The circadian clock and stress adaptation in barley

缺水是当今中东农业面临的最大问题。发展抗旱作物是在有限水资源条件下维持粮食生产的主要先决条件。近年来对拟南芥的研究表明，生物钟是植物调控胁迫适应的重要机制，通过调节关键的生理和代谢途径。然而，昼夜节律性状对作物适应性和产量潜力的影响尚未得到分析。该项目的目的是阐明大麦生物钟变化的适应性意义；2)获得大麦生物钟的机制及其与代谢组和非生物胁迫的相互关系。在项目的第一阶段，我们已经成功建立了一个高通量系统，根据荧光(F)的变化来测量昼夜节律，并在野生大麦收集B1K中确定了时钟突变体。在项目的第二阶段，我们建议使用已确定的时钟变体来a)定义时钟的输出特性，如田间和受控条件下的生理和农艺性能（产量）；b)通过测试时钟响应非生物压力的可塑性来定义时钟的输入途径。此外，我们建议分析全球基因表达，碳代谢和生理的昼夜变化，以揭示时钟如何调节大麦对环境变化的反应。全球基因表达、碳代谢和生理的变化将被整合到一个全面的网络中，以确定生物钟的因果关系、输入信号和输出参数及其对性能的影响。新的基因/等位基因和种质资源可用于适应中东干旱环境的大麦的标记辅助选择，也将对适应温带气候变化的大麦的精准育种具有重要价值。

The scarcity of water is the greatest problem facing agriculture in the Middle East today. The development of drought resistant crops is a major prerequisite to sustain food production under limited water conditions. Recent studies in Arabidopsis have shown that the circadian clock is an important mechanism controlling stress adaptation in plants by regulating key physiological and metabolic pathways. However, the impact of circadian traits on adaptation and yield potential in a crop has not yet been analyzed. The aims of the proposed project are to elucidate the adaptive significance of variation in the circadian clock in barley and 2) to gain a mechanistic understanding of the barley circadian clock and its interrelationship with the metabolome and abiotic stress. In the first phase of the project, we have successfully established a high-throughput system to measure circadian rhythmicity based on changes in fluorescence (F) and identified clock mutants in the wild barley collection B1K. In the second phase of the project we propose to use the identified clock variants to a) define output traits of the clock such as physiological and agronomic performance (yield) in the field and under controlled conditions and b) to define input pathways into the clock by testing plasticity of the clock in response to abiotic stresses. In addition, we propose to analyse circadian changes in global gene expression, carbon metabolism and physiology to reveal how the clock regulates responses to environmental changes in barley. Variation in global gene expression, carbon metabolism and physiology will be integrated in a comprehensive network to identify causal relationships, input signals and output parameters of the clock and its effects on performance. Novel genes/alleles and germplasm resources can be used for marker assisted selection of barley adapted to dry environments in the Middle East and will be also valuable for precision breeding of barley adapted to climate change in temperate latitudes.