Epigenetic aspects of floral homeotic genes in relation to sexual dimorphism in the dioecious plant Mercurialis annua

Janardan Khadka, Narendra Singh Yadav, Micha Guy, Gideon Grafi, Avi Golan-Goldhirsh

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


In plants, dioecy characterizes species that carry male and female flowers on separate plants and it occurs in about 6% of angiosperms; however, the molecular mechanisms that underlie dioecy are essentially unknown. The ability for sex-reversal by hormone application raises the hypothesis that the genes required for the expression of both sexes are potentially functional but are regulated by epigenetic means. In this study, proteomic analysis of nuclear proteins isolated from flower buds of females, males, and feminized males of the dioecious plant Mercurialis annua revealed differential expression of nuclear proteins that are implicated in chromatin structure and function, including floral homeotic proteins. Focusing on floral genes, we found that class B genes were mainly expressed in male flowers, while class D genes, as well as SUPERMAN-like genes, were mainly expressed in female flowers. Cytokinin-induced feminization of male plants was associated with down-regulation of male-specific genes concomitantly with up-regulation of female-specific genes. No correlation was found between the expression of class B and D genes and the changes in DNA methylation or chromatin conformation of these genes. Thus, we could not confirm DNA methylation or chromatin conformation of floral genes to be the major determinant regulating sexual dimorphisms. Instead, determination of sex in M. annua might be controlled upstream of floral genes by one or more sex-specific factors that affect hormonal homeostasis. A comprehensive model is proposed for sex-determination in M. annua.

Original languageEnglish
Pages (from-to)6245-6259
Number of pages15
JournalJournal of Experimental Botany
Issue number21
StatePublished - 18 Nov 2019


  • Chromatin
  • DNA methylation
  • Mercurialis annua
  • cytokinin
  • dioecy
  • epigenetics
  • feminization
  • floral homeotic gene
  • nuclear proteome
  • sex-determination

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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