水分胁迫诱导ABA在玉米旱后复水补偿生长过程中的作用机理

Crops frequently live in an environment of periodic water deficit and rewatering,surviving such an environment over a long evolutionary scale led crops to acquire mechanisms by which they can sensitively perceive incoming water status and regulate their physiology accordingly. The abscisic acid (ABA) is proven to be the stress-inducing plant hormone to mediates crops growth and triggers tolerance to water stresses,and it maybe conduct as a key active substances and chemical signals to regulate crop physiology in the following rewatering. The higher level of ABA maybe maintain higher activity in antioxidant enzymes to enhanced the ability of crops to adapt to bright light and high temperature, to regulate the photosynthetic stomatal exchange performance, and to improve photosynthetic efficiency and water use efficiency.The pot experiment will be set in the project.In the process of variable water environment in maize seedlings period, such as a water control process of the normal water supply -drought stress - rewatering. The dynamic changes of ABA for maize (including root,stem and leaves) will be determinated during the period of turning the drought to rewatering. The photosynthetic gas exchange characteristic parameters and chlorophyll fluorescence parameters will be determinated under different level of light intensity, CO2 and temperature.And the osmotic adjustment substances and antioxidant enzyme systems related to ABA to play the regulation role will be determinated. The aim is to define the relationship between water stress inducing ABA and stomatal aperture, transpiration, photosynthesis.Reveal the variation law of photosynthetic gas exchange,photochemical efficiency, and photoinhibition under higher level of water stress inducing ABA after rewatering. Clarify the mechanism of water stress inducing ABA to crop compensation growth after re-watering. This study will be useful to explore the the mechanism of crop compensation effect of after drought, and Promote the efficient use of limited irrigation water.

ABA是作物在水分胁迫下启动气孔关闭的信号物质和适应干旱的调节物质，胁迫解除后复水，ABA仍可能维持在较高水平，可能通过类似干旱信号传递途径，维持较高的抗氧化酶活性，增强作物对强光和高温的适应能力，调节光合气孔交换性能，提高光合效率和水分利用效率，在作物旱后补偿生长中发挥积极作用。本项目通过盆栽试验，在玉米苗期正常供水-干旱胁迫-复水的变水过程中，通过测定干旱和复水前后根茎叶ABA动态变化，不同光强、CO2浓度和温度下叶片光合气体交换特征参数和叶绿素荧光参数，与ABA作用有关的渗透调节物质、抗氧化酶活性，明确旱后复水植株ABA水平变化及其与气孔开度、蒸腾、光合的关系，揭示旱后复水较高水平ABA对光合气体交换能力、光能转化效率、抗光温抑制能力的作用规律，阐明水分胁迫诱导ABA在玉米旱后复水补偿生长过程中的作用机理。本研究是对作物旱后补偿效应机理的有益探索，对促进有限灌溉条件下水分高效利用有积极意义。

前期干旱胁迫的生理生化响应可提高作物对再次胁迫的适应性，在复水后也可能继续促进作物加速生长，ABA作为胁迫响应信号和激素有双重功能，在胁迫和复水后的生理生化响应过程中有关键作用。.以玉米豫玉22和元华5号为材料，采用3控水水平(正常供水、中度干旱、重度干旱)、2时段 (干旱、复水) 进行水分控制，测定干旱及复水条件下植株ABA含量、生长、光合、叶绿素荧光、抗氧化酶活性等。分析干旱和复水时植株ABA变化特征，光合气体交换等生理响应，抗氧化酶活性变化， ABA与生长和生理生化对胁迫和复水响应的关系。.叶片ABA在干旱后迅速提高并维持较高水平，豫玉22、元华5号最高达13.05 ug/g.FW和6.88 ug/g.FW，分别是对照的3.90倍、2.49倍。前期中度胁迫ABA在复水2-4天恢复，前期严重胁迫ABA没有恢复。中度干旱胁迫后复水豫玉22的Pn、gs和Tr分别达到对照的155.20%、166.63%、152.49%，前期严重干旱处理复水后略低。前期中度胁迫后复水元华5号最大净光合速率、表观量子效率和光饱和点较对照增加5.63%、13.11%和2.85%。.经历前期干旱胁迫的植株复水后，不论是表观生理指标如蒸腾速率、气孔导度、光合速率、表观量子效率、PSⅡ实际量子产量，还是反映生理潜力的最大电子传递速率、最大羧化速率、最大净光合速率、光饱和点，都有显著的提高。ABA参与胁迫时抗氧化酶合成诱导，对复水后植株生理活性提高、生理潜能增强有促进作用。ABA作为传导信号，控制气孔导度、影响光合活性以调节作物生长，ABA在胁迫时增加使生长减缓以保水，复水后植株生长迅速增加以充分利用水和光。玉米幼苗生理生化和生长对干旱胁迫和复水响应过程中， ABA在作物耐旱适应性以及旱后作物补偿加速生长中发挥重要调节作用。.前期严重干旱复水11天后ABA和光合速率、Fv/Fm同时维持在高于对照水平，说明复水后维持较高的ABA水平没有抑制光合，复水后反映作物光合潜力的几个指标也显著高于对照，说明以ABA响应胁迫引起的生理生化调节，可能在复水后继续发挥积极作用，这是本研究的创新性的结论。