谷子苗期对田间自然干旱胁迫的生理生化及转录组动态响应模式

Foxtail millet is well known for its strong tolerance to drought stress, yet there is not much research on the mechanism, and most of related research was on the physiological and biochemical responses, even much less research at the molecular level, restricting the exploration and utilization of its drought tolerant genetic resources. We propose here to investigate the drought related physiological and biochemical responses and transcriptomic changes over different time points (based on meteorological factors including temperature, humidity and light, and soil temperature) around the clock under natural drought conditions in the field, using two landraces identified as strong and weak drought tolerance. Key genes related to the stress response would be identified by comparing the transcriptomes between the landraces and among the different time points, and their dynamic expression changes over much detailed time points would be investigated. The relationship between the dynamic responses (physiological and biochemical responses, and the changes of transcriptome and the expression of key genes) and the environmental and circadian factors would be studied to establish the drought response model in foxtail millet. This would add to our understanding of the drought tolerance in foxtail millet, lay the foundation for further study on the drought tolerance mechanism and exploration of the special drought genetic resources in foxtail millet.

谷子具有很强的抗旱性，然而对其抗旱机制的研究却较少，且多集中在生理生化响应方面，相关分子机制研究则更少，严重影响谷子抗旱基因资源的发掘与利用。而且生理生化或分子水平（单基因或转录组）的相关研究也多是采用水培或盆栽实验，不能够真实地反映自然状态下谷子对干旱胁迫的响应。因此，本项目拟在田间自然干旱胁迫状态下，筛选苗期抗旱性强和弱的谷子资源，根据苗期气象（温度、光照、湿度）与土壤温度特点确定昼夜取样时间点，分析抗旱相关生理生化指标以及转录组在抗性强弱材料之间差异以及不同时间点之间的动态变化；从转录组数据发掘干旱胁迫关键基因并在更多的昼夜时间点分析其表达动态变化；将生理生化变化、转录组及关键基因表达与时间点、气象与土壤因素进行相关分析，建立谷子干旱胁迫响应模式，更为准确地了解谷子对干旱胁迫的响应，为后续深入探索谷子抗旱机制、发掘谷子特有的抗旱基因资源奠定基础。

谷子是起源于我国的重要杂粮作物，具有耐旱、耐瘠薄、适应性强、水分利用率高等特点，在作物抗旱种质资源利用方面具有其独特的研究价值，近年来已逐渐成为开展C4和抗旱耐逆研究的模式植物。虽然谷子具有较强的抗旱性，但随着全球气候变暖、气温升高、可利用水资源的日益减少，谷物减产的现象将被进一步激化。所以充分了解谷子在干旱胁迫条件下的反应机制，发掘鉴定谷子抗旱相关因素和基因资源，对培育抗旱品种、提高产量和品质具有极为重要的理论和实践意义。本项目利用不同的干旱胁迫处理方法筛选鉴定谷子种质资源，确定了不同抗性的谷子品种。比较了抗旱与敏感谷子资源在不同时间点不同土壤因素条件下对干旱胁迫的生理生化响应情况，同时利用高通量转录组测序技术建立了品种间（横向）和不同时间点（纵向）谷子在干旱胁迫下的表达谱，通过差异表达基因的GO、KEGG分类和富集以及共表达网络分析，发掘了一批与抗旱及昼夜响应相关的关键基因。这些结果不仅为今后深入研究谷子抗旱分子机制提供了物质基础和理论依据，而且对于谷子分子育种工作具有重要的指导意义。