Effect of Lanthanum on Plasma Membrane H+-ATPase in Rice (Oryza sativa) Under Acid Rain Stress

Abstract

Global food security is threatened by damage to crop production by acid rain. To alleviate acid rain damage, we studied the effects of lanthanum (La3+) (0.06 and 0.12 mmol L−1) on plasma membrane H+-ATPase in rice seedlings under acid rain stress (pH 3.5 and 2.5). Relative growth rate, intracellular H+, ATP content, the activity, and gene expression of plasma membrane H+-ATPase were measured to validate the association of La3+ and plasma membrane H+-ATPase. We found that 0.06 mmol L−1 La3+ increased the plasma membrane H+-ATPase activity in rice treated with acid rain (pH 3.5) by increasing transcript levels of OSA 1,OSA 5, and OSA 7 genes, and thus, beneficial to pump excess H+ out of cells by supplying ATP energy. Thus, the decrease in relative growth rate was alleviated because of the application of 0.06 mmol L−1 La3+, showing an antagonistic interaction of acid rain and La3+ (0.06 mmol L−1). Contrarily, the application of 0.12 mmol L−1 La3+ aggravated the decrease in relative growth rate of rice under acid rain by decreasing the activity and expression of plasma membrane H+-ATPase, showing a synergistic interaction of acid rain and La3+ (0.12 mmol L−1). These results indicate that La3+ at the proper concentration can enhance the tolerance of rice seedlings to acid rain stress by increasing the activity of plasma membrane H+-ATPase, whereas La3+ at a higher concentration can aggravate the damage caused by acid rain.