Roles of Arbuscular Mycorrhizas in Plant Phosphorus Nutrition: Interactions between Pathways of Phosphorus Uptake in Arbuscular Mycorrhizal Roots Have Important Implications for Understanding and Manipulating Plant Phosphorus Acquisition

Abstract

In this Update, we review new findings about the roles of the arbuscular mycorrhizas (mycorrhiza = fungus plus root) in plant growth and phosphorus (P) nutrition. We focus particularly on the function of arbuscular mycorrhizal (AM) symbioses with different outcomes for plant growth (from positive to negative) and especially on the interplay between direct P uptake via root epidermis (including root hairs when present) and uptake via the AM fungal pathway. The results are highly relevant to many aspects of AM symbiosis, ranging from signaling involved in the development of colonization and the regulation of P acquisition to the roles of AM fungi in determining the composition of natural plant assemblages in ecological settings and their changes with time.

Growth, mineral composition, fruit yield, and mycorrhizal colonization of feijoa in response to lime and phosphorus application

“…Phosphorus doses had no effect on the colonization intensity of the root cortex, nor on the content of arbuscules (Figure 4). Although not confirmed in the present study, increased P availability in the soil commonly leads to decreased mycorrhizal colonization (Nogueira & Cardoso, 2006;Balota et al, 2011;Smith et al, 2011). However, some tree species native to Brazil showed no decrease in mycorrhizal colonization due to increased P availability Mineral composition of the leaves in the soil (Siqueira & Saggin-Junior, 2001), which may be the case of A. sellowiana.…”

Colonization of Greek olive cultivars' root system by arbuscular mycorrhiza fungus: root morphology, growth, and mineral nutrition of olive plants

“…Plants under fi eld conditions may be colonized by many AMF taxa and the outcomes of these symbioses are determined by interactions between plant, fungal genomes and environmental conditions (e.g. soil pH and P) (Smith et al, 2011). Jin et al (2013) found that the mixed species AMF inoculant (G. irregulare, G. mosseae and G. clarum) performed better than the single species G. irregulare alone by promoting mycorrhizal colonization and fi eld pea (Pisum sativum L.) biomass.…”

Regulation of plants' phosphate uptake in common mycorrhizal networks: Role of intraradical fungal phosphate transporters

“…4 Plants associated with AMF exhibit a specific symbiotic phosphate uptake pathway, which begins at the extraradical hyphae in the soil, from where inorganic phosphate (Pi) is translocated toward the roots and released from the arbuscule into the periarbuscular space. 5 There, it is taken up across the plant's periarbuscular membrane by specifically induced phosphate transporters belonging to the Pht1 family of plant Pi transporter. 6 Remarkably, these mycorrhiza-induced phosphate transporters have been found to be crucial for mycorrhizal Pi acquisition in several studies using mutants with reduced or inhibited mycorrhiza-inducible transporter gene expression.…”

“…However, mechanisms of Pi release from fungus to the periarbuscular space are less-well studied and remain obscure up to now. 5 In order to reveal the role of fungal Pi transporter in mycorrhizal Pi pathway, expression of several fungal Pi transporters genes of Rhizophagus irregularis (strain TERI commercial) and Funeliformis mosseae (strain ISCB 22, both kept in our fungal strain collection 9 ) were investigated in roots of flax and sorghum of the model system used in previously published studies 3,4 (Table S1 and S2). We designed gene expression assays for different Pi transporters of F. mosseae (FmPT1, FmPT3, FmPT7) and R. irregularis (RiPT1, RiPT3, RiPT5, RiPT7).…”