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.

Comparative Transcriptomics and Proteomics of Atractylodes lancea in Response to Endophytic Fungus Gilmaniella sp. AL12 Reveals Regulation in Plant Metabolism

“…Its bioactive component, the sesquiterpenoids, possesses various pharmacology properties such as antibacterial, antitumour, and immunomodulation abilities (Wang et al, 2008; Koonrungsesomboon et al, 2014; Na-Bangchang et al, 2017). Over the past few years, natural sources of A. lancea have been in short supply because of the excessive exploitation and slow growth rate of the herb (Zhou et al, 2016). The medicinal source of A. lancea mainly derives from artificial cultivation, but the yield and quality of this herb are relatively low (Zhou et al, 2016).…”

“…Over the past few years, natural sources of A. lancea have been in short supply because of the excessive exploitation and slow growth rate of the herb (Zhou et al, 2016). The medicinal source of A. lancea mainly derives from artificial cultivation, but the yield and quality of this herb are relatively low (Zhou et al, 2016). At present, it is urgent to improve the quality and quantity of the herb as the market demand for A. lancea is increasing on a daily basis.…”

Influence of tissue and geographic locality on culturable endophytic bacteria of Atractylodes macrocephala

“…In Salvia miltiorrhiza hairy roots, Pseudomonas significantly improved tanshinone content via the improved activity of enzymes involved in the tanshinone biosynthetic pathway [8]. Pseudomonas fluorescens increased essential oil accumulation in Atractylodes lancea by increasing the activity of enzymes involved in sesquiterpenoid biosynthesis [38]. Thus, our results indicate several endophytic bacteria’s role in the metabolism of sesquiterpenoids.…”

Medicinal Plants and Their Bacterial Microbiota: A Review on Antimicrobial Compounds Production for Plant and Human Health

“…In other cases, the inoculation of bacterial endophytes, previously isolated by the roots of W. somnifera, has increased the withanolide content in plant tissue during Alternaria alternata pathogenicity and upregulated the genes involved in withanolide biosynthetic pathways in both leaves and roots [54,59]. In another case, the bacterial endophytic P. fluorescens strain was able to enhance the accumulation of EOs in Atractylodes lancea through molecular signaling involving hydrogen peroxide, gibberellin, ethylene, and abscisic acid [60]. The same authors have also demonstrated that this strain of P. fluorescens induces a high production of medicinal sesquiterpenoid in A. lancea [61].…”