Silicon induced mitigation of TCA cycle and GABA synthesis in arsenic stressed wheat (Triticum aestivum L.) seedlings

The metalloid arsenic (As) is considered to be biologically non-essential and major environmental concern to all organisms. The aim of our study was to evaluate whether silicon (Si) has ameliorative effects on growth, respiratory cycle and Gamma-Aminobutyric acid (GABA) synthesis in wheat (Triticum aestivum L. cv PBW 343) seedlings under arsenic stress. The experiments were performed in a completely randomized design with three repeats and two replicates for each treatment. The seedlings were subjected to different doses of arsenate As (V) (25, 50 and 100 mu M) with or without silicate (5 mM) in modified Hoagland's nutrient media for 21 days. Arsenate stress decreased seedling growth, activities of respiratory cycle enzymes particularly dehydrogenases while enhanced the levels of oxidative stress markers, Krebs cycle intermediates and GABA including activities of enzymes associated with GABA synthesis. Arsenate treatment disturbed the phosphate contents and impaired the respiratory process. Irrespective of arsenate concentrations, silicate administration substantially modulated the toxic effects of the metalloid in the test cultivar. Thus, silicon supplementation may emerge as a beneficial strategy to reduce potential health risks and might help to mitigate arsenic- induced stress in wheat seedlings. (C) 2018 SAAB. Published by Elsevier B.V. All rights reserved.