Overexpression of a proton pumping gene OVP1 enhances salt stress tolerance, root growth and biomass yield by regulating ion balance in rice (Oryza sativa L.)

Abstract Oryza sativa vacuolar H+-pyrophosphatase 1 (OVP1) regulates plant development and osmotic stress response through its function as an electrogenic proton (H+) pump in the vacuolar membrane. Here, we show that OVP1-overexpressing transgenic (OTG) rice plants display greater resistance to salt stress and root growth than wild-type (WT) rice plants. This improved performance of OTG plants under salt stress was attributed to increases in vacuolar pyrophosphatase (V-PPase) activity, ion uptake, and vacuolar cation ion antiporter gene expression. OTG plants had higher sodium levels in the vacuole than in the cytosol. Under natural paddy field conditions, OTG plants outperformed WT plants and produced more extensive root systems. OTG plants also had higher tiller number, V-PPase activity, chlorophyll content, membrane stability, and ion uptake than WT plants. Transcript profiling analyses revealed that the expression levels of vacuolar H+-pump genes (ATPase and OVP1) and ion antiporter genes (CAX, MHX, and NHX) were higher in OTG plants than in WT plants. These combined results suggest that OVP1 overexpression affects salt stress responses, root development, and biomass yield by regulating ion balance in rice.