The Ginkgo biloba microRNA160-ERF4 module participates in terpene trilactone biosynthesis

Terpene trilactones (TTLs) are important secondary metabolites in ginkgo (Ginkgo biloba); however, their biosynthesis gene regulatory network remains unclear. Here, we isolated a G. biloba ethylene response factor 4 (GbERF4) involved in TTL synthesis. Overexpression of GbERF4 in tobacco (Nicotiana tabacum) significantly increased terpenoid content and upregulated the expression of key enzyme genes (3-hydroxy-3-methylglutaryl-CoA reductase [HMGR], 3-hydroxy-3-methylglutaryl-CoA synthase [HMGS], 1-deoxy-D-xylulose-5-phosphate reductoisomerase [DXR], 1-deoxy-D-xylulose-5-phosphate synthase [DXS], acetyl-CoA C-acetyltransferase [AACT], and geranylgeranyl diphosphate synthase [GGPPS]) in the terpenoid pathway in tobacco, suggesting that GbERF4 functions in regulating the synthesis of terpenoids. The expression pattern analysis and previous microRNA (miRNA) sequencing showed that gb-miR160 negatively regulates the biosynthesis of TTLs. Transgenic experiments showed that overexpression of gb-miR160 could significantly inhibit the accumulation of terpenoids in tobacco. Targeted inhibition and dual-luciferase reporter assays confirmed that gb-miR160 targets and negatively regulates GbERF4. Transient overexpression of GbERF4 increased TTL content in G. biloba, and further transcriptome analysis revealed that DXS, HMGS, CYPs, and transcription factor genes were upregulated. In addition, yeast 1-hybrid and dual-luciferase reporter assays showed that GbERF4 could bind to the promoters of the HMGS1, AACT1, DXS1, levopimaradiene synthase (LPS2), and GGPPS2 genes in the TTL biosynthesis pathway and activate their expression. In summary, this study investigated the molecular mechanism of the gb-miR160-GbERF4 regulatory module in regulating the biosynthesis of TTLs. It provides information for enriching the understanding of the regulatory network of TTL biosynthesis and offers important gene resources for the genetic improvement of G. biloba with high contents of TTLs.

Comprehensive analysis of JAZ family members in Ginkgo biloba reveals the regulatory role of the GbCOI1/GbJAZs/GbMYC2 module in ginkgolide biosynthesis

Ginkgo biloba L., an ancient relict plant known as a 'living fossil', has a high medicinal and nutritional value in its kernels and leaves. Ginkgolides are unique diterpene lactone compounds in G. biloba, with favorable therapeutic effects on cardiovascular and cerebrovascular diseases. Thus, it is essential to study the biosynthesis and regulatory mechanism of ginkgolide, which will contribute to quality improvement and medication requirements. In this study, the regulatory roles of the JAZ gene family and GbCOI1/GbJAZs/GbMYC2 module in ginkgolide biosynthesis were explored based on genome and methyl jasmonate-induced transcriptome. Firstly, 18 JAZ proteins were identified from G. biloba, and the gene characteristics and expansion patterns along with evolutionary relationships of these GbJAZs were analyzed systematically. Expression patterns analysis indicated that most GbJAZs expressed highly in the fibrous root and were induced significantly by methyl jasmonate. Mechanistically, yeast two-hybrid assays suggested that GbJAZ3/11 interacted with both GbMYC2 and GbCOI1, and several GbJAZ proteins could form homodimers or heterodimers between the GbJAZ family. Moreover, GbMYC2 is directly bound to the G-box element in the promoter of GbLPS, to regulate the biosynthesis of ginkgolide. Collectively, these results systematically characterized the JAZ gene family in G. biloba and demonstrated that the GbCOI1/GbJAZs/GbMYC2 module could regulate ginkgolides biosynthesis, which provides a novel insight for studying the mechanism of JA regulating ginkgolide biosynthesis.

Expression profiling of the phenylalanine ammonia-lyase (PAL) gene family in ginkgo biloba L

The PAL gene family plays an important role in plant growth, development, and response to abiotic stresses and has been identified in a variety of plants. However, a systematic characterization is still lacking in Ginkgo biloba. Using a bioinformatics approach, 11 GbPAL members of the PAL gene family identified in ginkgo were identified in this study. The protein structure and physicochemical properties indicated that the GbPAL genes were highly similar. Based on their exon-intron structures, they can be classified into three groups. A total of 62 cis-elements for hormone, light, and abiotic stress responses were identified in the promoters of GbPAL genes, indicating that PAL is a multifunctional gene family. GbPAL genes were specifically expressed in different tissues and ploidy of ginkgo. These results provide a theoretical basis for further studies on the functional expression of the GbPAL genes.

