Endophyte-inoculated rhizomes of Paris polyphylla improve polyphyllin biosynthesis and yield: a transcriptomic analysis of the underlying mechanism

Qing Zhang; Sheng Chang; Ying Yang; Congfang Xi; Yumei Dong; Lufeng Liu; Yunchao He; Yu Liu; Bo Cai; Tao Liu

doi:10.3389/fmicb.2023.1261140

Endophyte-inoculated rhizomes of Paris polyphylla improve polyphyllin biosynthesis and yield: a transcriptomic analysis of the underlying mechanism

Front Microbiol. 2023 Oct 30:14:1261140. doi: 10.3389/fmicb.2023.1261140. eCollection 2023.

Authors

Qing Zhang¹, Sheng Chang², Ying Yang², Congfang Xi¹, Yumei Dong¹, Lufeng Liu¹, Yunchao He³, Yu Liu⁴, Bo Cai², Tao Liu¹

Affiliations

¹ National-Local Joint Engineering Research Center on Germplasm Innovation and Utilization of Chinese Medicinal Materials in Southwest China, College of Agriculture and Biotechnology, Yunnan Agricultural University, Kunming, China.
² Center of Yunnan Zhongyan Industry Co., Ltd., Kunming, China.
³ Lushui City Katma Township People's Government Agricultural and Rural Integrated Service Center, Lushui, Yunnan, China.
⁴ Shenzhen TCM Hospital, Shenzhen, China.

Abstract

Introduction: Polyphyllin from Paris polyphylla var. yunnanensis exhibits anti-inflammatory, analgesic, antibacterial, and antiviral properties. However, the current production of polyphyllin can barely meet market demand. To improve the content of polyphyllin produced by P. polyphylla, two endophyte strains, Bacillus cereus LgD2 and Fusarium oxysporum TPB, were isolated from Paris fargesii Franch. and inoculated in the roots of P. polyphylla. Both symbiotic strains significantly promoted the accumulation of saponins in P. polyphylla.

Methods: The content of polyphyllin in rhizomes of P. polyphylla treated with TPB with LgD2 strain was determined using High Performance Liquid Chromatography and the expressed genes were analyzed by RNA-seq. Gene Ontology and Kyoto Encyclopedia of Genes annotations were performed on the differentially expressed genes, a clustering tree of UDP-glycosyltransferase (UGT) and cytochrome P450 (CYP450) gene families was constructed, and UGT and CYP450 involved in the biosynthesis of polyphyllin were predicted using weighted correlation network analysis (WGCNA).

Results: RNA-seq and qRT-PCR analyses showed that endophytic inoculation did not promote polyphyllin accumulation by enhancing the upstream terpene biosynthesis pathway, but probably by up-regulating the downstream CYP450 and UGT genes associated with polyphyllin biosynthesis. Genomes enrichment analyses of differentially expressed genes indicated that inoculation with LgD2 and TPB played a positive role in promoting the defense against pathogenic bacteria, enhancing the biosynthesis of carbohydrates, attenuating the process of nitrogen metabolism, and maintaining the equilibrium of the redox reaction homeostasis, potentially indirectly enhancing the polyphyllin yield of P. polyphylla. By combining differentially expressed genes screening, WGCNA, and phylogenetic tree analyses, 17 CYP450 and 2 UGT candidate genes involved in the biosynthesis of polyphyllin I, polyphyllin II, polyphyllin VII, polyphyllin D, and polyphyllin H were identified. These results suggest that endophytes probably effectively promote the accumulation of polyphyllin by regulating key downstream genes in biosynthetic pathways.

Discussion: This study provides a new approach for investigating the regulatory mechanisms of endophytes that promote the production and accumulation of polyphyllin in P. polyphylla, providing a basis for further elucidating the mechanisms of plant-endophyte interactions.

Keywords: Paris polyphylla; beneficial interaction; endophyte; polyphyllin biosynthesis; transcriptome.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the National Key R&D Program of China (grant no. 2021YFD1000202 and 2021YFD1601003), Key projects of Yunnan Provincial Natural Fund (grant no. 202201AS070064), Key R&D program of Yunnan Province of China (grant no. 202103AC100003), and the Research and Application of Personalized Cigarette Products (grant no. 2023CP02).