Discovery of a Novel Signal that Enhances Germination and Seedling Growth

植物激素控制植物生长的方式和时间，以及植物对环境的反应。利用化学和基因工具操纵植物激素在绿色革命中发挥了重要作用；对激素如何控制植物生长的深入了解可能会推动未来农业的进步。在这个项目中，将开发生物传感器来检测一种最近被发现的植物激素——独角孤内酯，以及一种控制种子发芽、幼苗生长和叶片形状的未知植物分子（KL）。生物传感器将在这个项目中用于纯化可能是一种新型激素的KL，并识别产生它的基因。KL的发现可能会导致新的农药或基因改造的发展，促进种子发芽均匀和幼苗活力，从而提高作物产量。独脚金内酯传感器将成为植物育种者更容易培育出具有改变的独脚金内酯水平的作物的有用工具，这反过来会影响作物的肥料需求及其对杂草的敏感性。本科生和一名博士后将接受研究技能和科学交流方面的培训，从而增强科研队伍。研究发现将通过期刊出版物、新闻稿、新闻文章和当地演讲的机会传达给公众。Karrikins是在烟雾中发现的化合物，可以促进种子在火灾后发芽，增强幼苗活力。karrikin信号通路与独脚金内酯信号通路高度相似，表明它们有共同的祖先。karrikin INSENSITIVE 2 （KAI2）受体是karrikin反应所必需的，但karrikin不太可能是其天然配体。该项目的目的是：(1)开发敏感和特异性的生物检测方法来检测未知的KAI2配体（KL）和独角酯内酯，(2)鉴定与KL生物合成有关的基因，(3)从植物提取物中高度纯化KL，作为鉴定其的跳板。基于转录或蛋白水解反应的卡瑞金斯/KL和独角酯内酯生物传感器将被设计。这些生物测定将用于基因筛选，以确定缺钾突变体。最后，生物测定引导分离将用于分离植物小分子提取物中的KL。KL和KL生物合成基因的发现将催化植物生物学一个新的研究领域，影响对种子休眠、幼苗光形态发生和叶片发育的理解。这也将为了解基生陆生植物中KAI2信号机制的祖先功能提供新的见解，该信号机制随后复制并进化为介导独角藻内酯对生长的控制。

Plant hormones control how and when plants grow, and how plants react to their environment. Manipulating plant hormones with chemical and genetic tools has been instrumental in the green revolution; a deeper understanding of how hormones control plant growth will likely fuel future advances in agriculture. In this project, biological sensors will be developed to detect a recently recognized plant hormone called strigolactone, and an unknown molecule in plants (KL) that controls seed germination, seedling growth, and leaf shape. The biological sensors will be used in this project to purify KL, which may be a novel hormone, and to identify genes that produce it. Discovery of KL may lead to the development of new agrichemicals or genetic modifications that promote uniform seed germination and seedling vigor, thus increasing crop yields. Strigolactone sensors will be useful tools for plant breeders to more easily develop crops with altered strigolactone levels, which can in turn influence the fertilizer requirements of crops and their susceptibility to weeds. Undergraduate students and a postdoctoral researcher will be trained in research skills and scientific communication, leading to enhancement of the scientific workforce. Research discoveries will be communicated to the public through journal publications, press releases, news articles, and local speaking opportunities.Karrikins are compounds found in smoke that promote seed germination after fire and enhance seedling vigor. The karrikin signaling pathway is highly similar to the strigolactone signaling pathway, suggesting common ancestry. A receptor that is necessary for karrikin responses, KARRIKIN INSENSITIVE 2 (KAI2), has been identified, but karrikins are unlikely to be its native ligand. The aims of this project are to (1) develop sensitive and specific biological assays to detect the unknown KAI2 ligand (KL) and strigolactones, (2) identify genes involved in KL biosynthesis, and (3) highly purify KL from plant extracts as a stepping stone toward its identification. Biological sensors for karrikins/KL and strigolactones based on transcriptional or proteolytic responses will be engineered. These bioassays will be used in genetic screens to identify KL-deficient mutants. Finally, bioassay-guided fractionation will be used to isolate KL in small molecule extracts from plants. The discovery of KL and KL biosynthesis genes will catalyze a new field of research in plant biology that impacts the understanding of seed dormancy, seedling photomorphogenesis, and leaf development. It will also provide insights into the ancestral function of the KAI2 signaling mechanism in basal land plants, which later duplicated and evolved to mediate growth control by strigolactones.