Department of Life Sciences, Chung-Ang University, Seoul 156-756, Korea.
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Korea.
Plant Pathol J. 2013 Dec;29(4):471-6. doi: 10.5423/PPJ.NT.07.2013.0071.
Plants are frequently exposed to numerous environmental stresses such as dehydration and high salinity, and have developed elaborate mechanisms to counteract the deleterious effects of stress. The phytohormone abscisic acid (ABA) plays a critical role as an integrator of plant responses to water-limited condition to activate ABA signal transduction pathway. Although perception of ABA has been suggested to be important, the function of each ABA receptor remains elusive in dehydration condition. Here, we show that ABA receptor, pyrabactin resistance-like protein 8 (PYL8), functions in dehydration conditions. Transgenic plants overexpressing PYL8 exhibited hypersensitive phenotype to ABA in seed germination, seedling growth and establishment. We found that hypersensitivity to ABA of transgenic plants results in high degrees of stomatal closure in response to ABA leading to low transpiration rates and ultimately more vulnerable to drought than the wild-type plants. In addition, high expression of ABA maker genes also contributes to altered drought tolerance phenotype. Overall, this work emphasizes the importance of ABA signaling by ABA receptor in stomata during defense response to drought stress.
植物经常面临多种环境胁迫，如脱水和高盐度，因此它们已经发展出了精细的机制来对抗胁迫的有害影响。植物激素脱落酸（ABA）作为植物对缺水条件反应的整合因子，在激活 ABA 信号转导途径方面起着关键作用。尽管已经提出 ABA 的感知很重要，但在脱水条件下，每个 ABA 受体的功能仍然难以捉摸。在这里，我们表明 ABA 受体，吡喃并苯并二氮杂卓抗性蛋白 8（PYL8），在脱水条件下发挥作用。过表达 PYL8 的转基因植物在种子萌发、幼苗生长和定植过程中对 ABA 表现出超敏表型。我们发现，转基因植物对 ABA 的超敏反应导致气孔高度关闭，从而导致蒸腾速率降低，最终比野生型植物更容易受到干旱的影响。此外，ABA 标志物基因的高表达也导致耐旱性表型的改变。总的来说，这项工作强调了 ABA 受体在保卫反应中对气孔 ABA 信号的重要性。