Inferring the Regulatory Network of miRNAs on Terpene Trilactone Biosynthesis Affected by Environmental Conditions

As a medicinal tree species, ginkgo (Ginkgo biloba L.) and terpene trilactones (TTLs) extracted from its leaves are the main pharmacologic activity constituents and important economic indicators of its value. The accumulation of TTLs is known to be affected by environmental stress, while the regulatory mechanism of environmental response mediated by microRNAs (miRNAs) at the post-transcriptional levels remains unclear. Here, we focused on grafted ginkgo grown in northwestern, southwestern, and eastern-central China and integrally analyzed RNA-seq and small RNA-seq high-throughput sequencing data as well as metabolomics data from leaf samples of ginkgo clones grown in natural environments. The content of bilobalide was highest among detected TTLs, and there was more than a twofold variation in the accumulation of bilobalide between growth conditions. Meanwhile, transcriptome analysis found significant differences in the expression of 19 TTL-related genes among ginkgo leaves from different environments. Small RNA sequencing and analysis showed that 62 of the 521 miRNAs identified were differentially expressed among different samples, especially the expression of miRN50, miR169h/i, and miR169e was susceptible to environmental changes. Further, we found that transcription factors (ERF, MYB, C3H, HD-ZIP, HSF, and NAC) and miRNAs (miR319e/f, miRN2, miRN54, miR157, miR185, and miRN188) could activate or inhibit the expression of TTL-related genes to participate in the regulation of terpene trilactones biosynthesis in ginkgo leaves by weighted gene co-regulatory network analysis. Our findings provide new insights into the understanding of the regulatory mechanism of TTL biosynthesis but also lay the foundation for ginkgo leaves' medicinal value improvement under global change.

Ginkgo biloba GbbZIP08 transcription factor is involved in the regulation of flavonoid biosynthesis

Ginkgo biloba is the oldest relict plant on Earth and an economic plant resource derived from China. Flavonoids extracted from G. biloba are beneficial to the prevention and treatment of cardiovascular and cerebrovascular diseases. Basic leucine zipper (bZIP) transcription factors (TFs) have been recognized to play important roles in plant secondary metabolism. In this study, GbbZIP08 was isolated and characterized. It encodes a protein containing 154 amino acids, which belongs to hypocotyl 5 in group H of the bZIP family. Tobacco transient expression assay indicated that GbbZIP08 was localized in the plant nucleus. GbbZIP08 overexpression showed that the contents of total flavonoids, kaempferol, and anthocyanin in transgenic tobacco were significantly higher than those in the wild type. Transcriptome sequencing analysis revealed significant upregulation of structural genes in the flavonoid biosynthesis pathway. In addition, phytohormone signal transduction pathways, such as the abscisic acid, salicylic acid, auxin, and jasmonic acid pathways, were enriched with a large number of differentially expressed genes. TFs such as MYB, AP2, WRKY, NAC, bZIP, and bHLH, were also differentially expressed. The above results indicated that GbbZIP08 overexpression promoted flavonoid accumulation and increased the transcription levels of flavonoid-synthesis-related genes in plants.

Site-Directed Mutation of Salicylate Decarboxylase Gene and Mechanism of Ginkgo Acid Decarboxylation

Ginkgo seed is an important Chinese medicine and food resource in China, but the toxicity of ginkgo acid in it limits its application. Previous studies have found that salicylic acid decarboxylase (Sdc) has a decarboxylation degradation effect on ginkgo acid. In order to improve the decarboxylation ability of Sdc to Ginkgo acid, 11 residues of the Sdc around the substrate (salicylic acid) were determined as mutation targets according to the analysis of crystal structure of Sdc (PDB ID:6JQX), from Trichosporon moniliiforme WU-0401, and a total of 30 single point mutant enzymes and one compound mutant enzyme were obtained. With Ginkgo acid C15:1 as the substrate, it was found from activity assay that Sdc-Y64T and Sdc-P191A had higher decarboxylation activity, which increased by 105.18% and 116.74% compared with that of wild type Sdc, respectively. The optimal pH for Sdc Y64T and Sdc-P191A to decarboxylate Ginkgo acid C15:1 was 5.5, which is the same as the wild type Sdc. The optimal temperature of Sdc-P191A was 50 °C, which was consistent with that of the wild type Sdc, but the optimal temperature of the mutant Sdc-Y64T was 40 °C, which was 10 °C lower than that of wild type Sdc.

