Novel approaches for understanding conifer seed dormancy and germination

有些种子从母体植物中释放出来后，只要遇到有利的环境条件，就会立即发芽。然而，有些种子在有利的条件下无法发芽，即使它们是可行的。这些休眠的种子必须暴露在环境线索，如温暖干燥的条件下，潮湿的寒冷，甚至烟雾的休眠被终止。某些针叶树（树）种（如黄杉、西部白松和冷杉）的种子会出现明显的休眠，在传播时表现出较低的发芽能力。农业和林业依赖于表现出高发芽率的种子;因此休眠通常被认为是不期望的性状。以及开发工具，提高针叶树种子发芽，我们已经确定了一些因素，施加和维持针叶树种子休眠。在这方面，我们最引人注目的发现涉及发芽抑制剂脱落酸（阿坝）和一种称为ABI 3的蛋白质，它有助于传递阿坝信号。ABI 3蛋白控制许多对种子存活至关重要的事件。这包括食物储备的沉积、休眠的施加和种子组织对干燥的耐受性的获得。在树木中，ABI 3蛋白可以作为一个全局调节器，在其生命周期中调节所有关键的转变。本研究的主要目的是：（1）进一步了解ABI 3在树木生命周期的重要转变过程中的“守门人”作用：休眠-萌发、萌发-生长和营养生长-生殖生长（开花）的转变。(2)描述针叶树种子休眠和萌发的新调节剂。了解针叶树种深度休眠的机制将作为一个重要的模型，并将产生新的发现有关的进化保守或分化的基因和蛋白质参与这一关键的适应性特征。

Some seeds germinate immediately upon their release from the parent plant as long as they encounter favorable environmental conditions. However, some seeds fail to germinate under favorable conditions, even though they are viable. These dormant seeds must be exposed to environmental cues such as periods of warm-dry conditions, moist chilling, or even smoke for dormancy to be terminated. The seeds of certain conifer (tree) species (e.g. yellow-cedar, western white pine and true firs) develop pronounced dormancy, exhibiting a low capacity for germination upon dispersal. The agricultural and forest industries rely upon seeds that exhibit high germination; hence dormancy is generally considered an undesirable trait. As well as developing tools for improving conifer seed germination, we have defined some of the factors that impose and maintain dormancy of conifer seeds. Our most striking discoveries in this regard concern the germination inhibitor abscisic acid (ABA), and a protein called ABI3, which helps to relay ABA signals. ABI3 proteins control many events that are critical to seed survival. This includes the deposition of food reserves, dormancy imposition and the acquisition of a tolerance of seed tissues to desiccation. In trees, the ABI3 protein may function as a global regulator, acting to regulate all key transitions during its lifecycle. The objectives of the proposed studies are: (1) To further our understanding of the role of ABI3 as a "gatekeeper" during important transitions of the lifecycle of trees: the dormancy-to-germination, germination-to-growth, and vegetative growth-to-reproductive growth (flowering) transitions. (2) To characterize novel regulators of dormancy and germination in conifer seeds. Understanding the mechanisms underlying the deep dormancy of conifer species will serve as an important model and will generate novel findings concerning the evolutionary conservation or divergence of genes and proteins involved in this critical adaptive trait.