Genetic and non-genetic sex determination in plants

Sexual reproduction arose at the dawn of the evolution of living beings and is a defining moment for Darwinian evolution and fitness. Its primary significance lies in the mixing of genes in a population and the creation of new genomic complexes in each new generation. From this perspective, the separation of individuals in a population by sex and the control of this separation are important attributes of sexual reproduction. Despite extensive research on the determination and control of sex expression in plants, this field of research remains relevant and less studied than in animals. This review discusses the current research and views on genetic and non-genetic sex determination in plants; the presence and role of sex chromosomes in dioecious species; sex-determining genes and downstream regulators; hormonal and epigenetic factors regulating sex expression; the influence of external and environmental factors; plasticity of plant sex expression and the transition from bisexual individuals to female and male and vice versa. The influence of sex-determining genes on the conserved floral meristem identity genes A, B, C, D and E, which ultimately express sex, is also considered.