DISSERTATION RESEARCH: Evolution of Mangrove Seed Physiology

提案：9623313 PI：凯洛格和Farnsworth 全面了解种子干燥和休眠的机制，对于为农场、树木园、植物园和植物园制定适当的储存、种植和发芽方案至关重要。 花园和种子保存银行 本研究以四个独立的红树林家系种子为材料，研究了其脱水耐性的演化及其发育表现胎生和脱水现象。 休眠（正统）种子的胚通常在进入代谢静止期之前失去水分;相反，不耐干燥的“柠檬”种子没有休眠，有些种子在母体植物上胎生发芽。 虽然这种现象在高地被子植物中很少见，但在沿海红树林、水稻和湿林树木中经常出现，这对农业和种子保护具有重要意义。 我们假设干燥耐受不良 结果 从一个 的 三 另一种不相互排斥的进化修饰：（1）在胚胎发生过程中，植物激素脱落酸（阿坝）的水平降低（ABA控制着整个植物对洪水的渗透调节，以及正常生长条件下的休眠）。 种子）;（2）差异水平 维生素蛋白质、碳水化合物储备或其他激素 在柠檬种子中;（3）种皮、母体转移组织或胚/胚乳关系的解剖学改变，这可能使胚免受物理或生化发芽抑制剂的影响。 为了验证这些假设，我们将研究四个胎生红树林家族在种子发育和萌发过程中所共有的激素、生理和解剖学基础。 胎生物种的种子将与密切相关的非胎生分类群的种子进行比较，以确定在这种平行进化模式中是否一致地出现了种子结构和生理学上的相似的、功能上显著的变化。 这种综合的方法将阐明这种进化趋同的性质，在几个生物学 水平;阐明解剖学、激素生理学、蛋白质之间的关系 和 发育期糖代谢 胎生和正统的种子;并提供了一些激素在植物生活史进化中的作用的第一个文件。 这些关于多重相互作用的比较数据 因素 控制 种子 休眠 植物的繁殖和繁殖可以有效地为植物保护、繁殖和农业提供信息。

Proposal: 9623313 PI: Kellogg and Farnsworth A comprehensive understanding of mechanisms of seed drying and dormancy is critical to developing appropriate storage, planting, and germination protocols for farms, arboreta, botanical gardens, and seed conservation banks. The evolution of desiccation-intolerance, and its developmental manifestations, vivipary and recalcitrance, will be studied in seeds of four phylogenetically independent mangrove lineages. Embryos of dormant (orthodox) seeds normally lose water prior to entering metabolic quiescence; by contrast, "recalcitrant" seeds that are intolerant of desiccation show no dormancy, and some sprout viviparously on the parent plant. While rare among upland angiosperms, this phenomenon appears frequently among coastal mangroves, rice, and wet- forest trees, with important implications for agriculture and seed conservation. We hypothesize that desiccation- intolerance results from one of three alternative evolutionary modifications that are not mutually exclusive: (1) decreased levels of the plant hormone abscisic acid, ABA, during embryogenesis (which controls both osmotic adjustment of the whole plant to flooding, and dormancy in orthodox seeds); (2) differential levels of dehydrin proteins, carbohydrate reserves, or other hormones in recalcitrant seeds; (3) altered anatomy of the seed coat, maternal transfer tissues, or embryo/endosperm relationship that may free the embryo from influences of physical or biochemical germination inhibitors. To test among these hypotheses, we will examine the hormonal, physiological, and anatomical bases of desiccation-intolerance that are shared among four viviparous mangrove families, in a study of seeds through development and germination. Seeds of viviparous species will be compared with seeds of closely related, non- viviparous taxa to determine whether similar, functionall y significant changes in seed structure and physiology have arisen consistently in this pattern of parallel evolution. This integrated approach will elucidate the nature of this evolutionary convergence at several biological levels; clarify relationships between anatomy, hormonal physiology, proteins and sugar metabolism during development of viviparous and orthodox seeds; and provide some of the first documentation of the role of hormones in the evolution of plant life histories. These comparative data on multiple, interacting factors controlling seed dormancy and recalcitrance can usefully inform strategies for plant conservation, propagation, and agriculture.