Relatively high light inhibits reserves degradation in the Coptis chinensis rhizome during the leaf expansion by changing the source-sink relationship.

The early spring is a seasonal high-light "window" for new leaf growth and photosynthetic carbon capture by the shade-tolerant evergreen understory plants. However, it remains unclear how light regulates the source-sink relationship between rhizome (RO), mature leaf (ML), and immature leaf (IL) during Coptis chinensis leaf expansion. Understanding this relationship is essential to reducing RO reserve degradation and ultimately promote RO biomass accumulation. The plants grew in an artificial climate chamber with low (50 µmol m-2 s-1) and relatively high (200 µmol m-2 s-1) light intensity treatments. Leaf fluorescence, foliar phosphorus (P) fractions, soluble sugars, starch, total P, and alkaloid concentrations in ILs, MLs, and RO were measured, and 13C labeling was used to indicate the direction of photosynthetic carbon flow between organs. The plants grown under high light intensity had higher levels of starch in RO and higher RO biomass at the end of the year compared to those grown under low light intensity. The photosystem II (PSII) operating efficiency [Y(II)], relative electron transport rate (rETR), and photochemical quenching (qP), as well as sucrose and glucose, in ILs and MLs under relatively high light, was higher than those under low light. The glucose and starch concentrations in ILs at 35 d was significantly higher than that at 15 d when plants were under 200 µmol m-2 s-1, while they were not significantly changed and remained low at 50 µmol m-2 s-1. The 13C was detected in the RO when plants were grown at 200 µmol m-2 s-1, regardless of ILs and MLs 13C labeling, while no 13C was detected in the RO when plants were under 50 µmol m-2 s-1. Additionally, the proportion of photosynthetic transport from ILs to MLs was significantly higher than that from MLs to ILs under the 50-µmol m-2 s-1 limit. Total P concentration in ILs was lower under relatively high light, but there was no difference in nucleic acid P concentration in ILs under the two light intensity treatments. The alkaloid concentration in RO was lower under 200 µmol m-2 s-1 than that under 50 µmol m-2 s-1. We propose that relatively high light reduces the need for carbohydrates and P stored in the RO to support IL growth by (1) accelerating the sink-to-source transition in ILs, which inhibits the use of reserves in the RO; (2) using energy from MLs to support IL growth, thereby reducing RO reserve consumption, and (3) reducing the demand for P by investing less in the development of photosynthetic machinery. Furthermore, under low light, MLs serve as a sink and rely on other organs for support, directly or indirectly exacerbating the reserves lost in the RO.

Comprehensive analysis of the complete mitochondrial genomes of three Coptis species (C. chinensis, C. deltoidea and C. omeiensis): the important medicinal plants in China.

Coptis plants (Ranunculaceae) contain high levels of isoquinoline alkaloids and have a long history of medicinal use. Coptis species are of great value in pharmaceutical industries and scientific research. Mitochondria are considered as one of the central units for receiving stress signals and arranging immediate responses. Comprehensive characterizations of plant mitogenomes are imperative for revealing the relationship between mitochondria, elucidating biological functions of mitochondria and understanding the environmental adaptation mechanisms of plants. Here, the mitochondrial genomes of C. chinensis, C. deltoidea and C. omeiensis were assembled through the Nanopore and Illumina sequencing platform for the first time. The genome organization, gene number, RNA editing sites, repeat sequences, gene migration from chloroplast to mitochondria were compared. The mitogenomes of C. chinensis, C. deltoidea and C. omeiensis have six, two, two circular-mapping molecules with the total length of 1,425,403 bp, 1,520,338 bp and 1,152,812 bp, respectively. The complete mitogenomes harbors 68-86 predicted functional genes including 39-51 PCGs, 26-35 tRNAs and 2-5 rRNAs. C. deltoidea mitogenome host the most abundant repeat sequences, while C. chinensis mitogenome has the largest number of transferred fragments from its chloroplasts. The large repeat sequences and foreign sequences in the mitochondrial genomes of Coptis species were related to substantial rearrangements, changes in relative position of genes and multiple copy genes. Further comparative analysis illustrated that the PCGs under selected pressure in mitochondrial genomes of the three Coptis species mainly belong to the mitochondrial complex I (NADH dehydrogenase). Heat stress adversely affected the mitochondrial complex I and V, antioxidant enzyme system, ROS accumulation and ATP production of the three Coptis species. The activation of antioxidant enzymes, increase of T-AOC and maintenance of low ROS accumulation in C. chinensis under heat stress were suggested as the factors for its thermal acclimation and normal growth at lower altitudes. This study provides comprehensive information on the Coptis mitogenomes and is of great importance to elucidate the mitochondrial functions, understand the different thermal acclimation mechanisms of Coptis plants, and breed heat-tolerant varieties.

