Plant Secondary Metabolism Research Articles

Rhizosphere metagenomics provides insights into the environmental effect on the secondary metabolism of Ligusticum chuanxiong

Rhizosphere microbiomes influence the secondary metabolism of plants, but the mechanism has not been analyzed. This study aimed to explore relationship between abiotic environments, microbiomes and secondary metabolites of Ligusticum chuanxiong. By combining metagenomic, metatranscriptomic, and high-performance liquid chromatography, the microbial community structure and key microbiomes in Ligusticum chuanxiong were identified. Furthermore, the relationship between root-associated microbiomes and the secondary metabolites in Ligusticum chuanxiong was revealed. The microbial community structures of L. chuanxiong differed in each individual. The key microbiome related to secondary metabolism were similar, while there were significant differences in relative abundance across all samples. Four families (Burkholderiaceae, Comamonadaceae, Pseudomonadaceae, and Streptomycetaceae) and four species (Gemmatirosa kalamazoonesis, Luteitalea pratensis, Candidatus Solibacter usitatus, and Sorangium cellulosum) were identified as conservative core microbes, and Chloroflexi was the main biomarker. Functional annotation results showed that the metabolic function strength of the microbial community was positively correlated with the secondary metabolite content. According to correlation results, rhizosphere microbiomes related with secondary metabolites in two aspects including community diversity and microbial abundance. In conclusion, environmental factors might affect secondary metabolites of Ligusticum chuanxiong Hort. by influencing microbial diversity and the abundance of key microbes. This study can provide references for improving the artificial cultivation of Ligusticum chuanxiong, further developing and utilizing this medicinal resource.

Csn-miR156d-CsSPL1 regulates flowering and anthocyanin metabolism.

MiR156 play important roles in regulation of plant growth and development, secondary metabolite synthesis, and other biological processes by targeting the SQUAMOSA promoter binding protein-like (SPL) family. Our previous sequencing data analysis suggested that Csn-miR156d may regulate flowering and anthocyanin accumulation by cleavage and degradation of the expression of the SPL in tea plant, but it remains to be elucidated. In this study, 5'RLM-RACE experiment, tobacco transient transformation, qRT-PCR, and antisense oligonucleotide (asODN) were used to verify that CsSPL1 is the target gene of Csn-miR156d. Stable transformation of Arabidopsis revealed that Csn-miR156d could delay flowering by negatively regulating the transcript levels of FT, AP1, FUL, and SOC1, while overexpression of CsSPL1 showed an opposite effect. Additionally, overexpression of Csn-miR156d in Arabidopsis could enhance the transcription of the anthocyanin biosynthesis-related structural genes DFR, ANS, F3H, UGT78D2, and LDOX, as well as regulatory genes PAP1, MYB113, GL3, MYB11, and MYB12, leading to anthocyanin accumulation. Moreover, asODN experiment revealed that Csn-miR156d could increase the anthocyanin content in tea plant. These results suggest that Csn-miR156d regulates flowering and anthocyanin accumulation in tea plant by suppressing the expression of CsSPL1. Our study provides new insights into the development and anthocyanin accumulation in tea plant and lays a theoretical foundation for further research on the molecular mechanism of miRNAs in regulating tea plant growth and secondary metabolism.

Application of chitosan nanopriming on plant growth and secondary metabolites of Pancratium maritimum L

BackgroundNanotechnology has demonstrated its vital significance in all aspects of daily life. Our research was conducted to estimate the potential of primed seed with chitosan nanoparticles in seed growth and yield by inducing plant secondary metabolism of Pancratium maritimum L. one of the important medicinal plants. Petri dish and pot experiments were carried out. Seeds of Pancratium maritimum L. were soaked in Nano solution (0.1, 0.5, 1 mg/ ml) for 4, 8, 12 h. Germination parameters (germination percentage, germination velocity, speed of germination, germination energy, germination index, mean germination time, seedling shoot and root length, shoot root ratio, seedling vigor index, plant biomass and water content), alkaloids and antioxidant activity of Pancratium maritimum L. were recorded and compared between coated and uncoated seeds.ResultsOur results exhibited that chitosan nanopriming had a positive effect on some growth parameters, while it fluctuated on others. However, the data showed that most germination parameters were significantly affected in coated seeds compared to uncoated seeds. GC-MS analysis of Pancratium maritimum L. with different nanopriming treatments showed that the quantity of alkaloids decreased, but the amount of pancratistatin, lycorine and antioxidant content increased compared with the control.ConclusionsApplying chitosan nanoparticles in priming seeds might be a simple and effective way to improve the quantity of secondary metabolites of Pancratium maritimum L. valuable medicinal plant.

