STOCOVAR · A combination of approaches from the molecular to the integrative plant level to understand the bases of stomatal responses to CO2 and their variability

A combination of approaches from the molecular to the integrative plant level to understand the bases of stomatal responses to CO2 and their variability

Understanding plant responses to rising atmospheric CO2 is of major interest given the necessity to select and develop new crop cultivars that will show resilience to climate change while maintaining yields. CO2 influences gas-exchange by controlling the aperture of the stomata, microscopic pores found on aerial surfaces of most plants. Their opening and closure controls CO2 uptake for photosynthesis and water vapour loss by transpiration. Photosynthesis and transpiration co-vary with the aperture and density of stomatal pores, depending on plant species, varieties and environmental conditions. In addition, photosynthesis and transpiration rates are codetermined by the leaf area, which is involved in light capture and is subjected to evaporation. Thus, plant productivity is positively coupled with water losses through stomatal characteristics and shoot development. This coupling has prompted plant scientists to define water-use efficiency (WUE) as the amount of biomass produced per unit of water used through transpiration. Plants respond to elevated CO2 levels by reducing stomatal aperture, and recent advances have shed light on the intracellular machinery responsible for this response. However, little is understood about the variability in stomatal responses to CO2, both among and within species. This project first aims at deciphering the main factors responsible for variations in stomatal responses to CO2 and their impacts on whole plant performance (growth and WUE). It specifically addresses (i) the CO2 response mechanisms that take place at the molecular level and its interplay with stress hormones that lead to stomatal closure when the CO2 level increases, and (ii) the molecular mechanisms mediating the repression of stomatal development when plants are growing under elevated CO2 concentrations. Another crucial question is how plants respond to CO2 when in combination with other environmental constraints. Soil water availability is considered the primary factor limiting growth and productivity and thus, there is a clear and obvious need to study its interactive effects with elevated CO2 on a range of plant water relations. Although CO2 is often predicted to stimulate the yield of crops, counteracting the negative impacts of drought on food production, the positive or negative outcomes of these combinations might actually depend on the intensity and timing of drought stress relative to the development of the crop. Here, we also aim at revealing whether and how the drought- and CO2- signalling cascades overlap and interact depending on the timing of drought to ultimately alter the trade-offs between carbon gain and water loss by leaves.

Data: CORDIS, © European Union