Genes related to osmoregulation and antioxidation play important roles in the response of Trollius chinensis seedlings to saline-alkali stress

Saline-alkali stress is one of the main abiotic stress factors affecting plant growth and development. Trollius chinensis is a perennial herbal medicinal plant with high values for garden application. However, its response and tolerance to saline-alkali stress is unclear. In this study, we mixed four salts (NaCl: Na₂SO₄: NaHCO₃: Na₂CO₃) with a concentration ratio of 1:9:9:1, and applied low (40 and 80 mM) and high (120 and 160 mM) saline-alkali stress to analyze osmotic regulation substances, antioxidant systems and the gene expression of T. chinensis. Along with higher saline-alkali stress, the leaf relative water content (RWC) started to decrease only from high stress, while the malondialdehyde (MDA) content in leaves decreased continuously, and the contents of proline (Pro), soluble sugar (SS) and soluble protein (SP) increased compared with control. The activities of antioxidant enzymes and the contents of non-enzymatic antioxidants were increased positively with the accumulation of superoxide anion (O₂ ^•-) and hydrogen peroxide (H₂O₂). For instance, the ascorbic acid-glutathione (AsA-GSH) cycle was enhanced in T. chinensis seedling leaves subject to saline-alkali stress. Principal Component Analysis (PCA) indicates that MDA, Pro, SS, SP, H₂O₂, O₂ ^•-, and GSH are important indexes to evaluate the response and tolerance of T. chinensis to saline-alkali stress. Through RNA-Seq, a total of 474 differentially expressed genes (DEGs) were found in plant under low saline-alkaline stress (40 mM, MSA1) vs. control. Among them, 364 genes were up-regulated and 110 genes were down-regulated. DEGs were extensively enriched in carbohydrate transport, transferase activity, zeatin biosynthesis, ABC transporters, and spliceosome. The transcription factor family MYB, BZIP, WRKY, and NAC were related to its saline-alkali tolerance. In addition, some DEGs encode key enzymes in the processes of osmoregulation and antioxidation, including betaine aldehyde dehydrogenase (BADH), inositol monophosphatase (IMP), chloroperoxidase (CPO), thioredoxin (Trx), and germin-like protein (GLPs) were found. Overall, these findings provide new insights into the physiological changes and molecular mechanism of T. chinensis to saline-alkali stress and lay a foundation for application of T. chinensis in saline-alkali environment.

[Isolation and identification of pathogen causing damping off at seedling stage of Trollius chinensis]

Trollius chinensis is a traditional Chinese medicinal material in China, the wild resource of T. chinensis are now exhausted, and commercial medicinal T. chinensis mainly depends on artificial cultivation. As one of the most severely happened diseases at the seedling period, damping off has been a serious threaten to the breeding of T. chinensis seedlings. However, no related research have been reported so far. So, the authors collected damping-off samples of T. chinensis in 2018 from seedling breeding nursery in Guyuan, Hebei province, and carried out study on taxonomic identification of the pathogen. Damping off occurs in the T. chinensis production area from mid-May to late June every year. At the beginning, brown lesions were observed on the basal stem, then the lesions circumferential expanded and constricted, and finally resulted in the fall and death of T. chinensis seedlings. Pathogenic isolate was growing rapidly on the PDA medium, well developed aerial mycelia were grey white at first, then turned brown gradually, and a great number of small dark brown sclerotia were developed in the middle and periphery of the colony. Mycelial diameter of the pathogen was about 7 to 10 μm, near right angle or acute angle branches, near branches with septa, branches and septa with constriction. After the healthy T. chinensis seedlings were inoculated by pathogenic isolate, damping-off was observed soon, and the symptom was as same as those observed in the field. Through homogenous blast, the rDNA-ITS sequence of the pathogenic isolate shown 99.49% to 99.84% homology with Rhizoctonia solani, R. solani AG-1 IC mycelium anastomosis group and Thanatephorus cucumeris, the sexual type of Rhizoctonia. Furthermore, obvious mycelial anastomosis phenomena were observed when the pathogenic isolate and R. solani AG-1 IC strain were confronting cultured. Based on the results above, the pathogenic isolate causing damping off of T. chinensis was identified as R. solani AG-1 IC mycelial anastomosis group. RESULTS:: in the present work have important significance for further research on basic biology of the pathogen and integrated control of damping off causing by it on T. chinensis.

Anti-influenza A virus mechanism of three representative compounds from Flos Trollii via TLRs signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Flos Trollii is the dried flowers of Trollius chinensis. It has been used as a traditional herbal medicine for the treatment of upper respiratory tract infection, tonsillitis and pharyngitis in China for a long history. Veratric acid, vitexin, and trolline are the representative compounds of phenolic acids, flavonoids and alkaloids in this herbal medicine. All of these three compounds show antiviral activity which is related to the efficacy of Flos Trollii.

AIM OF THE STUDY

To investigate the anti-influenza A virus mechanism of the three representative compounds from the perspective of regulating TLRs signaling pathways, so as to understand the relevant efficacy of Flos Trollii.

MATERIALS AND METHODS

Influenza A virus A/FM/1/47 (H1N1) and mouse peritoneal macrophages (RAW264.7) were used in the whole process of investigation. MTT assay was conducted to select the appropriate experimental concentrations of the three compounds on RAW264.7 cells. Western blot, RT-PCR, and ELISA assays were performed to determine the protein and mRNA expression of key factors and related inflammatory factors of TLRs signaling pathways. Griess method was employed to detect the production of NO.