Single-repeat MYB transcription factor, OsMYB1R, enhanced phytoalexin sakuranetin accumulation and Magnaporthe oryzae resistance

Sakuranetin, a flavonoid phytoalexin in rice, plays a crucial role in defense against pathogen infection. While MYB-type transcription factors are well-known to regulate plant growth, development, secondary metabolism, and adaptation to environmental stresses, the function of rice MYB-related transcription factors in sakuranetin biosynthesis and sakuranetin-mediated defense remains unclear. In this study, we identified and characterized OsMYB1R, a novel single repeat MYB transcription factor that acts as a transcriptional activator in sakuranetin biosynthesis. Protein-DNA binding and activation assays revealed that OsMYB1R directly regulates the gene promoter of OsNOMT, a key enzyme in sakuranetin synthesis. Molecular analyses and infection studies using OsMYB1R-overexpressing (OsMYB1R-OE) and OsMYB1R-knockout (Osmyb1r, generated using CRISPR/Cas9) plants demonstrated that OsMYB1R increases sakuranetin production and decreases Magnaporthe oryzae infection by transcriptionally regulating OsNOMT expression. This finding indicates a positive regulation of sakuranetin biosynthesis and antifungal resistance by the OsMYB1R-OsNOMT crosstalk. Interestingly, the alteration of OsMYB1R expression did not affect yield-related agronomic traits. Our results reveal a novel and positive role of 1R-MYB in secondary metabolite biosynthesis and pathogen defense, suggesting that OsMYB1R is a potential gene for effectively enhancing rice resistance without compromising yield.

Volatile Constituents of Some Myrtaceous Edible and Medicinal Fruits from the Brazilian Amazon.

Native and exotic fruits from the Amazon have varied characteristics, with aroma being a decisive factor in their acceptance for medicinal use as a nutraceutical supplement. This work aimed to analyze the chemical constituents of the volatile concentrates of some Myrtaceous fruit species sampled in the Brazilian Amazon. The fruit's pulps were subjected to simultaneous distillation-extraction, and gas chromatography-mass spectrometry was used to analyze their volatile chemical composition. In the volatile concentrate of Eugenia stipitata (Araçá-boi) α-pinene (17.5%), citronellyl butanoate (15.6%), and pogostol (13.5%) were identified as primary constituents; Eugenia uniflora (Ginja) concentrate comprised curzerene (30.5%), germacrone (15.4%), atractylone (13.1%), and (E)-β-ocimene (11.1%); in Myrciaria dubia (Camu-Camu), α-pinene (55.8%), (E)-β-ocimene (13.1%), and α-terpineol (10.0%) were present; in Psidium guajava (Goiaba) were (2E)-hexenal (21.7%), hexanal (15.4%), caryophylla-4(12),8(13)-dien-5-β-ol (10.5%), caryophyllene oxide (9.2%), and pogostol (8.3%); and in Psidium guineense (Araçá), limonene (25.2%), ethyl butanoate (12.1%), epi-β-bisabolol (9.8%), and α-pinene (9.2%) were the main constituents. The analyzed volatile concentrates of these fruit species presented a significant diversity of constituents with a predominance of functional groups, such as monoterpenes, sesquiterpenes, and fatty acid derivatives, originating from the plant's secondary metabolism and playing an important role in their nutritional and medicinal uses.

Plant‐mediated facilitation to conspecifics and heterospecifics by two phloem‐feeding maize pests: The influence of insect identity and order of arrival