Genome-wide identification and expression analysis of NAC family genes in Ginkgo biloba L

NAC (NAM, ATAF, CUC2) transcription factors constitute one of the largest families of plant-specific transcription factors with important roles in plant growth and development and in biotic and abiotic stresses. The physicochemical properties, gene structure, cis-acting elements and expression patterns of NAC transcription factors in Ginkgo biloba were analysed using bioinformatics, and expression of this gene family was analysed via quantitative reverse transcription PCR. The family of G. biloba NAC transcription factors had 50 members, distributed on 12 chromosomes and divided into 11 groups. Members in the same group share a similar gene structure and motif distribution. Transcriptome data analysis of G. biloba showed that 35 genes were expressed in eight tissues. Correlation analysis suggested that GbNAC007 and GNAC008 might be involved in flavonoid biosynthesis. Expression levels of 12 GbNACs under cold, het, and salt stresses were analysed. Results indicate that NAC transcription factors play an important role in response to abiotic stresses. This study provides a reference for the functional analysis of the G. biloba family of NAC transcription factors, as well as a resource for studies on the involvement of this family in responses to abiotic stresses and flavonoid biosynthesis.

Effects of dietary Ginkgo biloba leaf extract on growth performance, immunity and environmental stress tolerance of Penaeus vannamei

Ginkgo biloba leaf extract (GBE) has been extensively used in the treatment of diseases due to its anti-inflammatory, antioxidant, and immunomodulatory effects. In aquaculture, GBE is widely used as a feed additive, which is important to enhance the immunity of aquatic animals. The current study evaluated the effects of adding GBE to the diet of Penaeus vannamei (P. vannamei) under intensive aquaculture. The GBE0 (control group), GBE1, GBE2, and GBE4 groups were fed a commercial feed supplemented with 0.0, 1.0, 2.0, and 4.0 g/kg GBE for 21 days, respectively. The results showed that dietary GBE could alleviate hepatopancreas tissue damage and improve the survival rate of shrimp, and dietary 2 g/kg GBE could significantly increase the total hemocyte count (THC), the hemocyanin content, the antioxidant gene's expression, and the activity of their encoded enzymes in P. vannamei. Furthermore, transcriptome data revealed that immunity-related genes were upregulated in the GBE2 group compared with the GBE0 group after 21 days of culture. Drug metabolism-cytochrome P450, sphingolipid metabolism, linoleic acid metabolism, glycerolipid metabolism, fat digestion and protein digestion and absorption pathways were significantly enriched, according to KEGG results. Surprisingly, all of the above KEGG-enriched pathways were significantly upregulated. These findings demonstrated that supplementing P. vannamei with 2 g/kg GBE improved its environmental adaptability by improving immunity, lipid metabolism, and detoxification. In this study, a comprehensive evaluation of the effects of dietary GBE on the intensive aquaculture of P. vannamei was conducted to provide a reference for the healthy culture of P. vannamei.

Genome-wide identification and expression pattern analysis of the TCP transcription factor family in Ginkgo biloba

Plant-specific TCP transcription factors play an essential role in plant growth and development. They can regulate leaf curvature, flower symmetry and the synthesis of secondary metabolites. The flavonoids in Ginkgo biloba leaf are one of the main medicinally bioactivate compounds, which have pharmacological and beneficial health effects for humans. In this study, a total of 13 TCP genes were identified in G. biloba, and 5 of them belonged to PCF subclades (GbTCP03, GbTCP07, GbTCP05, GbTCP13, GbTCP02) while others belonged to CIN (GbTCP01, GbTCP04, GbTCP06, GbTCP08, GbTCP09, GbTCP10, GbTCP11, GbTCP12) subclades according to phylogenetic analysis. Numerous cis-acting elements related to various biotic and abiotic signals were predicted on the promoters by cis-element analysis, suggesting that the expression of GbTCPs might be co-regulated by multiple signals. Transcript abundance analysis exhibited that most of GbTCPs responded to multiple phytohormones. Among them, the relative expression levels of GbTCP06, GbTCP11, and GbTCP13 were found to be significantly influenced by exogenous ABA, SA and MeJA application. In addition, a total of 126 miRNAs were predicted to target 9 TCPs (including GbTCP01, GbTCP02, GbTCP04, GbTCP05, GbTCP06, GbTCP08, GbTCP11, GbTCP12, GbTCP13). The correlation analysis between the expression level of GbTCPs and the flavonoid contents showed that GbTCP03, GbTCP04, GbTCP07 might involve in flavonoid biosynthesis in G. biloba. In short, this study mainly provided a theoretical foundation for better understanding the potential function of TCPs in G. biloba.

