The primary mechanism of endophytic fungus Gilmaniella sp AL12 promotion of plant growth and sesquiterpenoid accumulation in Atractylodes lancea

摘要

Atractylodes lancea is a traditional Chinese herb, and its quality depends on the main active compounds sesquiterpenoids. In recent years, guaranteeing the quality and yield of A. lancea has become problematic. Our previous results have shown that the endophytic fungus AL12 (Gilmaniella sp.) promotes plant growth and sesquiterpenoid biosynthesis of A. lancea. However, little has been done to uncover the mechanism of this "double-promotion". In this study, plant biomass and sesquiterpenoid content were analyzed to verify this "double-promotion" effect of AL12 on A. lancea. Physiological tests (such as root viability, element content, rubisco content, and some phytohormones levels) were performed to try to identify the mechanism of improved plant growth. The results showed that growth promotion effect induced by AL12 on A. lancea may depend on increased nutrient content, improved photosynthesis and enhanced cytokinin signaling. Secondary metabolite biosynthesis consumes substance and energy during plant growth. Transcript analysis indicated that AL12 stimulates sesquiterpenoid biosynthesis through the MVA pathway. Physiological tests (such as sesquiterpenoid biosynthesis precursors and organic acids of tricarboxylic acid cycle) were performed to try to identify the mechanism of improved sesquiterpenoid accumulation. The results showed that AL12 improves the primary metabolism of A. lancea including photosynthesis, glycolysis, and the TCA cycle, thus providing sufficient carbon and energy for sesquiterpenoid biosynthesis. To summarize, this work uncover the primary mechanism of AL12 promotion of plant growth and sesquiterpenoid accumulation in A. lancea. This study provides a theoretical basis for obtaining higher yield and quality medicinal plants and also provides a framework to understand plant-endophyte interactions.