Abstract Herbivory by insects leads to changes in both primary and secondary plant metabolism, ultimately impacting subsequent interactions. Some phloem‐feeding insects have developed mechanisms to suppress herbivore‐induced plant defences and manipulate the quality of host phloem sap, thereby facilitating their establishment on the host plant. Based on evidence that the specialized phloem‐feeding insects, Dalbulus maidis and Rhopalosiphum maidis, can suppress herbivore‐induced defences in maize, we hypothesized that infestation by either of these pests in maize would facilitate the colonization and establishment of subsequent conspecific and heterospecific individuals. We conducted a series of behavioural assays with these insects in both laboratory and greenhouse settings. The corn leafhopper D. maidis preferred previously infested plants as hosts, but it did not discriminate between conspecific‐ or heterospecific‐infested plants for colonization. However, when selecting a host for oviposition, it preferred depositing eggs on conspecific‐infested plants, which were the hosts that the offspring performed better compared to both non‐infested and heterospecific‐infested plants. The corn aphid R. maidis also preferred previously infested plants over non‐infested plants as hosts. However, the aphid preferred heterospecific‐infested over conspecific‐infested plants, even though heterospecific‐infested plants were hosts of lower quality to aphids. Aphids performed better on conspecific‐infested plants, followed by heterospecific‐infested plants, when compared to non‐infested plants. Our results confirm that previous colonization by the specialized phloem‐feeding insects facilitates subsequent infestations by conspecifics and heterospecifics. However, the facilitation for heterospecifics was asymmetric, as colonization by D. maidis facilitated infestations by R. maidis more than the reverse sequence of infestation.

The apple MdGA2ox7 modulates the balance between growth and stress tolerance in an anthocyanin-dependent manner

Apple (Malus domestica Borkh.) is a widely cultivated fruit crop worldwide but often suffers from abiotic stresses such as salt and cold. Gibberellic acid (GA) plays a pivotal in controlling plant development, environmental adaptability, and secondary metabolism. The GA2-oxidase (GA2ox) is responsible for the deactivation of bioactive GA. In this study, seventeen GA2-oxidase genes were identified in the apple genome, and these members could be clustered into four clades based on phylogenetic relationships and conserved domain structures. MdGA2ox7 exhibited robust expression across various tissues, responded to cold and salt treatments, and was triggered in apple fruit peels via light-induced anthocyanin accumulation. Subcellular localization prediction and experiments confirmed that MdGA2ox7 was located in the cytoplasm. Overexpression of MdGA2ox7 in Arabidopsis caused a lower level of active GA and led to GA-deficient phenotypes, such as dwarfism and delayed flowering. MdGA2ox7 alleviated cold and salt stress damage in both Arabidopsis and apple in concert with melatonin (MT). Additionally, MdGA2ox7 enhanced anthocyanin biosynthesis in apple calli and activated genes involved in anthocyanin synthesis. These findings provide new insights into the functions of apple GA2ox in regulating development, stress tolerance, and secondary metabolism.

Exogenous curcumin mitigates As stress in spinach plants: A biochemical and metabolomics investigation

The spinach (S. oleracea L.) was used as a model plant to investigate As toxicity on physio-biochemical processes, exploring the potential mitigation effect of curcumin (Cur) applied exogenously at three concentrations (1, 10, and 20 μM Cur). The employment of Cur significantly mitigated As-induced stress in spinach photosynthetic performance (Fv/Fm, Fo/Fm, and Fv/Fo). Moreover, the co-incubation of Cur with As improved physiological processes mainly associated with plant water systems affected by As stress by recovering the leaf's relative water content (RWC) and osmotic potential (ψπ) nearly to the control level and increasing the transpiration rate (E; 39–59%), stomatal conductivity (gs; 86–116%), and carbon assimilation rate (A; 84–121%) compared to As stressed plants. The beneficial effect of Cur in coping with As-induced stress was also assessed at the plant's oxidative level by reducing oxidative stress biomarkers (H2O2 and MDA) and increasing non-enzymatic antioxidant capacity.Untargeted metabolomics analysis was adopted to investigate the main processes affected by As and Cur application. A multifactorial ANOVA discrimination model (AMOPLS-DA) and canonical correlation analysis (rCCA) were employed to identify relevant metabolic changes and biomarkers associated with Cur and As treatments. The results highlighted that Cur significantly determined the accumulation of glucosinolates, phenolic compounds, and an increase in glutathione redox cycle activities, suggesting an overall elicitation of plant secondary metabolisms. Specifically, the correlation analysis reported a strong and positive correlation between (+)-dihydrokaempferol, L-phenylalanine (precursor of phenolic compounds), and serotonin-related metabolites with antioxidant activities (ABTS and DPPH), suggesting the involvement of Cur application in promoting a cross-talk between ROS signaling and phytohormones, especially melatonin and serotonin, working coordinately to alleviate As-induced oxidative stress. The modulation of plant metabolism was also observed at the level of amino acids, fatty acids, and secondary metabolites synthesis, including N-containing compounds, terpenes, and phenylpropanoids to cooperate with As-induced stress response.