Time-Series-Dependent Global Data Filtering Strategy for Mining and Profiling of Xenobiotic Metabolites in a Dynamic Complex Matrix: Application to Biotransformation of Flavonoids in the Extract of Ginkgo biloba by Gut Microbiota

Efficient characterization of xenobiotic metabolites and their dynamics in a changing complex matrix remains difficult. Herein, we proposed a time-series-dependent global data filtering strategy for the rapid and comprehensive characterization of xenobiotic metabolites and their dynamic variation based on metabolome data. A set of data preprocessing methods was used to screen potential xenobiotic metabolites, considering the differences between the treated and control groups and the fluctuations over time. To further identify metabolites of the target, an in-house accurate mass database was constructed by potential metabolic pathways and applied. Taking the extract of Ginkgo biloba (EGB) co-incubated with gut microbiota as an example, 107 compounds were identified as flavonoid-derived metabolites (including 67 original from EGB and 40 new) from 7468 ions. Their temporal metabolic profiles and regularities were also investigated. This study provided a systematic and feasible method to elucidate and profile xenobiotic metabolism.

Antiskin Aging Effects of Indole Alkaloid N-Glycoside from Ginkgo Fruit (Ginkgo biloba fruit) on TNF-α-Exposed Human Dermal Fibroblasts

Human skin aging has internal and external factors, both of which are characterized by TNF-α overproduction. Therefore, we aimed to identify a natural product that suppresses the damage that occurs in cutaneous dermal fibroblasts exposed to TNF-α. The protective effects of the indole alkaloid N-glycoside, ginkgoside B dimethyl ester (GBDE), isolated from ginkgo fruit (Ginkgo biloba fruit) were evaluated in TNF-α stimulated human dermal fibroblasts (HDFs). GBDE inhibited TNF-α-induced MMP-1 expression to 2.2 ± 0.1-fold (p < 0.01) and reversed the decrease in collagen levels to 0.4 ± 0.00-fold (p < 0.01) at 50 μM. The effect of GBDE was due to the suppression of the phospolylaton of MAPKs (ERK, 0.47 ± 0.05; JNK, 1.21 ± 0.07; p38, 0.77 ± 0.07-folds, p < 0.001) and Akt (0.14 ± 0.03-fold, p < 0.001) compared to the TNF-α group. GBDE also reduced the expression of COX-2 to 2.06 ± 0.12-fold (p < 0.001) and increased the expression of HO-1 to 10.64 ± 0.2-fold (p < 0.001). In addition, GBDE inhibited the expression of the pro-inflammatory cytokines (IL-8, 2.2 ± 0.0; IL-1β, 1.6 ± 0.0; IL-6, 2.0 ± 0.10-folds, p < 0.05). These results provide experimental evidence that GBDE can protect against skin damage, including aging.

Genome-wide transcriptome analysis reveals the regulatory network governing terpene trilactones biosynthesis in Ginkgo biloba

Ginkgo biloba L. is currently the only remaining gymnosperm of the Ginkgoaceae Ginkgo genus, and its history can be traced back to the Carboniferous 200 million years ago. Terpene trilactones (TTLs) are one of the main active ingredients in G. biloba, including ginkgolides and bilobalide. They have a good curative effect on cardiovascular and cerebrovascular diseases because of their special antagonistic effect on platelet-activating factors. Therefore, it is necessary to deeply mine genes related to TTLs and to analyze their transcriptional regulation mechanism, which will hold vitally important scientific and practical significance for quality improvement and regulation of G. biloba. In this study, we performed RNA-Seq on the root, stem, immature leaf, mature leaf, microstrobilus, ovulate strobilus, immature fruit and mature fruit of G. biloba. The TTL regulatory network of G. biloba in different organs was revealed by different transcriptomic analysis strategies. Weighted gene co-expression network analysis (WGCNA) revealed that the five modules were closely correlated with organs. The 12 transcription factors, 5 structural genes and 24 Cytochrome P450 (CYP450) were identified as candidate regulators for TTL accumulation by WGCNA and cytoscape visualization. Finally, 6 APETALA2/ethylene response factors, 2 CYP450s and bHLH were inferred to regulate the metabolism of TTLs by correlation analysis. This study is the comprehensive in authenticating transcription factors, structural genes and CYP450 involved in TTL biosynthesis, thereby providing molecular evidence for revealing the comprehensive regulatory network involved in TTL metabolism in G. biloba.

Dynamic transcriptome and network-based analysis of yellow leaf mutant Ginkgo biloba

BACKGROUND

Golden leaf in autumn is a prominent feature of deciduous tree species like Ginkgo biloba L., a landscape tree widely cultivated worldwide. However, little was known about the molecular mechanisms of leaf yellowing, especially its dynamic regulatory network. Here, we performed a suite of comparative physiological and dynamic transcriptional analyses on the golden-leaf cultivar and the wild type (WT) ginkgo to investigate the underlying mechanisms of leaf yellowing across different seasons.