RESULTS

The three representative compounds reduced the inflammatory factors including NO, IL-6, and TNF-α and enhanced the production of IFN-β through dynamically regulating the TLRs 3, 4 and 7 pathways. Veratric acid significantly down-regulated the protein expression of TLR3 and IRF3 as well as the mRNA expression of TBK1 and TRIF. Vitexin significantly down-regulated the protein expression of TBK1 and IRF3 as well as the mRNA expression of TLR3, TBK1, TRIF and IRF3 while up-regulated the protein expression of TLR4 and IKKα. Trolline significantly down-regulated the protein expression of TLR7 whereas significantly up-regulated the protein expression of TLR4, IKKα and TAK1.

CONCLUSIONS

The three representative compounds from Flos Trollii play their parts in anti-H1N1 viral effect through partially down-regulating TLRs 3 and 7 pathways and up-regulating TLR4 pathway. They counteract the inflammatory injury caused by excessive production of NO, IL-1, IL-6, and TNF-α induced by virus infection and enhance the production of IFN-β so as to eliminate the virus.

An efficient approach for the extraction of orientin and vitexin from Trollius chinensis flowers using ultrasonic circulating technique

Ultrasonic circulating extraction (UCE) approach was developed for effective extraction of orientin and vitexin from the flowers of Trollius chinensis successfully. In this study, some parameters potentially influencing the yields of orientin and vitexin were systematically investigated and optimized by Plackett-Burman and Box-Behnken design, and the optimum operational conditions obtained were 60% ethanol volume fraction, 1000r/min stirring speed, 30°C temperature, 28min ultrasonic irradiation time, 10mL/g liquid-solid ratio and 738W ultrasonic irradiation power. Satisfactory yields of orientin (6.05±0.19mg/g) and vitexin (0.96±0.03mg/g) were obtained in a relatively shorter extraction time under the derived optimum conditions, compared to other ultrasonic extraction methods and heat extraction methods. The mechanism of UCE procedure was discussed in detail, to illustrate the advantage of UCE in the extraction process. In addition, no degradation of orientin and vitexin and high reproducibility of the developed UCE method were observed under the optimum conditions. The proposed UCE technique with high-capacity and circulation function is a rapid and efficient sample extraction technique, and performs promising in large-scale sample preparation.

Absorption properties and mechanism of trolline and veratric acid and their implication to an evaluation of the effective components of the flowers of Trollius chinensis

AIM

To study the absorption properties and mechanism of two important components, trolline and veratric acid, from the flowers of Trollius chinensis, in order to better understand the contribution of these two compounds to the effectiveness of these flowers.

METHOD

The human Caco-2 cell monolayer model was employed to study the transport of trolline and veratric acid from apical side (AP) to basal side (BL), and from BL to AP by determining the transport rates as the function of time and concentration and calculating apparent permeability coefficients (Papp).

RESULTS

Trolline and veratric acid were transported across Caco-2 cell monolayer through different mechanisms in a concentration dependent manner. Trolline was transported at a Papp level of 10(-6) cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of more than 1.8 or less than 0.8, while veratric acid was transported at a Papp level of 10(-5)cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of close to 1.0.

CONCLUSION

Trolline is moderately absorbed through an associative mechanism involving active and passive transport, and veratric acid is well-absorbed mainly through passive diffusion. These factors should be taken into account when chemically assessing the pharmacodynamic material basis of the flowers of T. chinensis.

Antimicrobial constituents from the flowers of Trollius chinensis

A new 1-aryl-isochroman, trolliusol A (1), was isolated from the flowers of Trollius chinensis, along with seven known phenolic compounds in an antimicrobial activity-directed phytochemical investigation. The structures of these compounds were elucidated by spectroscopic methods, and their inhibitory activities against one fungus and four bacterial strains were measured.

Investigation on Flos Trollii: constituents and bioactivities

Flos Trollii, the flowers of Trollius chinensis Bunge, has been widely used in Chinese and Mongolian medicine for its efficacy of heat-clearing and detoxification. This drug has both medicinal and edible applications, and has led to various pharmacognosy, natural product chemistry, and pharmacology studies. As a result, its chemical constituents and bioactivities have been well-characterized in recent years. Nevertheless, a couple of critical issues, such as the major effective components, are still unresolved. The present review summarizes research progress on this drug regarding the constituents and bioactivities based on investigations in these laboratories and the results reported in recent publications. In addition, the pending issues are discussed and constructive suggestions for further investigation are proposed.

Contribution evaluation of the floral parts to orientin and vitexin concentrations in the flowers of Trollius chinensis

AIM

To provide a comprehensive procedure to evaluate the contribution of the floral parts to the yield of the major components from the flowers of Trollius chinensis, to underlay the selective breeding, cultivation, development, and utilization of the flowers.

METHODS

Five floral parts from eleven batches of the flowers of T. chinensis were examined by HPLC analysis for the content of orientin and vitexin, and by gravimetric analysis for their respective mass fraction. The contribution of each floral part was calculated using mathematical methods based on the results of the content and mass fraction. Variance analysis was carried out by Kruskal-Wallis H test and PCA method.

RESULTS

The calculated mean contributions of calyx, corolla, stamens and pistils, stalk, and ovary to the yield of both orientin and vitexin were 76.99% and 71.93%, 9.60% and 8.33%, 9.21% and 8.10%, 2.17% and 6.62%, and 2.03% and 5.02%, respectively.

CONCLUSION

The floral parts contribute unequally to the yield of orientin and vitexin, and the calyx contributes the highest and makes a significant difference compared with any other part.