Novel Mycorrhiza-Specific P Transporter PvPht1;6 Contributes to As Accumulation at the Symbiotic Interface of As-Hyperaccumulator Pteris vittata

Abstract

Arsenic (As) is toxic and ubiquitous in the environment, posing a growing threat to human health. As-hyperaccumulator Pteris vittata has been used for phytoremediation of As-contaminated soil. Symbiosis with arbuscular mycorrhizal fungi (AMF) enhances As accumulation by P. vittata, which is different from As inhibition in typical plants. In this study, P. vittata seedlings inoculated with or without AMF were cultivated in As-contaminated soils for 2 months. AMF−root symbiosis enhanced plant growth, with 64.5% greater As contents in the fronds. After exposure to AsV for 2 h, the arsenate (AsV) and arsenite (AsIII) contents in AMF−roots increased by 1.8-and 3.6-fold, suggesting more efficient As uptake by P. vittata with AMF−roots. Plants take up and transport AsV via phosphate transporters (Phts). Here, for the first time, we identified a novel mycorrhiza-specific Pht transporter, PvPht1;6, from P. vittata. The transcripts of PvPht1;6 were strongly induced in AMF−roots, which were localized to the plasma membrane of arbuscule-containing cells. By complementing a yeast mutant lacking 5-Phts, we confirmed PvPht1;6′s transport activity for both P and AsV. In contrast to typical AMF-inducible phosphate transporter LePT4 from tomato, PvPht1;6 showed greater AsV transport capacity. The results suggest that PvPht1;6 is probably critical for AsV transport at the periarbuscular membrane of P. vittata root cells, revealing the underlying mechanism of efficient As accumulation in P. vittata with AMF−roots.

Insoluble-Phytate Improves Plant Growth and Arsenic Accumulation in As-Hyperaccumulator Pteris vittata: Phytase Activity, Nutrient Uptake, and As-Metabolism

“…While Pht1;1/1;2 are responsible for P acquisition in plants, showing little ability to uptake AsV, 43 Pht1;6 is often expressed at the plasma membrane of root cells in P. vittata during symbiosis with arbuscular mycorrhizal fungi. 44 In comparison, Pht1;3/1;4 exhibit strong AsV transport ability, responsible for efficient AsV uptake by P. vittata. 45,46 Furthermore, different from other Pht1, Pht1;4 expression is upregulated by As exposure, thereby mediating efficient P and As uptake under As exposure.…”

“…While Pht1;1/1;2 are responsible for P acquisition in plants, showing little ability to uptake AsV, Pht1;6 is often expressed at the plasma membrane of root cells in P. vittata during symbiosis with arbuscular mycorrhizal fungi . In comparison, Pht1;3/1;4 exhibit strong AsV transport ability, responsible for efficient AsV uptake by P.…”

Novel Phosphate Transporter-B PvPTB1;1/1;2 Contribute to Efficient Phosphate Uptake and Arsenic Accumulation in As-Hyperaccumulator Pteris vittata

“…9 Further, PvPht1;6 is the only mycorrhiza-specific Pht1 in P. vittata, which plays a crucial role in AsV uptake at the symbiotic interface in the roots. 8 In addition to its high AsV uptake capability, P. vittata also has a strong P-utilization efficiency. P. vittata prefers to grow in alkaline soils, showing an ability to thrive under low-P conditions.…”

“…Further, PvPht1;6 is the only mycorrhiza-specific Pht1 in P. vittata, which plays a crucial role in AsV uptake at the symbiotic interface in the roots …”

“…Recently, several key genes in P. vittata have been identified, including high-affinity P transporters Pht1 contributing to its efficient AsV uptake, − arsenate reductases HAC for tissue-dependent AsV reduction, , and AsIII antiporters ACR3 for efficient AsIII transport and sequestration. − Among these critical steps, its efficient AsV uptake is mediated by Pht1 in P. vittata.…”