The relation between mutualistic mycorrhiza and endophytic plant-fungus associations and their effect on host plants

Abstract

Aim. A review of the literature to establish the mechanisms of the main mutualistic interactions that are important for the potential application of symbiotic fungi as biofertilizers, bioprotectors and bioregulators for more sustainable and so-called greening agriculture, soil restoration and understanding the role of microsymbionts in natural ecosystems. Methods. Comparative analysis of scientific literature. Results. Root mycorrhization is a potent factor of plant growth intensification, metabolic processes activation and macro-organism development improvement. Mycorrhiza formation is notable for angiosperms and gymnosperms, yet many representatives of bryophytes, ferns, and mosses also reveal (other) close symbiotic relations with fungi. Mycorrhizal fungi account for about 10 % of identified fungal species, including essentially all of the Glomeromycota and substantial fractions of the Ascomycota and Basidiomycota. De- pending on the fungal structures and microsymbiont position in tissues or cells of the macrosymbiont, arbuscular, ericoid, arbutoid, monotropoid, orchid mycorrhiza and so-called ectendomycorrhiza, and ectomycorrhiza are distinguished. This review gives an overview of the signalling interaction between partners and the bidirectional mechanism of nutrient exchange or other mutual benefits. Conclusions. Microscopic saprophytic fungi, capable of penetrating plant roots and playing a critical role in plant adaptation to abiotic and biotic stressors, are of special interest in mutualistic symbioses. In addition, while forming mutualistic symbioses with plants, the saprophytic fungi promote bio- mass increase and enhance the food traits of plants. The type of interaction depends on both micro- and macrosymbiot; it may in some cases and for some organisms fluctuate from mutualistic, commensalistic to antagonistic, even parasitic interactions, demonstrating different stages of mutualism evolution and co-habitation and/or evolution of plants and fungi. A better understanding of the diverse roles of symbiotic microorganisms in ecosystems will improve the ways of their application in agriculture.