Jing Tingting, Xing Qian, Shi Yunfeng, Liu Xuemei, Müller-Xing Ralf
College of Life Science, Northeast Forestry University, Harbin 150040, China.
Jiangxi Provincial Key Laboratory of Plant Germplasm Innovation and Genetic Improvement, Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang 332900, China.
Int J Mol Sci. 2024 Dec 12;25(24):13340. doi: 10.3390/ijms252413340.
Adventitious root (AR) formation in plants originates from non-root organs such as leaves and hypocotyls. Auxin signaling is essential for AR formation, but the roles of other phytohormones are less clear. In , at least two distinct mechanisms can produce ARs, either from hypocotyls as part of the general root architecture or from wounded organs during de novo root regeneration (DNRR). In previous reports, gibberellin acid (GA) appeared to play reverse roles in both types of ARs, since GA treatment blocks etiolation-induced AR formation from hypocotyls, whereas GA synthesis and signaling mutants apparently displayed reduced DNRR from detached leaves. In order to clarify this contradiction, we employed the GA biosynthesis inhibitor paclobutrazol (PBZ) and found that PBZ had positive effects on both types of AR formation in Consistently, GA treatment had negative effects on both AR formation mechanisms, while loss of GA synthesis and signaling promoted DNRR under our conditions. Our results show that PBZ treatment can rescue declined AR formation in difficult-to-root leaf explants such as receptor mutants. Furthermore, transcriptional profiling revealed that PBZ treatment altered GA, brassinosteroids, and auxin responses, which included the up-regulation of that is well known for its pivotal role in AR initiation.
植物不定根（AR）的形成起源于非根器官，如叶片和下胚轴。生长素信号传导对于不定根的形成至关重要，但其他植物激素的作用尚不清楚。在拟南芥中，至少有两种不同的机制可以产生不定根，一种是作为一般根系结构的一部分从下胚轴产生，另一种是在从头根再生（DNRR）过程中从受伤器官产生。在之前的报道中，赤霉素（GA）在这两种类型的不定根中似乎发挥着相反的作用，因为GA处理会阻断下胚轴黄化诱导的不定根形成，而GA合成和信号突变体显然表现出从离体叶片的DNRR减少。为了澄清这一矛盾，我们使用了GA生物合成抑制剂多效唑（PBZ），发现PBZ对拟南芥中两种类型的不定根形成都有积极作用。一致地，GA处理对两种不定根形成机制都有负面影响，而在我们的条件下，GA合成和信号的缺失促进了DNRR。我们的结果表明，PBZ处理可以挽救难生根叶片外植体（如受体突变体）中下降的不定根形成。此外，转录谱分析表明，PBZ处理改变了GA、油菜素类固醇和生长素反应，其中包括上调在不定根起始中起关键作用的基因。
