The regulatory mechanism of chilling-induced dormancy transition from endo-dormancy to non-dormancy in Polygonatum kingianum Coll.et Hemsl rhizome bud
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We identified three dormant stages of Polygonatum kingianum and changes that occurred during dormancy transition in the following aspects including cell wall and hormones, as well as interaction among them.
Polygonatum kingianum Coll.et Hemsl (P. kingianum) is an important traditional Chinese medicine, but the mechanism of its rhizome bud dormancy has not yet been studied systematically. In this study, three dormancy phases were induced under controlled conditions, and changes occurring during the transition were examined, focusing on phytohormones and the cell wall. As revealed by HPLC–MS (High Performance Liquid Chromatography–Mass Spectrometry) analysis, the endo- to non-dormancy transition was association with a reduced abscisic acid (ABA)/gibberellin (GA3) ratio, a decreased level of auxin (IAA) and an increased level of trans-zeatin (tZR). Transmission electron microscopy showed that plasmodesmata (PDs) and the cell wall of the bud underwent significant changes between endo- and eco-dormancy. A total of 95,462 differentially expressed genes (DEGs) were identified based on transcriptomics, and clustering and principal component analysis confirmed the different physiological statuses of the three types of bud samples. Changes in the abundance of transcripts associated with IAA, cytokinins (CTKs), GA, ABA, brassinolide (BR), jasmonic acid (JA), ethylene, salicylic acid (SA), PDs and cell wall-loosening factors were analysed during the bud dormancy transition in P. kingianum. Furthermore, nitrilase 4 (NIT4) and tryptophan synthase alpha chain (TSA1), which are related to IAA synthesis, were identified as hub genes of the co-expression network, and strong interactions between hormones and cell wall-related factors were observed. This research will provide a good model for chilling-treated rhizome bud dormancy in P. kingianum and cultivation of this plant.
KeywordsRhizome bud dormancy Polygonatum kingianum RNA-Seq Plant hormone Cell wall
I am very grateful to Ms. Liu for her help in the preparation of ultrathin sections and the RT-qPCR experiment. We also appreciate He Su for providing help about data analysis. I would like to thank Ms. Han, Mr. Yin and Ms. Hao for their assistance in the experiment. Most of all, I would like to thank professor Dong for his guidance on experimental consideration. We are particularly grateful to Liqing duojie, State Food and Drug Administration, Yunnan province for offering plantation base. We also express gratitude Yushi Zhang in College of Agronomy and Biotechnology, China Agricultural University for assistance of DEGs analysis. The funding for this work comes from Research on Seedling Breeding Technology of Paris Polyphylla granted by Chuansen Limited Company in Xishuangbanna.
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