Characterization of the Glehnia littoralis Non-specific Phospholipase C Gene GlNPC3 and Its Involvement in the Salt Stress Response

Glehnia littoralis is a medicinal halophyte that inhabits sandy beaches and has high ecological and commercial value. However, the molecular mechanism of salt adaptation in G. littoralis remains largely unknown. Here, we cloned and identified a non-specific phospholipase C gene (GlNPC3) from G. littoralis, which conferred lipid-mediated signaling during the salt stress response. The expression of GlNPC3 was induced continuously by salt treatment. Overexpression of GlNPC3 in Arabidopsis thaliana increased salt tolerance compared to wild-type (WT) plants. GlNPC3-overexpressing plants had longer roots and higher fresh and dry masses under the salt treatment. The GlNPC3 expression pattern revealed that the gene was expressed in most G. littoralis tissues, particularly in roots. The subcellular localization of GlNPC3 was mainly at the plasma membrane, and partially at the tonoplast. GlNPC3 hydrolyzed common membrane phospholipids, such as phosphotidylserine (PS), phosphoethanolamine (PE), and phosphocholine (PC). In vitro enzymatic assay showed salt-induced total non-specific phospholipase C (NPC) activation in A. thaliana GlNPC3-overexpressing plants. Plant lipid profiling showed a significant change in the membrane-lipid composition of A. thaliana GlNPC3-overexpressing plants compared to WT after the salt treatment. Furthermore, downregulation of GlNPC3 expression by virus-induced gene silencing in G. littoralis reduced the expression levels of some stress-related genes, such as SnRK2, P5SC5, TPC1, and SOS1. Together, these results indicated that GlNPC3 and GlNPC3-mediated membrane lipid change played a positive role in the response of G. littoralis to a saline environment.

Influence of MAP on the Postharvest Quality of Glehnia littoralis Fr. Schmidt ex Miq.

In Korea, to prevent the extinction of Glehnia littoralis, a cultivation method to improve productivity is being studied and quality maintenance technology is required after harvest. The objective of this study was to determine the effect of MAP on the postharvest quality of G. littoralis. The control showed a weight loss rate of more than 5% after 3 days of storage and lost its marketability, whereas MAP treatment (PE or MPE) showed a weight loss rate of about 2–3% during storage for more than 30 days. In the control, MDA and electrolyte leakage increased due to chilling injury. The total chlorophyll content was low and remained constant until about 23 days of storage in the PE treatment group and 15 days in the MPE treatment group. Among the phenolic compounds, chlorogenic acid, rutin, isoquercetin, and nicotiflorin were maintained at significantly higher levels in the PE than in the MPE. In addition, bergapten showed a highly significant upward trend in the MPE, especially after 25 days of storage when the yellowing progressed. In conclusion, MAP treatment effectively maintains quality while minimizing lipid peroxidation and maintaining phenolic compounds during low-temperature storage after harvest of G. littoralis.

Quality Control of Glehniae Radix, the Root of Glehnia Littoralis Fr. Schmidt ex Miq., Along its Value Chains

Glehniae Radix (GR) is one of the major medicinal materials in China. The global demand for GR, especially in Asian countries, is constantly increasing, and the supply of wild medicinal materials falls short of the demand. Previous studies have shown that the production and processing modes of different value chains (VCs) impact the quality of medicinal materials. After 4 years of field and market research, this study includes interviews with stakeholders in the VCs, integrates different types of VCs, and further analyzes the VCs. GR characteristics were also assessed; the length and upper-middle diameter of the collected samples were measured, and the effective components of the samples were determined to rank the GR samples according to their quality. The effective components were further analyzed by the K-means clustering method. Concomitantly, the local price (the sales price of the place where the medicinal materials are produced) and market price (the sale price of medicinal materials in the market) of GR in Chifeng, Inner Mongolia, and Anguo, Hebei, were documented, and the ARIMA (Autoregressive Integrated Moving Average) method was used to predict the GR price. Ten VCs are summarized in this article. The results showed that the income of the staff at the beginning of the VC is inadequate. Regarding GR origin, Inner Mongolia GR showed higher quality than that of other areas. As a result, the price of medicinal materials is relatively high, which corresponds to the market price of the survey. The forecast results showed that the market price of GR would increase slightly in the future, which could provide reference for the selection of medicinal materials cultivation in the future. Through the study, it was found that the vertical integration in the VCs of GR could guarantee not only the benefit of the growers but also the traceability of the medicinal materials, which further guarantees the quality of the medicinal materials. However, the complex relationship between the cultivation area and the quality of the medicinal materials is not clear, which should be addressed in future research.

Improving Germination Rate of Coastal Glehnia by Cold Stratification and Pericarp Removal

The medicinal plant, coastal glehnia (Glehnia littoralis F. Schmidt ex Miq.), belongs to the Apiaceae, which is known to exhibit morpho-physiological seed dormancy (MPD). In this study, we aimed to determine the dormancy type of this plant, along with the conditions for breaking dormancy, and how to increase its germination rate for mass production. Initially, the seeds of coastal glehnia had undeveloped embryos, which gradually developed following cold (5 °C) stratification over eight weeks. The embryo to seed (E:S) ratio increased to 66.7%, confirming that the seeds had the MPD type. Coastal glehnia seeds with pericarp did not show inhibited water uptake, and the germination inhibitory chemicals were not detected. However, removal of the pericarp improved the final germination percentage, germination speed, and T50 of coastal glehnia seeds compared with those of seeds with pericarp at 20 °C, which showed the highest value compared with other temperature treatments. Thus, cold stratification at 5 °C for eight weeks and removing the pericarp of germinating seeds maintained at 20 °C is efficient ways to break dormancy and improve the germination rate for the mass production of coastal glehnia.

Physiological and biochemical characteristics of cold stratification to overcome morphophysiological dormancy in Glehnia littoralis seed

Cold stratification is commonly used for breaking morphophysiological dormancy in Glehnia littoralis seeds. However, the physiological and biochemical characteristics of dormancy release are still unclear. For our study, dormant G. littoralis seeds were subjected to cold stratification (4°C). Physiological and biochemical characteristics, including germination percentage, the activities of antioxidant enzymes and α-amylase, and soluble sugar, soluble protein, H2O2, malondialdehyde (MDA) and coumarin were determined in imbibed seeds after different stratification periods (0, 30, 60, 90 or 120 days). The morphophysiological dormancy in G. littoralis seeds was completely released by cold stratification for 120 days. The activities of catalase (CAT) and content of hydrogen peroxide (H2O2) and total soluble sugars were significantly increased, while coumarins was significantly decreased during dormancy release. Dormancy release was significantly positively correlated with CAT activity (r = 0.903) and accumulation of H2O2 (r = 0.985) and total soluble sugars (r = 0.952), and significantly negatively correlated with coumarins (r = −0.919). Thus, the increase in H2O2, soluble sugars level and CAT activity and decrease in coumarins during cold stratification might contribute to promoting dormancy release in G. littoralis seeds.