Panax notoginseng Root Cell Death Caused by the Autotoxic Ginsenoside Rg1 Is Due to Over-Accumulation of ROS, as Revealed by Transcriptomic and Cellular Approaches

Min Yang; Youcong Chuan; Cunwu Guo; Jingjing Liao; Yanguo Xu; Xinyue Mei; Yixiang Liu; Huichuan Huang; Xiahong He; Shusheng Zhu

doi:10.3389/fpls.2018.00264

Panax notoginseng Root Cell Death Caused by the Autotoxic Ginsenoside Rg₁ Is Due to Over-Accumulation of ROS, as Revealed by Transcriptomic and Cellular Approaches

Front Plant Sci. 2018 Feb 28:9:264. doi: 10.3389/fpls.2018.00264. eCollection 2018.

Authors

Min Yang^{1

2}, Youcong Chuan^{1

2}, Cunwu Guo^{1

2}, Jingjing Liao^{1

2}, Yanguo Xu^{1

2}, Xinyue Mei², Yixiang Liu^{1

2}, Huichuan Huang^{1

2}, Xiahong He^{1

2}, Shusheng Zhu^{1

2}

Affiliations

¹ State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China.
² Key Laboratory for Agro-biodiversity and Pest Control of the Ministry of Education, Yunnan Agricultural University, Kunming, China.

Abstract

Panax notoginseng is a highly valuable medicinal herb, but its culture is strongly hindered by replant failure, mainly due to autotoxicity. Deciphering the response mechanisms of plants to autotoxins is critical for overcoming the observed autotoxicity. Here, we elucidated the response of P. notoginseng to the autotoxic ginsenoside Rg₁ via transcriptomic and cellular approaches. Cellular analyses demonstrated that Rg₁ inhibited root growth by disrupting the cell membrane and wall. Transcriptomic analyses confirmed that genes related to the cell membrane, cell wall decomposition and reactive oxygen species (ROS) metabolism were up-regulated by Rg₁ stress. Further cellular analyses revealed that Rg₁ induced ROS ([Formula: see text] and H₂O₂) accumulation in root cells by suppressing ascorbate peroxidase (APX) and the activities of enzymes involved in the ascorbate-glutathione (ASC-GSH) cycle. Exogenous antioxidants (ASC and gentiobiose) helped cells scavenge over-accumulated ROS by promoting superoxide dismutase (SOD) activity and the ASC-GSH cycle. Collectively, the autotoxin Rg₁ caused root cell death by inducing the over-accumulation of ROS, and the use of exogenous antioxidants could represent a strategy for overcoming autotoxicity.

Keywords: Panax notoginseng; antioxidant; autotoxicity; cell wall; ginsenosides; reactive oxygen species; transcriptomics.