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

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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.