed chromosomal measurements using five different genotypes of the plant known as diploid chromosome number 2n = 20, to determine the karyotype asymmetry for the first time, and to investigate the polyploidy variations. The diploid chromosome number and karyotype formula were 2n = 2x = 20 = 18m + 2sm. The karyotype had small metacentric and submetacentric chromosomes. The smallest chromosome length, largest chromosome length, total haploid chromosome length, and average haploid chromosome length were 2.41, 3.55, 29.87, and 2.99 μm, respectively. Intrachromosomal and interchromosomal karyotype asymmetries were calculated using many different parameters, mainly MCA (mean centromeric asymmetry) and CVCL (variation coefficient of chromosome length). According to the asymmetry values, the species had quite symmetrical karyotype. Although the diploid chromosome number was known as 2n = 20, detailed karyotype analysis and karyotype asymmetry data were presented for the first time by this study. In addition, in the study carried out on five different genotypes, polyploidy variation was detected in one genotype.