ABSTRACT
Root (rhizome) rot of Polygonatum plants has received substantial attention because it threatens yield and sustainable utilization in the polygonati rhizome industry. However, the potential pathogens that cause rhizome rot as well as the direct and indirect (via root-associated microbes) strategies by which Polygonatum defends against pathogens remain largely unknown. Herein, we used integrated multiomics of plant-targeted metabolomics and transcriptomics, microbiome, and culture-based methods to systematically investigate the interactions between the Polygonatum cyrtonema Hua root-associated microbiota and pathogens. We found that root rot inhibited P. cyrtonema rhizome growth and that the fresh weight significantly decreased (P < 0.001). The transcriptomic and metabonomic results showed that the expression of differentially expressed genes (DEGs) related to specialized metabolic and systemic resistance pathways, such as glycolysis/gluconeogenesis and flavonoid biosynthesis, cycloartenol synthase activity (related to saponin synthesis), mitogen-activated protein kinase (MAPK) signaling, and plant hormone signal transduction, was particularly increased in diseased rhizomes. Consistently, the contents of lactose, d-fructose, sarsasapogenin, asperulosidic acid, botulin, myricadoil, and other saponins, which are functional medicinal compounds present in P. cyrtonema rhizomes, were also increased in diseased plants infected with rhizome rot. The microbiome sequencing and culture results showed that root rot disrupted the P. cyrtonema bacterial and fungal communities and reduced the microbial diversity in the rhizomes and rhizosphere soil. We further found that a clear enrichment of Streptomyces violascens XTBG45 (HJB-XTBG45) in the healthy rhizosphere could control the root rot caused by Fusarium oxysporum and Colletotrichum spaethianum. Taken together, our results indicate that P. cyrtonema can modulate the plant immune system and metabolic processes and enrich beneficial root microbiota to defend against pathogens. IMPORTANCE Root (rhizome or tuber) reproduction is the main method for the agricultural cultivation of many important cash crops, and infected crop plants rot, exhibit retarded growth, and experience yield losses. While many studies have investigated medicinal plants and their functional medicinal compounds, the occurrence of root (rhizome) rot of plant and soil microbiota has received little attention. Therefore, we used integrated multiomics and culture-based methods to systematically study rhizome rot on the famous Chinese medicine Polygonatum cyrtonema and identify pathogens and beneficial microbiota of rhizome rot. Rhizome rot disrupted the Polygonatum-associated microbiota and reduced microbial diversity, and rhizome transcription and metabolic processes significantly changed. Our work provides evidence that rhizome rot not only changes rhizome transcription and functional metabolite contents but also impacts the microbial community diversity, assembly, and function of the rhizome and rhizosphere. This study provides a new friendly strategy for medicinal plant breeding and agricultural utilization.
Subject(s)
Polygonatum , Rhizome , Rhizosphere , Soil , TranscriptomeABSTRACT
BACKGROUND: The Wuliang Mountains of the Jingdong region is a settlement area of the Yi community located in south-western Yunnan Province in China. Due to its unique geographical location, this area harbours abundant medicinal plant resources. The medicinal plants used by the local people have a long history and play an important role in their daily life. During the long-term mixed lifestyle, the knowledge of traditional medicinal plants in different communities has been assimilated to some extent. Therefore, this paper is based on ethnobotanical investigations to document traditional medicinal plants used by local people and discuss the differences between the Yi and Han communities in the study area. METHODS: Data on traditional medicinal plants were collected from September 2016 to August 2017 in the Yi autonomous county of Jingdong. Seven townships and 16 villages were selected for the field investigations. Information was obtained through key informant interviews. A total of 44 key informants were interviewed, and all of them were herbalists or herbal sellers. RESULTS: In this study, a total of 302 traditional medicinal plant species belonging to 117 families and 252 genera were investigated and documented, most of which were obtained from herbalists. Although family Asteraceae was the most prevalent, with 27 species, the most commonly utilized species were members of family Papaveraceae, Dactylicapnos scandens (D. Don) Hutch., which is used as an antipyretic drug. Herbs comprised half of the total number of species, and the whole plant is the most frequently utilized plant part. The plants were used to treat more than 93 human diseases, with antipyretic drugs being the most common form of herbal medicine. The traditional medicinal plants used in the study area possess a high ratio of being documented in the literature. According to the analysis, the Chinese Pharmacopoeia recorded 76 species and the Resources of Traditional Chinese Medicine recorded 233 species of traditional medicinal plants. By evaluating the endangered status of the traditional medicinal plants in the study area, we found good conservation status of the cited medicinal plants. Regarding the similarity between the communities, there were significant differences between the Yi and Han communities, as indicated by the Jaccard similarity index (0.232). CONCLUSIONS: Medicinal plants are the embodiment of wisdom from our ancestors and play a significant role in treating various human disorders. As one of the birthplaces of Yi medicine, the study area possesses a high species diversity of traditional medicinal plants used by local people. With the rapid development of modern medicine, however, the inheritance of this valuable culture is facing enormous threats even though its potential value has not yet been fully explored. Therefore, some effective protection measures should be taken, and some modern techniques should be implemented to prove the safety and improve the scientific acceptance of the traditional medicinal plants.