Selenium Alleviates Carbohydrate Metabolism and Nutrient Composition in Arsenic Stressed Rice Plants

Abstract

This study reported the influence of selenium (Se) on carbohydrate composition and some related enzymes and nutrient compositions of arsenic (As) stressed rice plants. Rice plants of cultivar PR126 were grown on soil amended with As in a range of 25–100 μmol/kg with and without 0.5 or 1.0 mg/kg Se. Total soluble sugars (TSS) and reducing sugars (RS) increased in leaves of As stressed plants at the tillering and grain filling stages whereas sucrose and starch contents showed the reverse trend. Se supplementation to As stressed plants further increased TSS and RS, and enhanced sucrose phosphate synthase activity in rice leaves, thus improving sucrose content and the tolerance to As stress of the plants. Se alone or in combination with As resulted in lower As accumulation in rice husk and grains, and the highest reduction was observed in Se applied at 1.0 mg/kg compared to the corresponding As treatments alone. As may limit the accumulations of Na, Mg, K, Ca, Fe, Zn and Mn in rice grains, which are essential for humans. Binary application of different combinations of As and Se protected the plants against As and increased the mineral content in rice grains. Addition of Se in As treated soil significantly alleviated As stress by enhancing grain yields compared to the corresponding As treatment. It is concluded that Se induced amelioration of the toxic impact of As in rice either by modulating carbohydrate composition and/or nutrient uptake is one of the mechanisms to alleviate As stress in plants.