AAFC IWYP Aligned Call Stomata signalling pathways for increasing yield potential in wheat

Cereals feed the world, representing roughly half of the global caloric intake. World grain stocks are the most basic measure of food security. Grain consumption is increasing annually, and end-use for biofuel production is also on the rise, meanwhile the available agricultural land cannot accommodate these growing needs. The increasing demand for grain worldwide necessitates higher production, and higher yield potential. It is anticipated that doubling of grain yields for food production alone will be necessary to meet population demands by the year 2050.Further impacts of climate change confound this challenge by threatening yield stability. Canada is one of the top five global exporters of wheat, which is the largest Canadian cash crop with an annual value exceeding $5 billion, but the impacts of heat and drought have been observed with increasing frequency on the Canadian Prairies,and has also been a serious problem for many wheat exporters around the world, including Australia and the United States. Stomata are attractive targets to improve wheat yield in our changing world. First, they are key determinants of photosynthesis that regulate carbon capture through CO2 uptake, and photosynthesis is a rate limiting step to improving yield potential. Second, stomata are key structural features in transpiration. This means they are major players in WUE, but also in maintaining optimal leaf temperatures through evaporative cooling. Maintenance of leaf temperature is critical for wheat, due to its temperature sensitivity during anthesis and grain filling. Additionally, the cooling effect of transpiration in maintaining canopy temperature has also been implicated in WUE. Stomatal conductance has been directly linked with wheat grain yield,due to both increased CO2 diffusion for photosynthesis and increased evaporative cooling. While often there is a trade off between WUE and yield, optimizing stomatal patterning and increasing stomatal response to environmental cues can lead to improvements on both fronts. In this project, we will generate and screen genetic mutants in wheat with altered stomatal patterning (increased or decreased stomatal index) and altered stomatal behaviour for better yield potential, WUE and leaf/canopy temperature control. Gene-edited/TILLING lines showing the best yield potential in different field settings will be made available for rapid incorporation of non-GM mutants into wheat breeding programs in Canada, the UK and Australia. Phenotypic analyses from both greenhouse and field environments will be accompanied with molecular analyses to identify upstream/downstream elements of stomatal pathways to fine-tune our approach for higher yield potential and stability. Key alleles regulating stomatal pathways will be identified in wheat, a first important step in germplasm and marker development for improve yields through optimized respiration, carbon assimilation and transpiration. This work falls within the call priorities 'In collaboration with international partners, upstream trait discovery, trait development and fundamental science with the goal of increasing the genetic yield potential in wheat by 50% in the next 20 years', as it brings together international expertise and efforts to employ discovery and fundamental science to study genetic components of yield potential, combined with a strong applied element on trait and germplasm development which will bring rapid results for wheat producers in Canada and around the globe.

It has been estimated that increases of 50% will be required in the yield of grain crops such as wheat and rice if food supply is to meet the demands of the increases in the world population. There is clearly an urgent need to develop crop plants that yield higher outputs per unit area of land, without having to increase inputs of fertiliser or water. The overall aim of this research proposal is to use novel screening techniques to generate and screen genetic mutants in wheat with altered stomatal patterning (increased or decreased stomatal index) and altered stomatal behaviour for better yield potential, Water Use Efficiency and leaf/canopy temperature control. Using thermal imaging and Infra-red gas exchange analysis we will assess variation in stomatal responsiveness in the various anatomical and physiological mutants. Using chlorophyll fluorescence and IRGAs we will determine photosynthetic rates and capacity in the flag and determine the effect of alternated stomatal conductance on these processes. Gene-edited/TILLING lines showing the best yield potential in different field settings will be made available for rapid incorporation of non-GM mutants into wheat breeding programs in Canada, the UK and Australia. Phenotypic analyses from both greenhouse and field environments will be accompanied with molecular analyses to identify upstream/downstream elements of stomatal pathways to fine-tune our approach for higher yield potential and stability. Key alleles regulating stomatal pathways will be identified in wheat, a first important step in germplasm and marker development for improve yields through optimized respiration, carbon assimilation and transpiration.

The project contributes to the Food Security Strategic Priority of the BBSRC. A key impact delivered through conventional breeding programmes will be improvements in wheat varieties better adapted to different environments. Varieties with greater levels of productivity and water use efficiency will help meet essential targets in food security and sustainable food production in the UK and worldwide. The research addresses environmental sustainability of crop production through use of novel high-throughput phenotyping combined with genetic mapping to identify markers that can be applied in practical wheat breeding programmes. We propose to target different genes in the stomatal development and functional pathways using transgenic/mutagenic approaches to improve photosynthesis and yield potential in wheat, as part of a germplasm development initiative, and to better characterize these pathways in cereals.
Better understanding of the control of stomatal patterning and behaviour on dynamics, canopy temperatures and WUE in plant carbon gain will accelerate the development and manipulation of plants for more efficient photosynthesis, the process that ultimately drives productivity per unit cultivated land area. Breeding programmes that incorporate project findings will be better placed to develop varieties with improved stomatal patterning and physiology, and thus increased water use efficiency and greater carbon gain per unit of resource (water, land, nutrients) input. This contributes to the sustainability of food production. The main non-academic beneficiaries of this research will be the agri-biotech sector and commercial breeders, and in particular the agri-businesses that have programmes to increase yield of crop plants. The findings will also be important for policy-makers interested in developing novel strategies to achieve food security, as well as the public who will benefit from food security and better agricultural use of water resources. In the activities described within the we will develop and identify mutant and CRISPR germplasm fully characterized for stomatal phenotype, yield performance under different field environments, photosynthetic performance, leaf temperature and WUE. These lines will be made available to Canadian breeders participating on this project and breeders collaborating with international partners. Further to this, new knowledge will be delivered on stomatal development and activity in monocots, and more specifically in wheat. The upstream activities described in this proposal will identify new gene targets and provide opportunities to develop or identify germplasm with very specific sequence changes to optimize activity of different genes involved in stomatal patterning and aperture function for improved yield, without compromising plant type and agronomic traits.
The project will benefit the professional career development of the RAs in both the UK and Canada through the transfer of phenotyping and physiology skills from the UK to Canada. The RAs will be trained in a wide range of research skills, including gaining scientific practical skills in plant physiology and communication skills through the dissemination of the research.