Bacillus cereus Enhanced Medicinal Ingredient Biosynthesis in Glycyrrhiza uralensis Fisch. Under Different Conditions Based on the Transcriptome and Polymerase Chain Reaction Analysis

Abstract

The aim of this study was to evaluate the effect of Bacillus cereus (B. cereus) on the seedling growth and accumulation of medicinal ingredients of Glycyrrhiza uralensis Fisch. (G. uralensis) under control and salt stress conditions. Our results revealed the different effects of B. cereus on the seedling growth and accumulation of medicinal ingredients particularly in different conditions based on the transcriptome and polymerase chain reaction (PCR) analysis. Under the control condition, B. cereus significantly increased the expression level of the β-AS, SQS, CHS, LUS, UGAT, CYP72A154, and CYP88D6 genes and liquiritigenin content. Under salt stress, B. cereus significantly increased root length and lateral root number of G. uralensis seedlings, the expression level of HMGR, β-AS, CHS, LUS, UGAT, CYP72A154, CYP88D6, and SE genes, and the contents of glycyrrhizic acid and glycyrrhetinic acid. Notably, the effect of B. cereus on the seedling growth and the medicinal ingredient biosynthesis was different under control and salt stress conditions. Specifically, the effect of B. cereus on the seedling growth under salt stress was greater than that under the control condition. Moreover, B. cereus increased liquiritigenin content under the control condition, which is closely related to flavone and flavonol biosynthesis, while it increased the contents of glycyrrhizic acid and glycyrrhetinic acid under salt stress, which is closely related to phenylpropanoid biosynthesis, and the MVA pathway is also involved. All in all, endophytes B. cereus could be used as a sustainable tool to develop effective bioinoculants to enhance the contents of medicinal ingredients in G. uralensis.