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Acta Prataculturae Sinica ›› 2015, Vol. 24 ›› Issue (11): 206-217.DOI: 10.11686/cyxb2015046

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Progress on sex differentiation in unisexual flower plants

GAO Ming, CHEN Yi-Cun, YANG Su-Su, LIU Ying-Guan, ZHU Hui-Ping, WANG Yang-Dong*   

  1. Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou 311400, China
  • Received:2015-01-21 Online:2015-11-20 Published:2015-11-20

Abstract: Sexual reproduction is a universal phenomenon in the world of eukaryotes, and sex differentiation and determination are major events in the evolutionary history of angiosperms. The production of unisexual flowers has evolved numerous times from hermaphroditic ancestors, resulting in dioecious (5%) and monoecious (7%) plant taxa. Through developmental process, two broad categories of unisexual flowers have been recognized; the former results from flowers that are bisexual at initiation and become unisexual by termination of the development of the androecium (or the male reproductive organs) or gynoecium (or the female reproductive organs) and the latter results from sex differentiation occurring before initiation of stamens and carpels. Attempts have been made to understand regulatory mechanisms for plant sex determination by investigating unisexual flowers. The determinants of sexual phenotype in plants are diverse and complicated, including sex-determining genes in monoecious plants, Zea mays (corn) and Cucumis sp. (cucumber and its relatives); sex chromosomes in Silene latifolia and Carica papaya, which ensure the stable segregation of sexual phenotypes by preventing the recombination of sex determining genes; epigenetic regulatory mechanism, which alter gene expression, and hormonal regulation in Z. mays and Cucumis sativus. Sex determination is generally regulated by interactions between hormones, genetics and epigenetic modification. However, many important questions remain to be answered on the regulatory mechanisms of sex determination and sex differentiation, for example why few sex determination genes have been cloned, why the proportion of species with sex chromosomes is low, the relatively small portion of the dioecious species that have sex chromosomes, and the major epigenetic maintainers in genotypic sex determination (GSD). The recent research aimed at understanding the regulatory mechanisms of sex determination and sex differentiation in unisexual flowers, including phenotype traits, genetic base, epigenetics and physiological mechanisms were reviewed in this paper. Challenges and strategies are proposed to provide an effective contribution to elucidate the regulatory mechanisms of sex determination and sex differentiation in plants.