Selenium nanoparticles induce coumarin metabolism and essential oil production in Trachyspermum ammi under future climate CO2 conditions.

Research on nanoparticles (NPs) and future elevated CO2 (eCO2) is extensive, but the effects of SeNPs on plant growth and secondary metabolism under eCO2 remain uncertain. In this study, we explored the impact of SeNPs and/or eCO2 on the growth, physiology, chemical composition (primary metabolites, coumarins, and essential oils), and antioxidant capacity of Trachyspermum (T.) ammi. The treatment with SeNPs notably improved the biomass and photosynthesis of T. ammi plants, particularly under eCO2 conditions. Plant fresh and dry weights were improved by about 19, 33 and 36% in groups treated by SeNPs, eCO2, and SeNPs + eCO2, respectively. SeNPs + eCO2 induced photosynthesis, consequently enhancing sugar and amino acid levels. Similar to the increase in total sugars, amino acids showed variable enhancements ranging from 6 to 42% upon treatment with SeNPs + eCO2. At the level of the secondary metabolites, SeNPs + eCO2 substantially augmented coumarin biosynthesis and essential oil accumulation. Consistently, there were increases in coumarins and essential oil precursors (shikimic and cinnamic acids) and their biosynthetic enzymes. The enhanced accumulation of coumarins and essential oils resulted in increased overall antioxidant activity, as evidenced by improvements in FRAP, ORAC, TBARS, conjugated dienes, and inhibition % of hemolysis. Conclusively, the application of SeNPs demonstrates significant enhancements in plant growth and metabolism under future CO2 conditions, notably concerning coumarin metabolism and essential oil production of T. ammi.

EDUKASI AKTIVITAS ANTIMIKROBA PADA TANAMAN RIMPANG DI WILAYAH KELURAHAN DUREN SAWIT

Medicinal plants are plants that have properties for preventing and treating disease. Medicinal plants have properties because they contain active compounds resulting from secondary plant metabolism, namely flavonoids, alkaloids, phenols, tannins, saponins, triterpenoids and steroids. Red ginger is a medicinal plant that has been widely studied because it has antibacterial activity. Based on the results of discussions with representatives Duren Sawit Subdistrict, it was found that there had been no education to the public regarding antimicrobial activity in rhizome plants. The aim of this community service is to increase public knowledge regarding the antibacterial potential of native Indonesian rhizome plants. The method used int this activity is providing education through counseling. The results obtained from this activity showed an increase in community knowledge scores before and after being given education about antibacterial rhizome plants.

Changes in secondary metabolites contents and stress responses in Salvia miltiorrhiza via ScWRKY35 overexpression: Insights from a wild relative Salvia castanea

Salvia castanea Diels, a close wild relative to the medicinal plant, Salvia miltiorrhiza Bunge, primarily grows in high-altitude regions. While the two species share similar active compounds, their content varies significantly. WRKY transcription factors are key proteins, which regulate plant growth, stress response, and secondary metabolism. We identified 46 ScWRKY genes in S. castanea and found that ScWRKY35 was a highly expressed gene associated with secondary metabolites accumulation. This study aimed to explore the role of ScWRKY35 gene in regulating the accumulation of secondary metabolites and its response to UV and cadmium (Cd) exposure in S. miltiorrhiza. It was found that transgenic S. miltiorrhiza hairy roots overexpressing ScWRKY35 displayed upregulated expression of genes related to phenolic acid synthesis, resulting in increased salvianolic acid B (SAB) and rosmarinic acid (RA) contents. Conversely, tanshinone pathway gene expression decreased, leading to lower tanshinone levels. Further, overexpression of ScWRKY35 upregulated Cd transport protein HMA3 in root tissues inducing Cd sequestration. In contrast, the Cd uptake gene NRAMP1 was downregulated, reducing Cd absorption. In response to UV radiation, ScWRKY35 overexpression led to an increase in the accumulation of phenolic acid and tanshinone contents, including upregulation of genes associated with salicylic acid (SA) and jasmonic acid (JA) synthesis. Altogether, these findings highlight the role of ScWRKY35 in enhancing secondary metabolites accumulation, as well as in Cd and UV stress modulation in S. miltiorrhiza, which offers a novel insight into its phytochemistry and provides a new option for the genetic improvement of the plants.

