Crosstalk between gibberellin and other signaling molecules in the regulation of seed dormancy

赤霉素（giberellin， GA）是植物产生的信号化合物之一，在极低浓度下影响广泛的发育过程，通常被称为“植物激素”。GA控制种子发芽或休眠的能力，这是由种子中存在的GA量和种子对GA的反应介导的。种子中过量的赤霉素，或种子对赤霉素的高反应，会引发过早发芽。相反，GA含量低或对GA反应低的种子不能发芽并处于休眠状态；休眠时间的减少通常与种子GA水平和反应的增加有关。GA的休眠控制还通过其与其他参与调节种子发芽能力的信号分子（如茉莉酸盐（JA）和活性氧（ROS））的串扰介导。种子通过不同的策略来调节GA水平和其他信号分子的反应，反之亦然，从而维持或失去其休眠状态。其中一些策略和相关的调控因素已经在双子科植物的种子中被确定，而对单子科植物，特别是小麦等谷物的这一现象的理解一直滞后。我的研究项目的总体目标是充分了解植物激素如何调节发育过程，以便通过基因操作来提高作物产量和质量。在此背景下，本研究的具体目标是确定小麦种子通过JA或ROS调控GA水平和响应的新策略，从而控制其在休眠和萌发之间的发育转换。本研究的结果不仅提高了我们对GA与ROS或JA之间的串扰如何调节休眠的认识，而且为进一步了解激素控制种子休眠和萌发的策略提供了新的途径。本研究结果还将为提高小麦在不同环境条件下种子发芽和成苗的成功率以及成熟种子对采前发芽的耐受性提供有力工具，从而提高产量和品质。此外，该研究将培养4名博士，1名硕士和5名本科学生，他们在植物生物学领域具有广泛的技能，使学员能够成功实现他们的职业目标，同时为加拿大对高素质植物生物学家的需求做出贡献。

Gibberellin (GA) is among the plant-produced signaling compounds that influence a wide range of developmental processes at very low concentrations, usually described as “plant hormones”. GA controls the ability of seeds to germinate, or to remain dormant, and this is mediated by the amount of GA present in the seed and seed response to GA. Excess amounts of GA in seeds, or high seed response to the GA, triggers premature germination. Conversely, seeds with low amounts of GA or low response to GA, fail to germinate and remain dormant; and dormancy loss is often associated with increased seed GA level and response. Dormancy control by GA is also mediated by its crosstalk with other signaling molecules that take part in the regulation of seeds' ability to germinate or not, such as jasmonate (JA) and reactive oxygen species (ROS). Seeds employ different strategies to mediate the regulation of GA level and response by other signaling molecules or vice versa, and thereby maintain or lose their state of dormancy. Several of these strategies and the associated regulatory elements have been identified in the seeds of dicots, and understanding this phenomenon has been lagging in monocots, particularly in cereals such as wheat. The overall goal of my research program is to understand how plant hormones regulate developmental processes in sufficient detail to enable genetic manipulation for enhancing crop yield and quality. Within this context, the specific objective of the proposed research is to identify new strategies used by wheat seeds to mediate the control of GA level and response by JA or ROS and vice versa, and thereby control their developmental switch between dormancy and germination. The outcomes of this study not only advance our knowledge of how dormancy is regulated by crosstalk between GA and ROS or JA but also provide new avenues to further increase our understanding of the strategies underlying hormonal control of seed dormancy and germination. The findings of this work will also provide powerful tools for improving the success of seed germination and seedling establishment under diverse environmental conditions and the tolerance of maturing seeds to preharvest sprouting, a serious problem in the production of wheat, thus enhancing yield and quality. Furthermore, this research will train 4 Ph.D., 1 M.Sc. and 5 undergraduate students with a wide range of skills highly valued in the area of plant biology, making the trainees well-positioned to succeed in their career goals while contributing to Canada's need for highly qualified plant biologists.