title: Reactive oxygen species and hormone signaling cascades in endophytic bacterium induced essential oil accumulation in Atractylodes lancea.
abstract: Pseudomonas fluorescens induces gibberellin and ethylene signaling via hydrogen peroxide in planta . Ethylene activates abscisic acid signaling. Hormones increase sesquiterpenoid biosynthesis gene expression and enzyme activity, inducing essential oil accumulation. Atractylodes lancea is a famous Chinese medicinal plant, whose main active components are essential oils. Wild A. lancea has become endangered due to habitat destruction and over-exploitation. Although cultivation can ensure production of the medicinal material, the essential oil content in cultivated A. lancea is significantly lower than that in the wild herb. The application of microbes as elicitors has become an effective strategy to increase essential oil accumulation in cultivated A. lancea. Our previous study identified an endophytic bacterium, Pseudomonas fluorescens ALEB7B, which can increase essential oil accumulation in A. lancea more efficiently than other endophytes; however, the underlying mechanisms remain unknown (Physiol Plantarum 153:30-42, 2015; Appl Environ Microb 82:1577-1585, 2016). This study demonstrates that P. fluorescens ALEB7B firstly induces hydrogen peroxide (H2O2) signaling in A. lancea, which then simultaneously activates gibberellin (GA) and ethylene (ET) signaling. Subsequently, ET activates abscisic acid (ABA) signaling. GA and ABA signaling increase expression of HMGR and DXR, which encode key enzymes involved in sesquiterpenoid biosynthesis, leading to increased levels of the corresponding enzymes and then an accumulation of essential oils. Specific reactive oxygen species and hormone signaling cascades induced by P. fluorescens ALEB7B may contribute to high-efficiency essential oil accumulation in A. lancea. Illustrating the regulation mechanisms underlying P. fluorescens ALEB7B-induced essential oil accumulation not only provides the theoretical basis for the inducible synthesis of terpenoids in many medicinal plants, but also further reveals the complex and diverse interactions among different plants and their endophytes.
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, Jiangsu, China.
authors.forename: Jia-Yu
authors.initials: JY
authors.lastname: Zhou
authors.affiliation: Jiangsu High Quality Rice Research and Development Center, Nanjing Branch of China National Center Rice Improvement, Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, Jiangsu, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, Jiangsu, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, Jiangsu, China.
authors.forename: Meng-Yao
authors.initials: MY
authors.lastname: Deng-Wang
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, Jiangsu, China. daichuanchao@njnu.edu.cn.
authors.forename: Chuan-Chao
authors.initials: CC
authors.lastname: Dai
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D031174:Atractylodes / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D018533:Biomass; D060406:Brassinosteroids / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism; D060026:Endophytes / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009822:Oils, Volatile / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D013729:Terpenes / Q000378:metabolism
chemical_list: D060406:Brassinosteroids; D003517:Cyclopentanes; D005030:Ethylenes; D005875:Gibberellins; D009822:Oils, Volatile; D054883:Oxylipins; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D013729:Terpenes; D009569:Nitric Oxide; C011006:jasmonic acid; D000040:Abscisic Acid; C036216:ethylene; D006861:Hydrogen Peroxide; D020156:Salicylic Acid
keywords: Essential oil; Medicinal plant; Plant hormone; Pseudomonas fluorescens; Reactive oxygen species; Signaling crosstalk