Effects of arbuscular mycorrhizas on reproductive traits in sexually dimorphic plants: a review

Abstract

Most plant species grow in association with arbuscular mycorrhizal fungi in their roots forming arbuscular mycorrhizal (AM) symbiosis. The positive effects of this type of symbiosis on plant’s performance are well known and established. However, relatively little is known about how AM symbiosis affects plant reproduction, even though reproduction is probably the most important component of life history. This review begins with a summary of the existing data on plants with monomorphic breeding systems, as most of the research has been performed using hermaphroditic and monoecious plants. Later, the limited number of studies examining mycorrhizal effects on plants with dimorphic breeding systems is detailed. Finally, several key areas for future investigations are highlighted. These include examination of the incidence of sex-specific interactions in other plant species with dimorphic systems, the influence of AM symbiosis in seed germination and establishment in plants with different gender, or the study of the mechanisms behind the AM effects seen on plant reproduction. Evidence suggests that AM symbioses are beneficial for plants with monomorphic and dimorphic breeding systems, as AM symbioses improve both sexual and asexual reproduction. However, the effects observed strongly depend on both the plant and the AM fungus species involved. Plant interactions with AM fungi and the outcome of these interactions may further depend on the gender of the host: sex-specific patterns of root colonization and sex-specific benefits from AM symbioses have been reported in several plant species. However, the incidence and the importance of sex-specific relationships between AM fungi and plants are still largely unexplored.