A SPX domain‐containing phosphate transporter from Rhizophagus irregularis handles phosphate homeostasis at symbiotic interface of arbuscular mycorrhizas

Abstract

Reciprocal symbiosis of > 70% of terrestrial vascular plants with arbuscular mycorrhizal (AM) fungi provides the fungi with fatty acids and sugars. In return, AM fungi facilitate plant phosphate (Pi) uptake from soil. However, how AM fungi handle Pi transport and homeostasis at the symbiotic interface of AM symbiosis is poorly understood.Here, we identify an SPX (SYG1/Pho81/XPR1) domain-containing phosphate transporter, RiPT7 from Rhizophagus irregularis. To characterize the RiPT7 transporter, we combined subcellular localization and heterologous expression studies in yeasts with reverse genetics approaches during the in planta phase.The results show that RiPT7 is conserved across fungal species and expressed in the intraradical mycelia. It is expressed in the arbuscules, intraradical hyphae and vesicles, independently of Pi availability. The plasma membrane-localized RiPT7 facilitates bidirectional Pi transport, depending on Pi gradient across the plasma membrane, whereas the SPX domain of RiPT7 inhibits Pi transport activity and mediates the vacuolar targeting of RiPT7 in yeast in response to Pi starvation. Importantly, RiPT7 silencing hampers arbuscule development of R. irregularis and symbiotic Pi delivery under medium-to low-Pi conditions.Collectively, our findings reveal a role for RiPT7 in fine-tuning of Pi homeostasis across the fungal membrane to maintain the AM development.

Arbuscular Mycorrhizal Fungi Contribute to Phosphorous Uptake and Allocation Strategies of Solidago canadensis in a Phosphorous-Deficient Environment

“…Recent studies also revealed that AMF possess various key genes involved in the phosphate response signal transduction pathway ( Salvioli et al, 2016 ; Venice et al, 2020 ). However, molecular mechanisms of phosphate transport and metabolism are still need further study ( Xie et al, 2022 ).…”

A Eucalyptus Pht1 Family Gene EgPT8 Is Essential for Arbuscule Elongation of Rhizophagus irregularis

“…AM-inducible plant PHT1 family P i transporters localized in the PAM are responsible for the P i uptake from the PAS; once the formation of arbuscules in symbiotic roots were blocked, the free P i within the intraradical mycelium (IRM) could not be transported to plant cells through the symbiotic interface, resulting in the accumulation of polyphosphate (polyP) in AM fungal vesicles ( 44 – 46 ). Therefore, to further investigate whether the knockdown of EgPT8 by RNAi affects P i transport in intraradical hyphae, we performed the expression analysis of the genes involved in the PHO pathway of R. irregularis in control and RNAi lines through qRT-PCR (Fig.…”

Effect of arbuscular mycorrhizal fungi and phosphorus on drought-induced oxidative stress and 14-3-3 proteins gene expression of Populus cathayana

“…Drought stress reduces the transfer of P from soil to roots and subsequently to stems by reducing the transpiration rate and altering the function of membrane transporters ( Cramer et al, 2009 ). But AM fungi inoculation can enhance all these parameters ( Xie et al, 2022 ). Our study found that the P content in leaves and roots of P. cathayana seedlings inoculated with AM fungi increased significantly with the P additional level under the WW and WD conditions, which was significantly higher than the no-inoculated seedlings.…”