Elucidating CO2-control of H+-ATPase traffic impacting climate responses

The growth of plants is underpinned by fixing atmospheric carbon dioxide (CO2) and plays a crucial role as a carbon sink that helps mitigate global climate challenges. Stomata are the gates for gas exchange between the plant and the atmosphere and open to fulfil the demand of CO2 in photosynthesis. Photosynthesis sustains plant growth and powers all life on Earth. Stomatal control underpins the balance between carbon gain with water loss through the stomatal pore and is a focus for engineering of plant water use efficiency and carbon intake. Each stoma comprises two guard cells around a central pore in the epidermis. Changes in guard cell volume, associated with osmotic ion and water transport, regulate pore aperture. As in all eukaryotes, vesicle traffic in guard cells determines the populations of transporters, altering transport capacity and adjusting membrane surface area for dynamic changes in guard cell volume during stomatal movements. Plasma membrane H+-ATPases are primary transporters that energise membrane transport for stomatal movements. Studies from the past four decades suggest that H+-ATPase trafficking is an important factor in the regulation of their abundance and functions at the plasma membrane, but underlying mechanisms remained elusive. Our recent work suggests that Arabidopsis H+-ATPase AHA1 trafficking pathways affect stomatal responses to CO2 and that these pathways associate with at least one novel regulatory protein that binds the H+-ATPase. How does AHA1 trafficking sense CO2, and what is the impact on stomata? We propose here to resolve these challenges and to explore the novel components in the mechanics of membrane traffic control in eukaryotes. Addressing these questions will build fundamental knowledge and facilitate a paradigm shift in thinking about membrane traffic and environmental responses feeding new strategies to safeguard crops. The project therefore falls within the remit of BBSRC Committee B (Plants, microbes, food and sustainability) and is relevant to the BBSRC's strategic priorities to "explore novel concepts that have the potential to transform our understanding of life" to gain fundamental knowledge that will aid in "improving efficiency through better understanding of relevant biological processes" and its applications to tackle "environmental and plant productivity" by offering insights to produce more robust crops to fulfil the "global demand for food" in a "challenging climate". The developments will therefore "provision national capabilities" and enable "scientific discovery" in plant biology. Our cross-disciplinary approach is facilitated by a diverse and experienced team, and we aim to build upon these strengths, developing cutting-edge research tools, and by offering training to staff and students at the forefront of research in the field. Thus, the project will facilitate BBSRC objectives "in creating and sustaining the conditions for dynamic, diverse and inclusive research". We anticipate to "build excellence in science" through a programme that underpins research that supports "technology development", "training" and "education" that meets BBSRC focus on people and training. We have established links with industrial/technology transfer partners, and as relevant, we will seek in the future to transfer the new knowledge into crops, and thus our efforts are timely and they underpin stated goals of the BBSRC in knowledge transfer for "sustainable agricultural productivity" in the face of global environmental change.