RESULTS

In the present study, we used the natural bud mutant cultivar with yellow leaves "Wannianjin" (YL) as materials. Physiological analysis revealed that higher ratios of chlorophyll a to chlorophyll b and carotenoid to chlorophyll b caused the leaf yellowing of YL. On the other hand, dynamic transcriptome analyses showed that genes related to chlorophyll metabolism played key a role in leaf coloration. Genes encoding non-yellow coloring 1 (NYC1), NYC1-like (NOL), and chlorophyllase (CLH) involved in the degradation of chlorophyll were up-regulated in spring. At the summer stage, down-regulated HEMA encoding glutamyl-tRNA reductase functioned in chlorophyll biosynthesis, while CLH involved in chlorophyll degradation was up-regulated, causing a lower chlorophyll accumulation. In carotenoid metabolism, genes encoding zeaxanthin epoxidase (ZEP) and 9-cis-epoxy carotenoid dioxygenase (NCED) showed significantly different expression levels in the WT and YL. Moreover, the weighted gene co-expression network analysis (WGCNA) suggested that the most associated transcriptional factor, which belongs to the AP2/ERF-ERF family, was engaged in regulating pigment metabolism. Furthermore, quantitative experiments validated the above results.

CONCLUSIONS

By comparing the golden-leaf cultivar and the wide type of ginkgo across three seasons, this study not only confirm the vital role of chlorophyll in leaf coloration of YL but also provided new insights into the seasonal transcriptome landscape and co-expression network. Our novel results pinpoint candidate genes for further wet-bench experiments in tree species.

Production of medium-chain fatty acids by co-fermentation of antibiotic fermentation residue with fallen Ginkgo leaves

The co-fermentation of antibiotic fermentation residues (AFRs) and fallen Ginkgo leaves at C/N ratios of 10-60 was conducted for medium-chain fatty acids (MCFA) production. It was found that a proper C/N ratio could largely promote the MCFA accumulation. Group with C/N ratio of 50 exhibited highest MCFA production of 133.14 mmol C/L, which was 42 %-121 % higher than the other groups. Through the co-fermentation, substrate condition was optimized with rich micro-nutrients in AFRs and abundant polysaccharides in Ginkgo leaves, the hydrolysis of leaves was promoted by the active microbes in AFRs, and the predominance of CE microbes was also stimulated with the dilution of AFRs. The increased C/N ratio significantly affected the SCFA producers like genus Escherichia Shigella and Proteiniphilum, and enriched CE microbes like genus Romboutsia, Eubacterium and Clostridium_sensu_stricto_12. Functional enzymes analysis showed that both reverse β oxidation and fatty acid biosynthesis pathways were strengthened with the increased C/N ratio.

Lead acetate induces hippocampal pyramidal neuron degeneration in mice via up-regulation of executioner caspase-3, oxido-inflammatory stress expression and decreased BDNF and cholinergic activity: Reversal effects of Gingko biloba supplement

PURPOSE

It has been hypothesized that compounds with strong anti-oxidant activity might mitigate lead-induced neurotoxicity that resulted to neuronal degeneration.Ginkgo biloba supplement (GB-S) is a neuroactive supplement which has been reported to demonstrate neuroprotective effects. In this study, we investigated the reversal effect and the underlying mechanism of GB-S following lead-induced neurotoxicity in mice.

METHODS

Male Swiss mice (n = 8) were pre-treated with lead acetate (100 mg/kg) for 30 min before GB-S (10 mg/kg and 20 mg/kg) or Ethylenediaminetetraacetic acid (EDTA) (50 mg/kg) intraperitoneally for 14 consecutive days. Memory impairment symptoms were evaluated on day 13 and 14 using Y-maze and Novel object recognition test (NORT) respectively. Thereafter, spectrophotometry, ELISA, immunohistochemistry and histomorphormetry were used to estimate the degree and expression of biomarkers of neuronal inflammation: oxido-inflammatory stress, apoptosis and degeneration in the hippocampus (HC).

RESULTS

Lead acetate treatment significantly (p < 0.05) induced neurobehavioral impairment which was reversed by GB-S as evident in increased percentage alternation and discrimination index. GB-S significantly (p < 0.05) reduced lipid peroxidation and nitrite level, inhibited TNF-α and acetylcholinesterase activity and improved glutathione, catalase and superoxide dismutase activity in the HC. Moreover, GB-S inhibited hippocampal apoptosis via elevated expression of caspase-3 with marked increase level of brain derived neurotrophic factor (BDNF). Also, the histomorphormetric study showed that GB-S rescued death of pyramidal neurons (CA3) in the HC.

CONCLUSION

Our findings however suggest that GB-S decreased memory impairment progression induced by lead acetate via mechanisms connected to inhibition of oxido-inflammatory stress mediators, restrained acetylcholinesterase activity, up-regulated BDNF/Caspase-3 expression and suppression of hippocampal pyramidal neuron degeneration in mice.

