The Comparative Analysis of the DNA Repeat Composition among Cannabis Sativa L., Humulus Lupulus L. And Humulus Japonicus Siebold & Zucc. With Heteromorphic Sex Chromosomes

Heteromorphic sex chromosomes are rarely found in plants. They were observed only in 47 species from phylogenetically distant families, suggesting that the evolution of sex chromosomes was independent in these species. It was shown that DNA repeat sequences are one of the major factors driving sex chromosomes evolution, and an accumulation or elimination of the repetitive DNA elements are closely linked with the formation of differences in the sex chromosomes. The goal of this study was to characterize the transposon composition in male and female plants of Cannabis sativa L., Humulus lupulus L. and Humulus japonicus Siebold & Zucc. For the first time, the male and female genomes of H. japonicus as well as male genomes of H. lupulus and C. sativa have been sequenced (there were no open data about them). The analysis of genome-wide sequencing data with using Repeatexplorer2 and author’s scripts was carried out. It was shown that accumulation of Ty3-gypsy may be associated with speciation in Cannabaceae family which is the opposite of the theory of speciation throw whole-genome duplication. Moreover, the sex-specific DNA repeat clusters in C. sativa and H. japonicus were found. The analysis also revealed that the concentration of Tekay, Retand and Ikeros repeats in the Y chromosome of C. sativa is lower than in the X chromosome and the Angela concentration is higher in the Y chromosome.