The orchestration of ectomycorrhizal symbiosis: a review of fungal-produced symbiotic regulators and their functions.

Abstract

Ectomycorrhiza is a mutualistic symbiotic association formed between fungi and plants, which enhances the host plant's stress resistance and promotes plant growth. It plays an important role in forest ecosystems. A plethora of symbiotically active regulatory molecules are secreted throughout the continuum of ectomycorrhizal development, encompassing the period before physical contact between the fungi and their host plant roots to the maturation of the ectomycorrhizal symbiosis. However, our understanding of these substances is still limited. In recent years, as research in this field has deepened, several studies have documented that fungi release symbiotic regulatory substances, including fungal-derived plant hormones and small secreted proteins, which participate in the regulation of mycorrhizal formation. This article, from a fungal perspective, elaborates on the symbiotic regulatory substances secreted by ectomycorrhizal fungi into the surrounding environment or within the host plant. It further discusses the role of these substances in establishing symbiotic relationships with plants, aiming to offer novel insights for researchers in this field.