Environmental and hormonal control of seed development and germination

由于植物的无根性，它们面临着大量的生物和非生物胁迫，并进化出各种策略，通过这些策略，它们可以有效地平衡生长和防御胁迫。植物采用的一种策略是在任何给定时刻保持适当的激素平衡。植物激素是一种小分子，其信号通路相互作用，共同形成一个复杂的串扰网络，调节植物对环境胁迫的反应。激素脱落酸（ABA）在植物内部启动胁迫反应，抑制生长和促进各种胁迫下的生存至关重要。无论植物受到何种类型的压力，其结果都是能量剥夺，从而激活能量传感器来维持能量稳态。SnRK1（蔗糖非发酵相关激酶1）是酵母Snf1和哺乳动物AMPK能量传感器的植物同源物。值得注意的是，AMPK是一种代谢性肿瘤抑制因子，目前是癌症和糖尿病治疗和预防的靶点。SnRK1激活在代谢应激下诱导大量转录重编程以保存能量。尽管这些必需的激酶复合物在能量稳态中起着关键作用，但已知的靶点很少。SnRK1和ABA信号通路在应激反应中交叉以促进生存，然而，这种相互作用的机制尚不清楚。

Plants face a multitude of biotic and abiotic stresses due to their sessile nature and have evolved various strategies through which they can effectively balance growth and defense against stressors. A strategy employed by plants is to maintain an appropriate hormone balance at any given moment. Plant hormones are small molecules whose signaling pathways interact, together forming a complex crosstalk network that regulates the plant's response to environmental stressors. The hormone abscisic acid (ABA) is critical for initiating a stress response within the plant, inhibiting growth and promoting survival under various stresses. Regardless of the type of stress that plants are exposed to, the result is energy deprivation that activates energy sensors to maintain energy homeostasis. SnRK1 (Sucrose non-fermenting Related Kinase1) is the plant ortholog of yeast Snf1 and mammalian AMPK energy sensors. Notably, AMPK is a metabolic tumour suppressor, currently a target for cancer and diabetes treatment and prevention. SnRK1 activation induces large transcriptional reprogramming under metabolic stress to conserve energy. Despite the pivotal role of these essential kinase complexes in energy homeostasis, few targets are known. SnRK1 and ABA signaling pathways intersect during stress responses to promote survival, however, the mechanism of this interaction is unclear. Seeds constitute up to 70% of our food intake, as direct consumption and animal feed. The proposed research program aims to understand how hormones regulate plant responses to environmental cues, with a focus on seed development and early vegetative growth. A combination of molecular genetics and targeted systems biology approaches will be used to: a) study the mechanism of hormone crosstalk during seed development and germination under abiotic stresses; b) understand the mechanisms of interaction between the SnRK1 and ABA signaling pathways, both of which are activated during stress; c) identify novel regulators of seed development and germination under abiotic stresses. In the long term, we aim to understand how plants integrate endogenous signals and external cues to adapt to changing environments. Scarcity of fresh water and increasing temperature due to global climate change are major threats to food security. Plants ability to respond to environmental stressors is critical during reproductive development, at which time water and heat stresses, especially when combined, can severely reduce seed filling and cause great yield losses. This is a great concern in Canada, where increasing temperature and drought have negatively impacted the yield of important agricultural crops, such as wheat, canola and corn in the past years. The knowledge gained from this program will aid in the future selection of plants with enhanced stress tolerance during seed development, greatly improving the yield of important agricultural crops.