Regulation of nitrogen and phosphorus absorption by plasma membrane H+-ATPase in rice roots under simulated acid rain

The recognition of adverse environmental impact of acid rain is a prerequisite for finding feasible approaches to alleviate such damage to plants. We studied the regulation of nitrogen and phosphorus absorption by plasma membrane H+-ATPase and its expression at transcriptional levels in rice roots exposed to acid rain under hydroponic conditions. At pH 5.0 and 3.5, acid rain increased activity of plasma membrane H+-ATPase by increasing transcriptional levels of OSA1, 4, 5, 6, 7, 8, 9, and 10 and promoted ammonium absorption. However, nitrates and phosphorus contents in roots were decreased by acid rain (pH 3.5) due to a decrease in the H+ gradient. At pH 2.5, acid rain decreased nitrogen and phosphorus content in roots by decreasing plasma membrane H+-ATPase activity and its expression at transcriptional levels (OSA1-OSA10) as well as synthesis of ATP and inhibited the growth. After a 5-day recovery (without acid rain), all the parameters in roots treated with acid rain (pH 5.0 or 3.5) were greater than the data measured during the exposure period. However, all the parameters in roots treated with acid rain (pH 2.5) could not be recovered because heavy acid rain caused irreversible inhibition on plasma membrane H+-ATPase activity. Hence, we concluded that plasma membrane H+-ATPase plays a role in adaptation of rice seedlings to acid rain by regulating the absorption of nitrogen and phosphorus.