Research progress of arbuscular mycorrhizal fungi in paddy fields

Abstract:

Rice feeds nearly half of the world’s population, and it is also considered as the model host plant for studying the symbiosis between arbuscular mycorrhizal fungi (AMF) and non-legumes. The diversity and ecological roles of AMF in paddy fields have not been well understood for a long time due to the limitation of research methods. Studies have demonstrated that AMF are ubiquitous in paddy fields with the development of high-throughput sequencing technology in the last decade. The application of new techniques greatly promoted the research on the ecological roles of AMF and the interactions between AMF and rice in paddy ecosystems. In this review, we summarized the process of the establishment of arbuscular mycorrhizal (AM) symbionts, the diversity and influencing factors of AMF, and the ecological roles of AMF in paddy ecosystems. Furthermore, the potential application of AMF in rice cultivation and future research on the interactions between AMF and rice have been prospected. The establishment of AM symbionts depends on a series of complex signal recognition, exchange, and conduction between AMF and rice. The AMF colonization rate of rice plants is higher in the upland environment than that in the paddy environment, and it is affected by host plants, environmental factors, and cultivation management measures. AMF play a key role in regulating rice growth and nutrient absorption, resisting environmental stress, and reducing methane (CH₄) and nitrous oxide (N₂O) emissions from paddy fields. AMF can act together with other microorganisms to help rice absorb nutrients and resist environmental stresses. This paper reviews the research progress and development trends of AMF in paddy fields and discusses the inadequacy in this research field. In the future, efforts should be made to explore the relationship between the diversity and ecological roles of AMF, the mutual signal recognition between rice and AMF, and the molecular cascade reactions in the establishment and maintenance of AM symbiosis. Moreover, it is essential to understand the underlying molecular mechanisms of AMF promoting rice nutrient absorption, enhancing rice stress resistance, and reducing greenhouse gas emissions from rice fields.