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。用化学和遗传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更深入了解可能会推动农业的未来发展。在该项目中，将开发生物传感器来检测最近被认可的植物激素独脚金内酯，以及植物中控制种子萌发，幼苗生长和叶片形状的未知分子（KL）。该项目将利用生物传感器纯化KL，这可能是一种新的激素，并确定产生它的基因。KL的发现可能导致开发新的农用化学品或基因修饰，以促进种子均匀发芽和幼苗活力，从而提高作物产量。独脚金内酯传感器将是植物育种者更容易开发具有改变的独脚金内酯水平的作物的有用工具，这反过来可以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人员将接受研究技能和科学交流方面的培训，从而加强科学工作队伍。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传达给公众。Karrikins是在烟雾中发现的化合物，可促进火灾后的种子发芽，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，表明共同的祖先。Karrikin反应所必需的受体，Karrikin Insensitive 2（KAI 2）已经被鉴定，但Karrikin不太可能是其天然配体。本项目的目的是（1）开发灵敏和特异的生物测定方法来检测未知的KAI 2配体（KL）和独脚金内酯，（2）鉴定参与KL生物合成的基因，（3）从植物提取物中高度纯化KL作为鉴定的垫脚石。基于转录或蛋白水解反应的karrikins/KL和独脚金内酯的生物传感器将被工程化。这些生物测定将用于遗传筛选以鉴定KL缺陷突变体。最后，生物测定引导的分级分离将用于从植物中分离小分子提取物中的KL。KL和KL生物合成基因的发现将催化植物生物学研究的一个新领域，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KAI 2信号传导机制在基底植物中的祖先功能的见解，该机制后来复制并进化为通过独脚金内酯介导生长控制。

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.