Expression of New Pteris vittata Phosphate Transporter PvPht1;4 Reduces Arsenic Translocation from the Roots to Shoots in Tobacco Plants

Abstract

Arsenic-hyperaccumulator Pteris vittata is efficient in As uptake, probably through phosphate transporters (Pht). Here, for the first time, we cloned a new PvPht1;4 gene from P. vittata and investigated its role in arsenate (AsV) uptake and transport in yeast and transgenic tobacco plants. On the basis of quantitative real-time polymerase chain reaction (qRT-PCR), PvPht1;4 was abundantly expressed in P. vittata fronds and roots, with its transcripts in the roots being induced by both P deficiency and As exposure. PvPht1;4 was localized to the plasma membrane, which complemented a yeast-mutant defective in P uptake and showed higher P transport affinity than PvPht1;3. Under AsV exposure, PvPht1;4 yeast transformants showed comparable tolerance as PvPht1;3, but higher As accumulation than PvPht1;2 transformants, indicating that PvPht1;4 had considerable AsV and P transport activity. However, in soil and hydroponic experiments, PvPht1;4 expressing tobacco lines accumulated 26−44 and 37−55% lower As in the shoots than wild type plants, with lower root-to-shoot As translocation. In the roots of PvPht1;4 lines, higher glutathione (GSH) contents and expression levels of GSH synthetase gene NtGSH2 were observed. In addition, the transcripts of AsIII− GSH transporter NtABCC1 in PvPht1;4 lines were upregulated. The data suggested that PvPht1;4 lines probably detoxified As by reducing AsV to AsIII, which was then complexed with GSH and stored in the root vacuoles, thereby reducing As translocation in transgenic tobacco. Given its strong AsV transport capacity, expression of PvPht1;4 provides a new molecular approach to reduce As accumulation in plant shoots.

The roles of membrane transporters in arsenic uptake, translocation and detoxification in plants

“…Another study also showed that heterologous expression of PvPht1;3 in tobacco increased As accumulation in the shoots by enhancing As(V) absorption and translocation (Cao et al, 2019). A recent study showed that PvPht1;4, a putative phosphate/As(V) transporter in P. vittata, had considerable As(V) and Pi transport activities when expressed heterologously in yeast (Sun et al, 2020). PvPht1;4 is abundantly expressed in P. vittata fronds and roots, with its expression in the roots being induced by both Pi deficiency and As(V) exposure (Sun et al, 2020).…”

“…A recent study showed that PvPht1;4, a putative phosphate/As(V) transporter in P. vittata, had considerable As(V) and Pi transport activities when expressed heterologously in yeast (Sun et al, 2020). PvPht1;4 is abundantly expressed in P. vittata fronds and roots, with its expression in the roots being induced by both Pi deficiency and As(V) exposure (Sun et al, 2020). These results suggest that both PvPHT1;3 and PvPHT1;4 may contribute to the enhanced capacity for As(V) uptake in P. vittata, although in planta gene knockout is needed to provide direct evidence.…”

Evolution of Abscisic Acid Signaling for Stress Responses to Toxic Metals and Metalloids

“…Therefore, we speculate that ABA may inhibit As(V) uptake through WRKY6-PHT1;1 route in Arabidopsis, which requires future investigation. It's also worthy to isolate and functionally characterize rice and brake fern homologs of AtWRKY6 in As(V) uptake because OsPT1, OsPT4, OsPT8, PvPHT1, PvPHT1;3, and PvPHT1;4 confer to As(V) accumulation and toxicity in rice and P. vittata, respectively, most likely via their role in As(V) uptake in roots (Kamiya et al, 2013;DiTusa et al, 2016;Wang et al, 2016;Cao et al, 2017;Ye et al, 2017;Cao et al, 2019;Sun et al, 2019). Arabidopsis NIP1;1, NIP3;1, NIP3;2, and NIP7;1 function in As(III) uptake and accumulation (Lindsay and Maathuis, 2017;Deng et al, 2020), however, the regulation of them being mediated by ABA is still elusive.…”

Arsenic Remediation through Sustainable Phytoremediation Approaches

“…Thus, for designing a phytoremediation strategy, a high biomass crop can be genetically engineered by overexpression of the candidate MIP genes, particularly NIP3;1, NIP7;1, PIPs, Lsi2 and PvTIP4;1, which could increase As uptake and translocation and lead to enhanced As accumulation in genetically engineered plants. P. vittata showed increased As(V) uptake due to the increased expression of PvPHT1;3 (a phosphate transporter) and higher affinity for As(V) over phosphate [139,140]. In P. vittata, As(III) is primarily sequestered into the vacuole by PvACR3 (Arsenic Compound Resistant 3), an arsenite effluxer localized the in plasma membrane of gametophyte, and its homolog is absent in angiosperm [141].…”