A bZIP type transcription factor from Picrorhiza kurrooa modulates the expression of terpenoid biosynthesis genes in Nicotiana benthamiana

bZIP family of transcription factors are DNA-binding proteins which bind ACGT motifs in the upstream promoter region of genes. bZIP proteins play significant roles in regulation of plant growth, secondary metabolism, development, defense and response to various abiotic and biotic stresses. Up to now, there is no report on molecular and functional characterization of bZIP transcription factors in Picrorhiza kurrooa, a medicinally important endangered herb of north western Himalayan region. The species is widely used in several commercially available drug formulations like livomap, livocare and livplus for treatment of liver disorders. The medicinal properties of P. kurrooa are due to bioactive picrosides, synthesized by isoprenoid pathway. The promoters of regulatory genes viz., Pkdxs and Pkhmgr of picroside biosynthesis pathway have been reported to contain ACGT cis-acting elements (bzip motifs) at different locations. In this study, the functionality of ACGT motifs was confirmed by electrophoretic mobility shift assay (EMSA). Full length PkbZIP gene was cloned through RACE method. In silico analysis revealed PkbZIP contained a conserved signature bZIP domain (N-x7-R/K-x9-L-x6-L-x6-L). Transcriptional activation and subcellular localization assay confirmed nuclear localization of PkbZIP. EMSA with purified PkbZIP confirmed in vitro binding of PkbZIP to ACGT elements in Pkdxs and Pkhmgr promoters. The expression pattern of PkbZIP positively correlated with the picroside (active medicinal component of the plant) content in different tissues, at 15 °C and under light conditions. Transient overexpression in Nicotiana benthamiana suggested a role of PkbZIP in terpenoid biosynthesis. PkbZIP might prove as potential candidate gene to be used in genetic engineering program for enhancing the picroside content in P. kurrooa.

Quantification of flavonoids, minerals, and pigments present in "Nanicão" bananas during the ripening process.

Banana is one of the most consumed and popular fruits in all regions of the world, being cultivated mainly in tropical countries. It is not only a rich source of vitamins A, C, and B, calcium, iron, potassium, phosphorus, and other vitamins and nutrients, but it also contains several types of antioxidants with high nutritional value. In this context, the current study aimed to quantify the content of ascorbic acid, flavonoids, pigments, and minerals present in "Nanicão" bananas during the ripening process. As demonstrated, the level of flavonoids was higher in ripe and overripe fruits, whereas the mineral composition was high only at ripening stage 4 (more yellow than green) a stage that should be prioritized when recommending fruit consumption to the population deficient in these minerals. Regarding pigments, there was a reduction in chlorophylls a and b and an increase in carotenoids and anthocyanins in peels and pulps. PRACTICAL APPLICATION: Flavonoids are phenolic, bioactive compounds with proven antioxidant and anti-inflammatory activity and products of the plant's secondary metabolism. The degradation of chlorophylls and synthesis of carotenoids and anthocyanins, and as a consequence of the latter pigment, the increase in flavonoids in the pulp was evident during the monitoring of ripening, mainly in the fruit peels in relation to pigments. Minerals are essential elements, the main ones provided in balanced diets and important for dietary and nutritional health.

Functional characterization, structural basis, and protein engineering of a rare flavonoid 2′-O-glycosyltransferase from Scutellaria baicalensis

Glycosylation is an important post-modification reaction in plant secondary metabolism, and contributes to structural diversity of bioactive natural products. In plants, glycosylation is usually catalyzed by UDP-glycosyltransferases. Flavonoid 2′-O-glycosides are rare glycosides. However, no UGTs have been reported, thus far, to specifically catalyze 2′-O-glycosylation of flavonoids. In this work, UGT71AP2 was identified from the medicinal plant Scutellaria baicalensis as the first flavonoid 2′-O-glycosyltransferase. It could preferentially transfer a glycosyl moiety to 2′-hydroxy of at least nine flavonoids to yield six new compounds. Some of the 2′-O-glycosides showed noticeable inhibitory activities against cyclooxygenase 2. The crystal structure of UGT71AP2 (2.15 Å) was solved, and mechanisms of its regio-selectivity was interpreted by pKa calculations, molecular docking, MD simulation, MM/GBSA binding free energy, QM/MM, and hydrogen‒deuterium exchange mass spectrometry analysis. Through structure-guided rational design, we obtained the L138T/V179D/M180T mutant with remarkably enhanced regio-selectivity (the ratio of 7-O-glycosylation byproducts decreased from 48% to 4%) and catalytic efficiency of 2′-O-glycosylation (kcat/Km, 0.23 L/(s·μmol), 12-fold higher than the native). Moreover, UGT71AP2 also possesses moderate UDP-dependent de-glycosylation activity, and is a dual function glycosyltransferase. This work provides an efficient biocatalyst and sets a good example for protein engineering to optimize enzyme catalytic features through rational design.