A Mixture of Ginkgo biloba L. Leaf and Hericium erinaceus (Bull.) Pers. Fruit Extract Attenuates Scopolamine-Induced Memory Impairments in Mice

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by loss of memory and cognitive impairment via dysfunction of the cholinergic nervous system. In cholinergic dysfunction, it is well known that impaired cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) signaling are major pathological markers and are some of the strategies for the development of AD therapy. Therefore, this study is aimed at evaluating whether a mixture comprising Ginkgo biloba L. leaf (GL) and Hericium erinaceus (Bull.) Pers. (HE) fruit extract (GH mixture) alleviated cognitive impairment induced in a scopolamine-induced model. It was discovered that GH reduced neuronal apoptosis and promoted neuronal survival by activating BDNF signaling in an in vitro assay. In addition, the GH (p.o. 240 mg/kg) oral administration group significantly restored the cognitive deficits of the scopolamine-induced mouse group (i.p. 1.2 mg/kg) in the behavior tests such as Y-maze and novel object recognition task (NORT) tests. This mixture also considerably enhanced cholinergic system function in the mouse brain. Furthermore, GH markedly upregulated the expressed levels of extracellular signal-regulated kinase (ERK), CREB, and BDNF protein levels. These results demonstrated that GH strongly exerted a neuroprotective effect on the scopolamine-induced mouse model, suggesting that an optimized mixture of GL and HE could be used as a good material for developing functional foods to aid in the prevention of neurodegenerative diseases, including AD.

Overexpression of Ginkgo BBX25 enhances salt tolerance in Transgenic Populus

B-box (BBX) genes play important roles in plant growth, light morphogenesis, and environmental stress responses. Ginkgo (Ginkgo biloba L.) is known as a living fossil species that has a strong ability to adapt to environmental changes and tolerate harsh conditions. In this study, we chose this species to investigate the function of the GbBBX25 gene. We isolated the BBX gene from ginkgo and named it GbBBX25; this gene consists of an 819 bp open reading frame (ORF) that encodes 273 amino acids with two B-box domains but no CCT domain. GbBBX25 was localized in only the nucleus. The expression of GbBBX25 transcripts was observed in the leaves and was significantly enhanced under salt stress conditions. To further verify its function, we overexpressed the GbBBX25 gene in Populus davidiana × Populus bolleana and found that the transgenic Populus had greater soluble sugar levels and higher peroxidase (POD) activity in response to salt stress than nontransgenic (NT) Populus. Five genes related to salt stress were induced in transgenic plants with significantly higher expression levels than those in NT plants. This finding suggests that GbBBX25 improves the salt adaptation abilities of transgenic Populus and provides a scientific basis for related research.

Phenylalanine Increases the Production of Antioxidant Phenolic Acids in Ginkgo biloba Cell Cultures

The aims of this study were to evaluate the antioxidant properties, to investigate the content of major secondary metabolites in Ginkgo biloba cell cultures, and to determine the change in the production of phenolic acids by adding phenylalanine to the culture medium. Three in vitro methods, which depend on different mechanisms, were used for assessing the antioxidant activity of the extract: 1,1-diphenyl-2-picrylhydrazil (DPPH), reducing power and Fe²⁺ chelating activity assays. The extract showed moderate activity both in the DPPH and in the reducing power assays (IC₅₀ = 1.966 ± 0.058 mg/mL; ASE/mL = 16.31 ± 1.20); instead, it was found to possess good chelating properties reaching approximately 70% activity at the highest tested dose. The total phenolic, total flavonoid, and condensed tannin content of G. biloba cell culture extract was spectrophotometrically determined. The phenolic acid content was investigated by RP-HPLC, and the major metabolites—protocatechuic and p-hydroxybenzoic acids—were isolated and investigated by ¹H NMR. The results showed that phenylalanine added to G. biloba cell cultures at concentrations of 100, 150, and 200 mg/150 mL increased the production of phenolic acids. Cultures that were grown for 3 weeks and collected after 4 days of phenylalanine supplementation at high concentration showed maximal content of phenolic acids (73.76 mg/100 g DW).

