Background: Taxus is a rare gymnosperm plant that is the sole producer of the anticancer drug paclitaxel. The growth and development of Taxus is affected by environmental factors such as light. However, little is known about how light conditions affect growth and metabolic processes, especially paclitaxel biosynthesis. Results: In this study, we applied three different light conditions to Taxus chinensis young saplings and investigated the physiological response and gene expression. Our observations showed that exposure to high light led to oxidative stress, caused photoinhibition, and damaged the photosynthetic systems in T. chinensis. The paclitaxel content in T. chinensis leaves was significantly decreased after the light intensity increased. Transcriptomic analysis revealed that numerous genes involved in paclitaxel biosynthesis and phenylpropanoid metabolic pathways were downregulated under high light. We also analyzed the expression of JA signaling genes, bHLH, MYB, AP2/ERF transcription factors, and the CYP450 families that are potentially related to paclitaxel biosynthesis. We found that several CYP450s, MYB and AP2/ERF genes were induced by high light. These genes may play an important role in tolerance to excessive light or heat stress in T. chinensis. Conclusions: Our study elucidates the molecular mechanism of the effects of light conditions on the growth and development of T. chinensis and paclitaxel biosynthesis, thus facilitating the artificial regeneration of Taxus and enhancing paclitaxel production.

Background: Soil salinization is causing ecosystem degradation and crop yield reduction worldwide, and elucidation of the mechanism of salt-tolerant plants to improve crop yield is highly significant. Podocarpus macrophyllus is an ancient gymnosperm species with a unique environmental adaptation strategy that may be attributed to its lengthy evolutionary process. The present study investigated the physiological and molecular responses of P. macrophyllus plants to salt stress by analyzing its photosynthetic system and antioxidant enzyme activity. We also analyzed the differentially expressed genes (DEGs) in P. macrophyllus under salt stress using RNA sequencing and de novo transcriptome assembly. Results: Salt treatment significantly affected the photosynthetic system in P. macrophyllus seedlings, which decreased chlorophyll content, altered chloroplast ultrastructure, and reduced photosynthesis. The activities of antioxidant enzymes increased significantly following salt stress treatment. Transcriptome analysis showed that salt stress induced a large number of genes involved in multiple metabolic and biological regulation processes. The transcription levels of genes that mediate phytohormone transport or signaling were altered. K⁺ and Ca²⁺ transporter-encoding genes and the MYB transcription factor were upregulated under salt stress. However, the genes involved in cell wall biosynthesis and secondary metabolism were downregulated. Conclusion: Our research identified some important pathways and putative genes involved in salt tolerance in P. macrophyllus and provided clues for elucidating the mechanism of salt tolerance and the utilization of the salt tolerance genes of P. macrophyllus for crop improvement.

Enterobacter cloacae produces insecticidal proteins capable of causing toxicity in pests, but the insecticidal mechanisms of these proteins for insect control remain unclear. To elucidate the mechanisms, the purified insecticidal protein from E. cloacae NK was administered to Galleria mellonella larvae either by intraperitoneal injection or by feeding. The number of hemocytes, apoptosis in immune cells, and polyphenol oxidase (PO) activity of G. mellonella larvae were detected by hemocytometer, Annexin V-FITC/PI, and UV–vis spectrophotometer, respectively. With the extension of the invasion time of NK insecticidal protein, the number of hemocytes in G. mellonella larvae decreased significantly (p < 0.05), whereas the apoptosis rate of hemocytes increased. The activity of PO showed a trend of rising-peak-sharp decline and the melanization reaction was deepened simultaneously. Moreover, the phagocytosis and coating capabilities of hemocytes decreased, and the intraperitoneal injection method was more effective than the feeding method. Taking together, the insecticidal protein of E. cloacae NK inhibits and destroys the cellular immune response of G. mellonella larvae, which suggests an important role in killing the host insect.

Background/Objectives: Licorice (Glycyrrhiza glabra L.) is a highly important medicinal plant that is widely used in China owing to its active ingredients. Its main active components are flavonoids, including liquiritigenin, liquiritin and licochalcone A. The hairy roots (HRs) induced by Agrobacterium rhizogenes are a commonly used chassis in synthetic biology to enhance the production of active compounds in medicinal plants. Methods: A biosynthesis system to acquire the active ingredients of G. glabra was established using an HR culture system. It employed a transcriptome analysis to identify the change in gene expression following treatment with methyl jasmonate (MeJA). Results: After 28 days of suspension culture, the biomass of HRs increased by approximately 34.5-fold and reached 1.83 g/100 mL flask. Treatment with MeJA significantly increased the contents of liquiritigenin, liquiritin, and glabridin in the HRs. The transcriptome data indicated that MeJA activated the flavonoid biosynthetic pathway genes in the HRs, which was largely consistent with the qRT-PCR results. Furthermore, the overexpression of the GgCHS6 gene substantially increased the content of flavonoids in HRs. Conclusions: Collectively, this study established an HR system to biosynthesize the active ingredients of G. glabra using metabolic engineering and genetic engineering techniques and provides several valuable candidate genes for further functional study.