Effect of arbuscular mycorrhizal fungi on uptake of selenate, selenite, and selenomethionine by roots of winter wheat

Abstract

Ubiquitous in agronomic ecosystems, arbuscular mycorrhizal fungi (AMF) readily colonize winter wheat (Triticum aestivum L.), but the mechanisms of the fungi related to selenium (Se) uptake by the crop are still unclear. Wheat seedlings were inoculated with Glomus versiform or Funneliformis mosseae for 8 weeks. Both concentration- and time-dependent Se uptake in wheat colonized by AMF were investigated in hydroponic experiments supplied with selenate, selenite, or selenomethionine. Pot trials were also conducted to investigate the influence of mycorrhizal inoculation on the accumulation of Se in wheat. The present study showed that AMF had a significant (P < 0.001) effect on selenate and selenite uptake by the wheat roots in hydroponic experiments, but not for selenomethionine. Vmax for selenate and selenite uptake by mycorrhizal roots was increased by more than 1.85 times than those by non-mycorrhizal roots, from 55.93 to 179.6 nmol g−1 d.w. h−1 for selenate and from 860.3 to 1688 nmol g−1 d.w. h−1 for selenite. Pot trials further showed that inoculation with AMF significantly (P < 0.05) enhanced Se accumulation in shoots and roots either in selenate- or selenite-spiked soils. Mycorrhizal inoculation significantly increased uptake of selenate and selenite by increasing the valid absorption area of roots, including specific root surface area, specific root length, and specific number of tips for Se uptake. The present study also suggested that AM symbiosis can improve wheat Se acquisition through up-regulating the expression of TaSultr1;1, TaSultr1;3, and TaSultr2;1 in the plant roots, especially TaSultr1;1. The enhanced Se uptake in the mycorrhizal roots benefits Se accumulation in wheat, indicating the potential of AMF to increase grain Se concentrations of wheat and to improve the diet of residents living on wheat as their staple food.