Effect of Methyl Jasmonate on the Terpene Trilactones, Flavonoids, and Phenolic Acids in Ginkgo biloba L. Leaves: Relevance to Leaf Senescence

The present study compared the effects of natural senescence and methyl jasmonate (JA-Me) treatment on the levels of terpene trilactones (TTLs; ginkgolides and bilobalide), phenolic acids, and flavonoids in the primary organs of Ginkgo biloba leaves, leaf blades, and petioles. Levels of the major TTLs, ginkgolides B and C, were significantly higher in the leaf blades of naturally senesced yellow leaves harvested on 20 October compared with green leaves harvested on 9 September. In petioles, a similar effect was found, although the levels of these compounds were almost half as high. These facts indicate the importance of the senescence process on TTL accumulation. Some flavonoids and phenolic acids also showed changes in content related to maturation or senescence. Generally, the application of JA-Me slightly but substantially increased the levels of TTLs in leaf blades irrespective of the difference in its application side on the leaves. Of the flavonoids analyzed, levels of quercetin, rutin, quercetin-4-glucoside, apigenin, and luteolin were dependent on the JA-Me application site, whereas levels of (+) catechin and (−) epicatechin were not. Application of JA-Me increased ferulic acid and p-coumaric acid esters in the petiole but decreased the levels of these compounds in the leaf blade. The content of p-coumaric acid glycosides and caffeic acid esters was only slightly modified by JA-Me. In general, JA-Me application affected leaf senescence by modifying the accumulation of ginkogolides, flavonoids, and phenolic acids. These effects were also found to be different in leaf blades and petioles. Based on JA-Me- and aging-related metabolic changes in endogenous levels of the secondary metabolites in G. biloba leaves, we discussed the results of study in the context of basic research and possible practical application.

A novel method for ginkgolide biosynthesis elucidation based on MeJA induction and differential metabolomics

Ginkgolides from Ginkgo Biloba have significantly therapeutic effect to cardiovascular and cerebrovascular diseases. However, the biosynthetic pathway of ginkgolides has not been fully elucidated until now. As ginkgolides are synthesized in the ginkgo roots, the accumulation of ginkgolides intermediate metabolites varies greatly between roots and leaves. As Methyl jasmonate (MeJA) can effectively enhance the biosynthesis of ginkgolides, a novel method based on MeJA induction and differential metabolomics was used to screen the differentially intermediate metabolites among ginkgo leaves, roots and roots-MJ-3. Two differential intermediate metabolites (dehydroabietadienal and 1, 2, 3, 4, 4a, 9, 10, 10a-Octahydro-6-hydroxy-7-isopropyl-1, 4a-dimethyl-1-phenanthrenemethanol) were identified in ginkgo roots by UPLC-QTOF-MS. Then, a new ginkgolides biosynthetic pathway was proposed based on differential metabolomics. This study provides a novel method for the elucidation of nature product precursor and is helpful to promote the clarification of ginkgolides biosynthetic pathway.

Neuroprotective Herbs for the Management of Alzheimer's Disease

Background—Alzheimer’s disease (AD) is a multifactorial, progressive, neurodegenerative disease that is characterized by memory loss, personality changes, and a decline in cognitive function. While the exact cause of AD is still unclear, recent studies point to lifestyle, diet, environmental, and genetic factors as contributors to disease progression. The pharmaceutical approaches developed to date do not alter disease progression. More than two hundred promising drug candidates have failed clinical trials in the past decade, suggesting that the disease and its causes may be highly complex. Medicinal plants and herbal remedies are now gaining more interest as complementary and alternative interventions and are a valuable source for developing drug candidates for AD. Indeed, several scientific studies have described the use of various medicinal plants and their principal phytochemicals for the treatment of AD. This article reviews a subset of herbs for their anti-inflammatory, antioxidant, and cognitive-enhancing effects. Methods—This article systematically reviews recent studies that have investigated the role of neuroprotective herbs and their bioactive compounds for dementia associated with Alzheimer’s disease and pre-Alzheimer’s disease. PubMed Central, Scopus, and Google Scholar databases of articles were collected, and abstracts were reviewed for relevance to the subject matter. Conclusions—Medicinal plants have great potential as part of an overall program in the prevention and treatment of cognitive decline associated with AD. It is hoped that these medicinal plants can be used in drug discovery programs for identifying safe and efficacious small molecules for AD.

Submerged fermentation of Ginkgo biloba seed powder using Eurotium cristatum for the development of ginkgo seeds fermented products

BACKGROUND

Ginkgo biloba seeds are well known for the significant curative effects on relieving cough and asthma. However, the development of products from ginkgo seeds still falls behind at present, resulting in a great waste of ginkgo seeds' resource. In this work, submerged fermentation of ginkgo seed powder using Eurotium cristatum was studied to investigate its feasibility as a new processing method.

