Exploiting night-time traits to improve wheat yield and water use efficiency in the warming climate of North-western Mexico

Wheat is the most widely grown cereal crop in the world: over 35 % of humans are reliant on it as a staple food source. Yields (tonnes per hectare) of wheat are variable, depending on local climate and the availability of resources such as water. Due to factors such as an increasing human population and pressures on land use there is a need to continually improve the 'genetic yield' of wheat. However the annual yield gains are increasingly threatened by the double impact of rising atmospheric temperatures and lowered water availability caused by climate change. Vulnerable wheat producing regions, including Mexico, face lowered productivity and economic difficulties if wheat yields decline or fail as a result of adverse temperatures and/or water availability. Therefore generating wheat lines with increased water use efficiency and high temperature tolerance is critically important.

This project proposal aims to generate novel genetic and physiological information that is necessary to improve water use efficiency and heat tolerance of wheat in NW Mexico. High temperature and water availability have a clear negative relationship. Temperature is also a regulator of plant and crop processes, being central to the regulation of development. High temperatures can be a major source of stress, affecting photosynthesis, respiration, photorespiration and the generation of active oxygen.

Water is important for wheat yields in Mexico with up to 84 % of wheat in this country requiring irrigation. There is also strong evidence that the mean temperatures in NW Mexico are rapidly rising. However it is becoming clear that the minimum (NIGHT TIME) temperatures are contributing to yield decline in cereals. Despite this, most work has focussed on the effect of day time temperatures while very little is known about nocturnal traits and their genetic regulation. Here we focus on the puzzle of night time water loss and its relationship with increasing night time temperatures: it is known that wheat leaves can lose a substantial amount of water at night via transpiration (even under drought) and there is genetic variation for this trait. This project will overcome this knowledge gap by producing novel techniques for night time screening of promising wheat germplasm for night time transpiration. We will apply methods for manipulating nocturnal temperatures of experimental crops in the field in the Sonoran region.
This project will bring together expert groups: the University of Nottingham (UK) which has expertise in photosynthetic and root phenotyping of wheat crops; Instituto Tecnológico de Sonora with expertise in water and environmental science; The Earlham Institute (UK) for wheat genomic analysis. This partnership is necessary for this project to succeed and to apply results that will result in improved wheat lines for the NW Mexico region. We will develop new tools for night time phenotyping of wheat leaf conductance under different minimum temperatures and apply them to a genetically diverse panel of wheat in the field (Sonora) and in controlled environments (UK). We will characterise novel variation in night time (and day time) conductance, link this to yield in water- irrigated and water limited conditions. We will gain new understanding of the shoot and root physiological mechanisms that give rise to this interesting and important process, pinpointing any tradeoffs that may exist. Genotyping of these lines will give rise to markers that can immediately be used in breeding wheat that will be used to improve and maintain wheat yields in NW Mexico. Hence this project will be of immediate benefit to growers in this region and will be a substantial contribution to 'climate-proof' agriculture and the local economy.

Rising global population and pressures upon land use caused by urbanization and erosion mean that higher productivity is essential to meet food security needs by 2050. This project should result in a step change in resource use efficiency and yield for many vulnerable agroecological scenarios affected by climate change. Almost a billion people in the world are defined by the FAO as 'hungry'. A step change in yield would instantly alleviate this whilst for poor farmers it would help them to generate extra cash to lift them out of poverty and improve health and wellbeing. For the rest of the world it may result in a lowering of food prices which would benefit economies and prevent surplus depletion allowing security.
To enhance impact we will make all the tools produced by U.Nottingham (UoN) and co-produced with ITSON available for use as open source. This includes tools and techniques for night time conductance proxies (Gs(n)), field heating of wheat plots. In addition, the genetic analysis data (Genotyping, markers, RNAseq data) of the wheat populations will be made available.
What groups of people will benefit from this research and how will they benefit ?
1. Growers and consumers in the Sonora region
The main objective of this proposal is to directly benefit the communities in the Sonora region who require wheat varieties that are more tolerant to abiotic stress, largely as a result of climate change. With rapid throughput to breeders in Sonora and elsewhere these will directly benefit growers enabling them to have more stable yields, secure yields. This will have economic benefits and support the local economy of the region and other important local agricultural products such as beef production. Consumers in the Sonora region will benefit from greater food security, price security and a more certain local economy based on agricultural produce.
2. Growers and consumers in other regions
Semi arid regions are in desperate need of traits that can alleviate abiotic stress as a result of water shortages and high temperatures. The Yaqui Valley region is agroclimatically representative of 40 % of the developing world's wheat growing areas making it an ideal location for a study with implications for both local and global food security. Hence this project has direct applicability to wheat growers in other regions affected by climate change for the reasons mentioned above.
3. Commercial and public plant breeders in Mexico and elsewhere. Commercial and government plant breeders will be provided with a source of novel traits and the tools for selection. This project is focusses on wheat but is equally applicable to any crop because (Gs(n) has been observed in many species.
3. International science and agriculture-related organisations. These data may be incorporated into predictive models of crop yield that are utilized by Food and Agriculture Organisation and other organizations such as the Intergovernmental Panel on Climate Change e.g. crop yield forecasts under differing environmental scenarios and those that include semi arid regions are used in producing advice for policymakers which part determines government policy.
4. Agricultural businesses producing seed and crop treatments, agricultural consultancy agencies would benefit from an advance in our understanding of the factors that limit crop yield, crop productivity and resource use efficiency.
5. The public and environment. An improvement in crop yield or crop resource use efficiency results in the potential to reduce impact on the natural environment by reducing land cultivated and inputs of water.