Dioecy in Fruit Crops: The Gender Rise and Decline and Its Agronomic Impact

Sexuality is a main strategy to maintain genetic diversity within a species. While most animals have separate male and female individuals, plants are usually hermaphroditic. However, a minority have evolved dioecy, where males and females are distinct individuals. Because dioecious plant species occur in different phylogenetic lineages, it is believed that dioecious sex determination systems have independently originated many times during evolution. Recent evidence suggests that dioecy is not fixed but is often reversible. This is particularly important in fruit crop species as sexual reproduction is crucial to productivity. Dioecy in fruit crop species has therefore been studied in detail since molecular genetic tools have offered the opportunity to understand the molecular mechanisms behind this phenotypic trait and knowledge of this area is advancing rapidly. The identification of the genes and the molecular pathways that control dioecy have allowed artificial modifications of sexuality, such as the production of hermaphroditic genotypes from dioecy through genome editing approaches. However, the knowledge of the molecular control of dioecy is less advanced for other crop species, such as fig (Ficus carica), ginkgo (Ginkgo biloba), hops (Humulus lupulus), bayberry (Morella rubra), mulberry (Morus spp.) and pistachio (Pistacia vera).

This Research Topic is dedicated to:

- Studies of dioecy in fruit crop species (such as date palm, kiwifruit, mulberry, papaya, persimmon, pistachio, red bayberry and others) with emphasis on updated reviews on the evolution of dioecy in plants and the molecular mechanisms that control the establishment and the reversal of dioecy.

- Studies on the molecular control of dioecy for fruit crops, like kiwifruit (Actinidia spp.), papaya (Carica papaya), date palm (Phoenix dactylifera), and persimmon (Diospyros spp.), for which the genetic model for sex determination is known.

- Genome editing studies and reports on advanced research on transformation through other technologies for the species where the candidate genes are mapped and cloned.

This Research Topic aims to showcase new insights about dioecy to the scientific community. Contributions on species like grape (Vitis spp.) and others, where the original dioecy has reversed back to hermaphroditism, are equally welcome, especially where the molecular mechanisms that have driven the reversal of dioecy are elucidated. Finally, contributions related to domesticated dioecious species that are not grown for fruit are also welcome.