RESULTS

To promote the growth of E. cristatum, the optimum fermentation medium was 80.0 g L^-1 of ginkgo seed powder with addition of 5.0 g L^-1 calcium chloride (CaCl₂ ), 4.0 g L^-1 magnesium sulfate (MgSO₄ ), 1.25 g L^-1 zinc sulfate (ZnSO₄ ) and 0.65 g L^-1 iron(II) sulfate (FeSO₄ ). The optimum fermentation conditions were pH 5.8 ± 0.1, inoculum size 5.1 × 10⁶  CFU mL^-1 , liquid medium volume 100 mL in 250-mL Erlenmeyer flask and fermentation 4 days. Through fermentation, the production of lovastatin in fermentation broth could reach up to 32.97 ± 0.17 μg mL^-1 and the total antioxidant capacity was improved by more than two-fold. In addition, 40.15% of the ginkgotoxin in ginkgo seed powder was degraded while the entire degradation of ginkgolic acids was obtained. Moreover, fermented ginkgo seed powder suspension presented pleasant fragrances, and the activities of amylase and protease were enhanced to 11.30 ± 0.10 U mL^-1 and 23.01 ± 0.20 U mL^-1 , respectively.

CONCLUSIONS

Submerged fermentation using E. cristatum could significantly enhance the functional value and safety of ginkgo seed powder, and had great potential to become a novel processing method for the development of ginkgo seeds fermented products. © 2020 Society of Chemical Industry.

Functional analysis of a novel cryptochrome gene (GbCRY1) from Ginkgo biloba

Cryptochrome (CRY) is a blue light receptor that is widely distributed in animals, plants, and microorganisms. CRY as a coding gene of cryptochrome that regulates the organism gene expression and plays an important role in organism growth and development. In this study, we identified four photolyase/cryptochrome (PHR/CRY) members from the genome of Ginkgo biloba. Phylogenetic tree analysis showed that the Ginkgo PHR/CRY family members were closely related to Arabidopsis thaliana and Solanum lycopersicum. We isolated a cryptochrome gene, GbCRY1, from G. biloba and analyzed its structure and function. GbCRY1 shared high similarity with AtCRY1 from A. thaliana. GbCRY1 expression level was higher in stems and leaves and lower in roots, male strobili, female strobili. GbCRY1 expression level fluctuated periodically within 24 h, gradually increased in the dark, and decreased under blue light. The newly germinated ginkgo seedlings were cultured under dark, white light, and blue light conditions. The blue light normally induced photomorphogenesis of ginkgo seedlings, which included hypocotyl elongation inhibition, leaf expansion inhibition, and chlorophyll formation. Treating dark-adapted ginkgo leaves with blue light could induce stomatal opening. At the same time, blue light reduced the expression level of GbCRY1 in the process of inducing photomorphogenesis and stoma opening. Our results provide evidence that GbCRY1 expression is affected by space, circadian cycle and light, and also proves that GbCRY1 is related to ginkgo circadian clock, photomorphogenesis and stoma opening process.

Physiological, Transcriptomic, and Metabolic Responses of Ginkgo biloba L. to Drought, Salt, and Heat Stresses

Ginkgo biloba L. is highly adaptable and resistant to a range of abiotic stressors, allowing its growth in various environments. However, it is unclear how G. biloba responds to common environmental stresses. We explored the physiological, transcriptomic, and metabolic responses of G. biloba to short-term drought, salt, and heat stresses. Proline, H₂O₂, and ABA contents, along with CAT activity, increased under all three types of stress. SOD activity increased under salt and heat stresses, while soluble protein and IAA contents decreased under drought and salt stresses. With respect to metabolites, D-glyceric acid increased in response to drought and salt stresses, whereas isomaltose 1, oxalamide, and threonine 2 increased under drought. Piceatannol 2,4-hydroxybutyrate and 1,3-diaminopropane increased under salt stress, whereas 4-aminobutyric acid 1 and galactonic acid increased in response to heat stress. Genes regulating nitrogen assimilation were upregulated only under drought, while the GRAS gene was upregulated under all three types of stressors. ARF genes were downregulated under heat stress, whereas genes encoding HSF and SPL were upregulated. Additionally, we predicted that miR156, miR160, miR172, and their target genes participate in stress responses. Our study provides valuable data for studying the multilevel response to drought, salinity, and heat in G. biloba.

The genomic architecture of the sex-determining region and sex-related metabolic variation in Ginkgobiloba

Sex differences and evolutionary differences are critical biological issues. Ginkgo is an ancient lineage of dioecious gymnosperms with special value for studying the mechanism of sex determination in plants. However, the major genetic basic underlying sex chromosomes remains to be uncovered. In this study, we identify the sex-determining region of Ginkgo and locate it to the area from megabases 48 to 75 on chromosome 2. We find that the male sex-determining region of Ginkgo contains more than 200 genes, including four MADS-box genes, demonstrating that the Ginkgo sex determination system is of the XY type. We also find that genetic sex differences result in specialized flavonoid metabolism and regulation in each sex. These findings establish a foundation for revealing the molecular mechanism of sexual dimorphism and promoting the development of the Ginkgo industry.