Nitrogen (N) and carbon (C) are essential elements for plant growth and crop yield. Thus, improved N and C utilisation contributes to agricultural productivity and reduces the need for fertilisation. In the present study, we find that overexpression of a single rice gene, Oryza sativa plasma membrane (PM) H⁺-ATPase 1 (OSA1), facilitates ammonium absorption and assimilation in roots and enhanced light-induced stomatal opening with higher photosynthesis rate in leaves. As a result, OSA1 overexpression in rice plants causes a 33% increase in grain yield and a 46% increase in N use efficiency overall. As PM H⁺-ATPase is highly conserved in plants, these findings indicate that the manipulation of PM H⁺-ATPase could cooperatively improve N and C utilisation, potentially providing a vital tool for food security and sustainable agriculture.

ABI1 interacts with the C terminus of AHA2 and dephosphorylates Thr ⁹⁴⁷ to negatively regulate root growth and hydrotropism.

Aquaporins are involved in CO₂ transport from the leaf intercellular air space to the chloroplast, which contributes to CO₂ assimilation. However, the mechanism of CO₂ transport by rice (Oryza sativa L.) aquaporins is unknown. Here, we investigated the function of the aquaporin OsPIP1;2 in CO₂ diffusion-associated photosynthesis and phloem sucrose transport. Moreover, the grain yield of rice lines overexpressing OsPIP1;2 was determined. OsPIP1;2 was localized to the plasma membrane and the relative expression of OsPIP1;2 was approximately 5-fold higher in leaves in the presence of an elevated CO₂ concentration. Overexpression of OsPIP1;2 increased mesophyll conductance by approximately 150% compared with wild-type (WT) rice. The OsPIP1;2-overexpressing lines had higher biomass than the WT, possibly due to increased phloem sucrose transport. In addition, the grain yield of OsPIP1;2-overexpressing lines was approximately 25% higher than that of the WT in three-season field experiments, due to the increased numbers of effective tillers and spikelets per panicle. Our results suggest that OsPIP1;2 modulates rice growth and grain yield by facilitating leaf CO₂ diffusion, which increases both the net CO₂ assimilation rate and sucrose transport.