Auxiliary rapid identification of pathogenic and antagonistic microorganisms associated with Coptis chinensis root rot by high-throughput sequencing.

Root rot reduces the yield and medical quality of C. chinensis (Cc). Previous studies of Coptis root rot focused on the identification of pathogens and the rhizosphere microbial community composition. The present study aimed to identify potential pathogenic and antagonistic microorganisms associated with root rot based on a high-throughput sequencing technique to prevent this disease. Healthy and diseased Cc in the endosphere and rhizosphere from the same field were collected to investigate the differences in microbiome composition and function. The results showed that the composition and function of microbes were different. The numbers of animal pathogens, soil saprotrophs, plant saprotrophs, and wood saprotrophs in the endosphere of diseased Cc were higher than those in the healthy endosphere and were dominated by Phaeosphaeriaceae, Cladorrhinum, Fusarium, Exophiala, and Melanommataceae. Fusarium, Volutella, Cladorrhinum, Cylindrocarpon, and Exophiala were significantly enriched in the endosphere of the diseased plants. Co-occurrence network analysis showed that Bacillus was negatively correlated with Fusarium, Volutella, and Cylindrocarpon, indicating that Bacillus may be antagonistic microorganisms. To verify the sequencing results, F. solani and F. avenaceum were isolated and verified as pathogens, and 14 Bacillus strains were isolated, which displayed an apparent suppression effect against the two pathogens on PDA medium and detached roots. The strategy of high-throughput sequencing has the potential for the comprehensive identification of pathogenic and antagonistic microorganisms for plant disease. These results provide research ideas and microbial resources for future studies on mitigating or preventing root rot damage to Cc.

Integrated metabolomics and ligand fishing approaches to screen the hypoglycemic ingredients from four Coptis medicines.

Rhizoma Coptidis, which is mainly originated from the rhizomes of Coptis chinensis, C. deltoidea, C. omeiensis and C. teeta, has been proved to possess a superior anti-diabetic effect in clinic. However, the metabolic characterization and the hypoglycemic ingredients among these Coptis species remain unclear. In this study, we employed an integrated strategy to screen the bioactive ingredients based on metabolomics and ligand fishing approaches. First, the ultra high-performance liquid chromatography coupled to quadruple time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) was used for qualitative identification of four Coptis rhizomes. After prescreening by α-glucosidase inhibition assay, an affinity ultrafiltration system was constructed to fish out hypoglycemic ingredients from the fractions with superior activity, and verified by molecular docking on a virtual platform. The distribution of major compounds suggested the four Coptis rhizomes possess similar metabolic profiles, mainly including alkaloids and phenylpropanoids. Besides, eight compounds (magnoflorine, groenlandicine, jatrorrhizine, epiberberine, columbamine, coptisine, palmatine and berberine) from the n-butanol fraction were specifically bound to α-glucosidase, and considered as hypoglycemic ingredients of Rhizoma Coptidis. Molecular docking revealed that the inhibitors bound to α-glucosidase mainly by hydrophobic interaction, hydrogen bond interaction and π-π interaction. Summary, this research leads a more systematic and comprehensive study on metabolic characterization and hypoglycemic ingredients of Rhizoma Coptidis, which can provide a theoretical basis for the further clinical application.