Arsenic uptake and toxicity in plants: integrating mycorrhizal influences

Abstract

Arsenic (As) contamination of soil and water is a global problem that impacts on many areas of biology. This review firstly covers aspects of soil chemistry and soil-plant interactions relevant to the ways plants take up As (particularly arsenate (As(V)) from aerobic soils, with especial attention to As-phosphorus (P) interactions. It then assesses the extent to which studies of plant As tolerance based on short-term uptake of As(V) from nutrient solutions can be extrapolated to longer-term growth in contaminated soil. Mycorrhizal symbioses are then highlighted, because they are formed by~90% of higher plants, often with increased uptake of phosphate (Pi) compared with non-mycorrhizal (NM) counterparts. It is therefore likely that mycorrhizas influence As(V) uptake. Published work shows that arbuscular mycorrhizal (AM) plants (the most common mycorrhizal type) have higher P/As ratios than NM plants, and this would be expected to affect sensitivity to soil As. We discuss ways in which higher P/As selectivity might result from differential operation of P and As uptake pathways in AM compared with NM plants, taking into account new understanding of P uptake mechanisms. We also give suggestions for future research required to increase understanding of mechanisms of As(V) uptake, and its interactions with plant P.

The Arbuscular Mycorrhiza Rhizophagus intraradices Reduces the Negative Effects of Arsenic on Soybean Plants

“…Arsenate is toxic to plants because it acts like phosphate and is transported through the plasmatic membrane by the phosphate carriers [9,10]. Once in the cytoplasm, arsenate replaces phosphate in the ATP to form ADP-As, which disrupts the cellular energy flux [11].…”

Water management, rice varieties and mycorrhizal inoculation influence arsenic concentration and speciation in rice grains

“…AMF essentially improve plant phosphorus (P) nutrition and growth, which could result in a higher P/As ratio and a dilution effect on As in mycorrhizal plants (Ultra et al 2007;Xia et al 2007;Dong et al 2008;Caporale et al 2014;Spagnoletti and Lavado 2015). Smith et al (2010), Christophersen et al (2012), and He and Lilleskov (2014) compared the root and mycorrhizal Pi/arsenate (As(V)) uptake pathways and confirmed the important role of AMF in plant resistance to As contamination. Moreover, As-tolerant fungi may provide additional benefits to host plants over non-tolerant fungi (Orlowska et al 2012).…”

Disruption ofptLPD1orptLPD2, Genes That Encode Isoforms of the Plastidial Lipoamide Dehydrogenase, Confers Arsenate Hypersensitivity in Arabidopsis

“…In the environment, As exists in both organic and inorganic forms. Arsenate [As(V)] is the principal inorganic form of As in aerobic soils, while arsenite [As(III)] is the main form found under anaerobic conditions (Marin et al, 1993; Hossner, 1995, 1996;Mandal and Suzuki, 2002;Masscheleyn et al, 2002).Both As(V) and As(III) are toxic to plants, inducing symptoms ranging from poor seed germination and inhibited root growth to death (Meharg and HartleyWhitaker, 2002;Lee et al, 2003;Ahsan et al, 2008;Smith et al, 2010). The modes of action of As(V) and As(III) differ, owing to their distinct chemical properties.…”

“…Both As(V) and As(III) are toxic to plants, inducing symptoms ranging from poor seed germination and inhibited root growth to death (Meharg and HartleyWhitaker, 2002;Lee et al, 2003;Ahsan et al, 2008;Smith et al, 2010). The modes of action of As(V) and As(III) differ, owing to their distinct chemical properties.…”

“…As(V) has been recently shown to enhance membrane fluidity, and thus membrane permeability, by binding and replacing phosphate or choline head groups (Tuan et al, 2008). The resulting damage to the membrane would disrupt the transport of mineral nutrients and water (Smith et al, 2010). As(V) can be promptly reduced in plants, including Arabidopsis (Arabidopsis thaliana), to As(III) by endogenous As(V) reductases, so that often more than 90% of As in plant cells is in the form of As(III) (Zhao et al, 2009).…”