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。用化学和基因工具操纵植物激素在绿色革命中起到了重要作用；对激素如何控制植物生长的更深入理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最近发现的一种名为strigolacone的植物激素，以及植物中一种控制种子萌发、幼苗生长和叶片形状的未知分子(KL)。生物传感器将在该项目中用于提纯KL，KL可能是一种新的激素，并将用于识别产生KL的基因。KL的发现可能导致开发新的农用化学品或基因改造，以促进种子发芽和幼苗活力的统一，从而增加作物产量。Strigolacone传感器将是植物育种者的有用工具，使其能够更容易地培育出具有变化的strigolacone水平的作物，这反过来可能会影响作物的肥料需求及其对杂草的敏感性。本科生和博士后研究员将接受研究技能和科学交流方面的培训，从而加强科学队伍。研究发现将通过期刊出版物、新闻稿、新闻文章和当地演讲机会向公众传播。Karrikins是一种在烟雾中发现的化合物，可促进种子在火灾后萌发，并增强幼苗的活力。Karrikin信号通路与Strigolacone信号通路高度相似，提示有共同的祖先。Karrikin应答所必需的受体KAI2已被鉴定，但Karrikin不太可能是其天然配体。本项目的目标是：(1)建立灵敏和特异的生物检测方法，以检测未知的KAI2配体(KL)和链霉内酯；(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，作为其鉴定的垫脚石。将设计出基于转录或蛋白分解反应的Karrikins/KL和Strigollacones生物传感器。这些生物检测方法将被用于遗传筛选，以识别KL缺陷突变。最后，将使用生物测定引导的分级法从植物小分子提取物中分离KL。KL和KL生物合成基因的发现将催生一个新的植物生物学研究领域，影响对种子休眠、幼苗光形态建成和叶片发育的理解。它还将提供对KAI2信号机制在基础陆地植物中的祖先功能的洞察，该信号机制后来被复制和进化，以介导由木犀草酮控制的生长。

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.