Exploring arbuscular mycorrhizal symbiosis in wetland plants with a focus on human impacts

Presence and functional roles of arbuscular mycorrhizal (AM) fungi in wetland environment have gained a global importance in recent past. Wetlands build a low-oxygen atmosphere, forming a completely different ecological environment for AM fungi, known more to occur in terrestrial environment. Nevertheless, as many 101 of AM fungi species, belonging to 19 genera and 9 families have been observed in the rhizosphere of wetland plants. In order to obtain oxygen, AM fungi expand the aeration system of wetland plants, store oxygen through their own vesicles, or change the structure of AM to survive. Human activities negatively affect the wetland environment, thus, reducing the population of AM fungi, while certain AM fungi species still improved the survival and development of wetland plants. AM fungi regulate different physiological activities of wetland plants in response to waterlogging stress, including an enhancement of antioxidant defense system, increased proline accumulation, improved plant growth and root morphology, responses of nutrients and aquaporins, and suppression in ethanol accumulation. The current review briefly summarized different species of wetland plants forming AM structures, the population of AM fungi inhabiting the rhizosphere of wetland plant, AM fungi-colonization of wetland plants, and the effect of AM fungi on physiological functions of wetland plants to neutralize the negative impact of waterlogging in addition to outlook of researchable issues. This review also highlighted human impacts on AM fungi of wetland plants and the impact of AM fungi on wetland environments and wetland plants.