NIP1;2 is a plasma membrane-localized transporter mediating aluminum uptake, translocation, and tolerance in Arabidopsis

Abstract

Members of the aquaporin (AQP) family have been suggested to transport aluminum (Al) in plants; however, the Al form transported by AQPs and the roles of AQPs in Al tolerance remain elusive. Here we report that NIP1;2, a plasma membrane-localized member of the Arabidopsis nodulin 26-like intrinsic protein (NIP) subfamily of the AQP family, facilitates Al-malate transport from the root cell wall into the root symplasm, with subsequent Al xylem loading and root-toshoot translocation, which are critical steps in an internal Al tolerance mechanism in Arabidopsis. We found that NIP1;2 transcripts are expressed mainly in the root tips, and that this expression is enhanced by Al but not by other metal stresses. Mutations in NIP1;2 lead to hyperaccumulation of toxic Al 3+ in the root cell wall, inhibition of root-to-shoot Al translocation, and a significant reduction in Al tolerance. NIP1;2 facilitates the transport of Al-malate, but not Al 3+ ions, in both yeast and Arabidopsis. We demonstrate that the formation of the Al-malate complex in the root tip apoplast is a prerequisite for NIP1;2-mediated Al removal from the root cell wall, and that this requires a functional root malate exudation system mediated by the Al-activated malate transporter, ALMT1. Taken together, these findings reveal a critical linkage between the previously identified Al exclusion mechanism based on root malate release and an internal Al tolerance mechanism identified here through the coordinated function of NIP1;2 and ALMT1, which is required for Al removal from the root cell wall, root-to-shoot Al translocation, and overall Al tolerance in Arabidopsis.aquaporin | nodulin 26-like protein | aluminum tolerance | organic acid exudation | malate

Natural Amelioration of Mn-induced Chlorosis Facilitated by Mn Down-regulation, Ammonium and Rainwater in Sugarcane Seedlings

“…The first expanded leaf was collected randomly to determine the Mn and Fe contents, and 30 leaves were included in each sample. Separation of the cell sap of the first expand leaf was performed using the method described by Wang et al [8]. The Mn content in the leaves was analyzed with an atomic absorption spectrometer (PINAACLE900T; PerkinElmer, USA), after the leaves were cleaned, dried, and crushed according to the method published by Huang et al [7].…”

The ALMT Gene Family Performs Multiple Functions in Plants

“…Furthermore, AtALMT1 expression was induced by flg22, a kind of MAMP (microbe-associated molecular pattern) in a manner that was independent of the salicylic acid and jasmonic acid pathways [55]. A recent study with Arabidopsis, which also relies on malate efflux via a ALMT1 channel, proposes that the Al:malate complex is taken up by the root cells and transported to shoot by NIP1;2 to maintain low Al concentrations in the apoplast shoots [56]. These results indicate that AtALMT1 expression could contribute to plant-pathogen interactions [16] and that a single ALMT gene can perform multiple functions.…”

A multidrug and toxic compound extrusion (MATE) transporter modulates auxin levels in root to regulate root development and promotes aluminium tolerance

“…Plants secrete carboxylates like malate, citrate into the soil to chelate Al 3+ ions into nontoxic compounds, and prevent Al entry into plants (Delhaize et al, ; Kochian, Piñeros, Liu, & Magalhaes, ). A plasma membrane‐localized protein NIP1;2, a member of NIP subfamily, facilitates Al tolerance in Arabidopsis by root to shoot translocation of Al‐malate complex (Y. Wang et al, ). Similarly, MATE family of transporters are primarily involved in Al exclusion mechanism (Delhaize et al, ; Kochian, Piñeros, Liu, & Magalhaes, ; Remy & Duque, ; Ryan et al, ; Zhou, Delhaize, Zhou, & Ryan, ).…”

“…A plasma membranelocalized protein NIP1;2, a member of NIP subfamily, facilitates Al tolerance in Arabidopsis by root to shoot translocation of Al-malate complex (Y. Wang et al, 2017). Similarly, MATE family of transporters are primarily involved in Al exclusion mechanism (Delhaize et al, 2009;Kochian, Piñeros, Liu, & Magalhaes, 2015;Remy & Duque, 2014;Ryan et al, 2011;Zhou, Delhaize, Zhou, & Ryan, 2013).…”