Composition, functional, and niche differentiation of fungal communities in the rhizosphere and root endosphere of Cinnamomum migao in southwestern China.

AIMS: Roots are key parts of plant material circulation and energy flow, creating two distinct niches for the plant microbiome, such as the rhizosphere and root endosphere, which interact to maintain plant growth and health. In this study, two niches of plant rhizosphere and root endosphere were selected to study the composition and differences of fungi communities in order to better understand how differences in the structure and function of plant fungi communities affect plant health. METHODS AND RESULTS: The community structure, diversity, and ecological function of fungi in the rhizosphere and root endosphere of Cinnamomum migao were studied using high-throughput sequencing techniques, traditional culture methods, and the FUNGuild database. The results of the analysis of alpha diversity showed that the diversity of rhizosphere fungal communities in C. migao was much higher than that of root endosphere communities. Some similarities and differences were noted between the two niche fungal communities, and some fungi had niche preferences. Functional prediction results demonstrated that fungi in the rhizosphere and root endosphere adopt multiple trophic modes, mostly saprophytic fungi. CONCLUSIONS: This study provided a basis for an in-depth understanding of the structural variation, niche differentiation, and function of plant root-related fungal microbiota. We believe that it could provide guidance on the subsequent development of beneficial fungi.

Rhizobacterial compositions and their relationships with soil properties and medicinal bioactive ingredients in Cinnamomum migao.

Introduction: Rhizobacterial communities and their metabolites can affect plant growth, development, and stress resistance, as well as the biosynthesis and accumulation of bioactive compounds in medicinal plants. This relationship has been well-characterized in many medicinal herbs, although much less commonly in medicinal trees. Methods: Here, we analyzed the composition and structure of Cinnamomum migao rhizobacterial communities across nine growing regions in Yunnan, Guizhou and Guangxi, China, as well as differences in soil properties and fruit bioactive compounds. Results: Results showed that the C. migao rhizobacterial communities exhibited high species richness, but location-specific differences in structure. Site-specific differences in soil properties and bioactive compounds were also observed. Furthermore, rhizobacterial community compositions were correlated with both soil properties and fruit bioactive compounds, metabolism-related functions were most common in C. migao rhizobacteria. Discussion: Several bacterial genera, including Acidothermus, Acidibacter, Bryobacter, Candidatus_Solibacter, and Acidimicrobiales, potentially promote the biosynthesis and accumulation of 1,8-cineole, cypressene, limonene, and α-terpineol, Nitrospira and Alphaproteobacteria may play an inhibitory role. Finally, our results emphasized the critical role that soil pH and nitrogen levels play in driving rhizobacterial community structure, and specific functional bacteria can also counteract with soil properties, Acidibacter and Nitrospira can affect soil pH and nitrogen effectiveness. Overall, this study provides additional insight into the complex correlation of rhizosphere microorganisms with bioactive ingredients and soil properties of medicinal plants.

Effects of rhizosphere fungi on the chemical composition of fruits of the medicinal plant Cinnamomum migao endemic to southwestern China.

BACKGROUND: This study examined how rhizosphere fungi influence the accumulation of chemical components in fruits of a small population species of Cinnamomum migao. RESULTS: Ascomycota and Basidiomycota were dominant in the rhizosphere fungal community of C. migao. Pestalotiopsis and Gibellulopsis were associated with α-Terpineol and sabinene content, and Gibellulopsis was associated with crude fat and carbohydrate content. There were significant differences in rhizosphere fungal populations between watersheds, and there was no obvious change between fruiting periods. Gibberella, Ilyonectria, Micropsalliota, and Geminibasidium promoted sabinene accumulation, and Clitocybula promoted α-Terpineol accumulation. CONCLUSION: The climate-related differentiation of rhizosphere fungal communities in watershed areas is the main driver of the chemical composition of C. migao fruit. The control of the production of biologically active compounds by the rhizosphere fungal community provides new opportunities to increase the industrial and medicinal value of the fruit of C. migao.

Transcriptome analysis of Cinnamomum migao seed germination in medicinal plants of Southwest China.

BACKGROUND: Cinnamomum migao is an endangered evergreen woody plant species endemic to China. Its fruit is used as a traditional medicine by the Miao nationality of China and has a high commercial value. However, its seed germination rate is extremely low under natural and artificial conditions. As the foundation of plant propagation, seed germination involves a series of physiological, cellular, and molecular changes; however, the molecular events and systematic changes occurring during C. migao seed germination remain unclear. RESULTS: In this study, combined with the changes in physiological indexes and transcription levels, we revealed the regulation characteristics of cell structures, storage substances, and antioxidant capacity during seed germination. Electron microscopy analysis revealed that abundant smooth and full oil bodies were present in the cotyledons of the seeds. With seed germination, oil bodies and other substances gradually degraded to supply energy; this was consistent with the content of storage substances. In parallel to electron microscopy and physiological analyses, transcriptome analysis showed that 80-90 % of differentially expressed genes (DEGs) appeared after seed imbibition, reflecting important development and physiological changes. The unigenes involved in material metabolism (glycerolipid metabolism, fatty acid degradation, and starch and sucrose metabolism) and energy supply pathways (pentose phosphate pathway, glycolysis pathway, pyruvate metabolism, tricarboxylic acid cycle, and oxidative phosphorylation) were differentially expressed in the four germination stages. Among these DEGs, a small number of genes in the energy supply pathway at the initial stage of germination maintained high level of expression to maintain seed vigor and germination ability. Genes involved in lipid metabolism were firstly activated at a large scale in the LK (seed coat fissure) stage, and then genes involved in carbohydrates (CHO) metabolism were activated, which had their own species specificity. CONCLUSIONS: Our study revealed the transcriptional levels of genes and the sequence of their corresponding metabolic pathways during seed germination. The changes in cell structure and physiological indexes also confirmed these events. Our findings provide a foundation for determining the molecular mechanisms underlying seed germination.

Simulated atmospheric nitrogen deposition inhibited the leaf litter decomposition of Cinnamomum migao H. W. Li in Southwest China.

Atmospheric nitrogen (N) deposition could affect various ecological processes in forest ecosystems, including plant litter decomposition and nutrient cycling. However, the mechanism of underlying litter decomposition and nutrient cycling of Cinnamomum migao under N deposition remains unclear. Therefore, we conducted a simulated N deposition experiment including four onsite treatments to assess the effects of N input on C. migao leaf litter decomposition, nutrient release, and soil enzyme activity. The results showed that simulated N deposition significantly increased the amount of total residual mass and lignin and cellulose, decreased the decomposition rate, and suppressed net nutrient release. N input increased C, N, and P ratios as decomposition progressed, and the proportion of mass remaining was positively correlated with the proportions of lignin and cellulose remaining at the later stage of decomposition. The differences in soil enzyme activity were primarily due to enzyme type and sampling time. We conclude that simulated N deposition significantly suppressed the leaf litter decomposition of C. migao by mainly altering the chemical properties and suppressing the decomposition of the organic matter in leaf litter. Lignin might have played an important role in the loss of leaf litter biomass at the later stage of decomposition.