Reproductive development in dwarf mistletoes (genus Arceuthobium): the male's tale, explosive seed discharge, and 'environmental' microscopy.

矮生槲寄生是一种寄生开花植物，侵染经济上重要的针叶树，严重危害它们的健康。由于花粉的有效成熟、它的传播和种子的传播都决定了Arceuthobium作为一种寄生虫的成功，了解发育和扩散事件将确定最终可能制定控制程序的关键阶段。这项拟议的工作将使用在不列颠哥伦比亚省坎卢普斯附近收集的美洲弓根瘤菌(Arceuthobium Americanum)，目标是三个短期目标。在目标1中，将使用先进的显微镜工具来描绘花粉发育。我和我的学生将利用光学显微镜和透射电子显微镜来探索花药和花粉的发育解剖和形态。我们还将使用荧光显微镜(FM)和透射电子显微镜结合特定的抗体来确定花粉细胞壁化学的变化。在目标2中，将与德国达姆施塔特技术大学的Ralf Kaldenhoff博士和不列颠哥伦比亚大学的Carl Douglas博士合作，确定水通道蛋白(膜水通道)在种子传播中的作用。Arceuthobium是开花植物中的佼佼者，因为它们通过静水压从果实中强制释放单个种子。我们将在Arceuthobium中鉴定水通道蛋白基因，并使用实时聚合酶链式反应和原位定位来监测它们的表达。在目标3中，将用“环境”扫描电子显微镜(SEM)检查裂开的花药、截获的花粉、释放的果实和释放的种子的实时变化。通过加拿大创新基金会，我的实验室已经获得了一种能够在不同压力、温度和相对湿度下成像活标本的扫描电子显微镜。这个强大的工具将使关于花药、萌发花粉、成熟果实和种子实时事件的关键问题得到解答。拟议的工作将培训13名本科生和3名研究生，并提供可用于制定关于这种臭名昭著的森林害虫的管理决策的信息。

Dwarf mistletoes (genus Arceuthobium, Santalaceae) are parasitic flowering plants that infect economically important conifers, seriously compromising their health. As effective maturation of pollen, its dispersal, and seed dissemination all govern the success of Arceuthobium as a parasite, understanding developmental and dispersive events will identify key stages toward which a control program may ultimately be devised. The proposed work will use Arceuthobium americanum (the lodgepole pine dwarf mistletoe) collected near Kamloops, British Columbia and target three short-term objectives. In Objective 1, pollen development will be delineated using advanced tools for microscopy. My students and I will employ light microscopy (LM) and transmission electron microscopy (TEM) to explore developmental anatomy and morphology of anthers and pollen. We will also use fluorescence microscopy (FM) and TEM in conjunction with specific antibodies to determine changes in pollen cell wall chemistry. In Objective 2, the role of aquaporins (membrane water channels) in seed dispersal will be defined in collaboration with Dr. Ralf Kaldenhoff at Technische Universität Darmstadt, Germany and Dr. Carl Douglas at the University of British Columbia. Arceuthobium species are standouts among flowering plants, as they forcibly discharge their single seed from the fruit via hydrostatic pressure. We will identify aquaporin genes in Arceuthobium and monitor their expression using real-time PCR and in situ localization. In Objective 3, real-time changes in dehiscing anthers, intercepted pollen, discharging fruit, and released seeds will be examined with 'environmental" scanning electron microscopy (SEM). Through the Canada Foundation for Innovation, my lab has acquired an SEM capable of imaging living specimens under varying pressures, temperatures, and relative humidity. This powerful tool will enable critical questions regarding real-time events in anthers, germinating pollen, mature fruit, and seeds to be answered. The proposed work will train 13 undergraduate and 3 graduate students as well as contribute information that can be used to shape management decisions regarding this notorious forest pest.