Characterization; Genome Sizes and Morphology of Sex Chromosomes in Hemp (Cannabis sativa L.).

A dioecious plant, Cannabis sativa has two sex chromosomes (X and Y). The genome sizes of the diploid female and male plants were determined to be 1636 and 1683 Mbp, respectively, by flow cytometry. By the karyotype analysis, the X and Y chromosomes were found to be submetacentric and subtelocentric, respectively. The Y chromosome had the largest long arm with a satellite in the terminal of its short arm. Conspicuous condensation was specifically observed in the long arm and satellite of the Y chromosome during the prometaphase to metaphase stages. These results indicate that the Y chromosome, especially in its long arm, specifically differentiates in Cannabis sativa and might contribute to the sex determination.