No abstract

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.

OsPIP1;2 overexpression enhances rice growth and grain yield by facilitating leaf CO2 diffusion, which increases the net CO2 assimilation rate and phloem sucrose transport.

Barley (Hordeum vulgare L.) is a typical ammonium ( NH4 + )‐sensitive crop species and exhibits a futile‐ NH4 + efflux from root cells. Plasma membrane (PM) H+‐ATPase is responsible for pumping H+ out of plant cells and providing the driving force for the transport of various substances. We hypothesized that PM H+‐ATPase is involved in this NH4 + efflux process of barley roots. Barley plants were cultivated in hydroponic solution with 1.0 mM NH4 + or 1.0 mM nitrate ( NO3 - ) as the sole nitrogen source. Plasma membrane vesicles were isolated from the root tips for analyses of the activity. Plasma membrane H+‐ATPase was tested by Western Blot. The transcription of PM H+‐ATPase genes was analyzed using qRT‐PCR. Proton and NH4 + efflux from barley roots was analyzed by scanning ion‐selective electrode technique. The results show that root and shoot growth was repressed by NH4 + nutrition when compared to NO3 - nutrition. Plasma membrane H+‐ATPase activity of barley roots under NH4 + nutrition was significantly higher than that under NO3 - nutrition. Methyl‐ammonium (MeA), a non‐metabolizable analog of NH4 + , had no significant effect on PM H+‐ATPase activity. The enhanced PM H+‐ATPase activity by NH4 + nutrition was consistent with a higher abundance of PM H+‐ATPase protein and higher transcription levels of six PM H+‐ATPase genes. By using the pharmacological agents vanadate and fusicoccin, a close linkage was observed between H+ efflux and NH4 + efflux from barley roots. Taken together, NH4 + nutrition stimulates PM H+‐ATPase activity, and this stimulation is possibly triggered by NH4 + assimilation in barley roots. NH4 + efflux from barley roots is associated with PM H+‐ATPase activity which could provide the driving force for NH4 + efflux. Ammonium efflux might be considered as a disposal strategy in barley roots which prevents NH4 + overloading the root cytoplasm.