Meng Yongjie, Shuai Haiwei, Luo Xiaofeng, Chen Feng, Zhou Wenguan, Yang Wenyu, Shu Kai
Key Laboratory of Crop Ecophysiology and Farming System in Southwest China (Ministry of Agriculture), Sichuan Engineering Research Center for Crop Strip Intercropping System, Institute of Ecological Agriculture, Sichuan Agricultural University Chengdu, China.
Front Plant Sci. 2017 Jan 24;7:2021. doi: 10.3389/fpls.2016.02021. eCollection 2016.
Seed germination and early seedling establishment are critical stages during a plant's life cycle. These stages are precisely regulated by multiple internal factors, including phytohormones and environmental cues such as light. As a family of small molecules discovered in wildfire smoke, karrikins (KARs) play a key role in various biological processes, including seed dormancy release, germination regulation, and seedling establishment. KARs show a high similarity with strigolactone (SL) in both chemical structure and signaling transduction pathways. Current evidence shows that KARs may regulate seed germination by mediating the biosynthesis and/or signaling transduction of abscisic acid (ABA), gibberellin (GA) and auxin [indoleacetic acid (IAA)]. Interestingly, KARs regulate seed germination differently in different species. Furthermore, the promotion effect on seedling establishment implies that KARs have a great potential application in alleviating shade avoidance response, which attracts more and more attention in plant molecular biology. In these processes, KARs may have complicated interactions with phytohormones, especially with IAA. In this updated review, we summarize the current understanding of the relationship between KARs and SL in the chemical structure, signaling pathway and the regulation of plant growth and development. Further, the crosstalk between KARs and phytohormones in regulating seed germination and seedling development and that between KARs and IAA during shade responses are discussed. Finally, future challenges and research directions for the KAR research field are suggested.
种子萌发和幼苗早期建立是植物生命周期中的关键阶段。这些阶段受到多种内部因素的精确调控，包括植物激素以及光照等环境信号。作为在野火烟雾中发现的一类小分子，独脚金内酯（KARs）在包括种子休眠解除、萌发调控和幼苗建立在内的各种生物学过程中发挥着关键作用。KARs在化学结构和信号转导途径方面与独脚金内酯（SL）具有高度相似性。目前的证据表明，KARs可能通过介导脱落酸（ABA）、赤霉素（GA）和生长素[吲哚乙酸（IAA）]的生物合成和/或信号转导来调控种子萌发。有趣的是，KARs在不同物种中对种子萌发的调控方式不同。此外，其对幼苗建立的促进作用表明KARs在缓解避荫反应方面具有巨大的潜在应用价值，这在植物分子生物学中引起了越来越多的关注。在这些过程中，KARs可能与植物激素，尤其是与IAA存在复杂的相互作用。在这篇更新的综述中，我们总结了目前对KARs与SL在化学结构、信号通路以及植物生长发育调控方面关系的理解。此外，还讨论了KARs与植物激素在调控种子萌发和幼苗发育过程中的相互作用，以及在遮荫反应中KARs与IAA之间的相互作用。最后，提出了KAR研究领域未来面临的挑战和研究方向。