Nitrogen Sources Reprogram Carbon and Nitrogen Metabolism to Promote Andrographolide Biosynthesis in Andrographis paniculata (Burm.f.) Nees Seedlings.

Carbon (C) and nitrogen (N) metabolisms participate in N source-regulated secondary metabolism in medicinal plants, but the specific mechanisms involved remain to be investigated. By using nitrate (NN), ammonium (AN), urea (UN), and glycine (GN), respectively, as sole N sources, we found that N sources remarkably affected the contents of diterpenoid lactone components along with C and N metabolisms reprograming in Andrographis paniculata, as compared to NN, the other three N sources raised the levels of 14-deoxyandrographolide, andrographolide, dehydroandrographolide (except UN), and neoandrographolide (except AN) with a prominent accumulation of farnesyl pyrophosphate (FPP). These N sources also raised the photosynthetic rate and the levels of fructose and/or sucrose but reduced the activities of phosphofructokinase (PFK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoenolpyruvate carboxylase (PEPC) and pyruvate dehydrogenase (PDH). Conversely, phosphoenolpyruvate carboxykinase (PEPCK) and malate enzyme (ME) activities were upregulated. Simultaneously, citrate, cis-aconitate and isocitrate levels declined, and N assimilation was inhibited. These results indicated that AN, UN and GN reduced the metabolic flow of carbohydrates from glycolysis into the TCA cycle and downstream N assimilation. Furthermore, they enhanced arginine and GABA metabolism, which increased C replenishment of the TCA cycle, and increased ethylene and salicylic acid (SA) levels. Thus, we proposed that the N sources reprogrammed C and N metabolism, attenuating the competition of N assimilation for C, and promoting the synthesis and accumulation of andrographolide through plant hormone signaling. To obtain a higher production of andrographolide in A. paniculata, AN fertilizer is recommended in its N management.

NaCl elicitation enhances metabolite accumulation and stress resilience in Inula crithmoides L. shoot cultures: implications for its nutritional and medicinal value

This study explored the impact of sodium chloride (NaCl) elicitation on the accumulation of primary and secondary metabolites and the oxidative stress responses of Inula crithmoides L. (golden samphire) in vitro shoot cultures. Elicitation involved applying different concentrations of NaCl (0, 50, 100, and 200 mM) for 4 weeks. This was followed by assessing its impact on plant growth, physiological parameters (pigments, hydrogen peroxide content, total soluble sugars and proteins, and proline), and secondary metabolism (phenylalanine ammonia-lyase activity, shikimic acid, phenolics, flavonoids, and hydroxycinnamic acids) in the shoots. The extracts were also analysed using high-performance liquid chromatography (HPLC). The NaCl elicitation did not affect shoot growth but increased physiological functions such as photosynthesis and oxidative stress management under moderate salinity levels. In addition, NaCl treatments increased the synthesis of soluble sugars and proteins, particularly proline, as well as bioactive phenolics such as gentisic acid, chlorogenic acid, 4-hydroxybenzoic acid, luteolin-7-O-glucoside, and naringenin-7-O-glucoside. The NaCl elicitation in golden samphire shoot cultures offers a significant method for enhancing the production of important nutritional and bioactive compounds. This underscores the species’ potential for cultivation in saline environments and provides valuable prospects for its utilization in the health and nutrition sectors.

Genome-Wide Analysis of the LBD Gene Family in Melon and Expression Analysis in Response to Wilt Disease Infection.

LBD transcription factors are a class of transcription factors that regulate the formation of lateral organs, establish boundaries, and control secondary metabolism in plants. In this study, we identified 37 melon LBD transcription factors using bioinformatics methods and analyzed their basic information, chromosomal location, collinearity, evolutionary tree, gene structure, and expression patterns. The results showed that the genes were unevenly distributed across the 13 chromosomes of melon plants, with tandem repeats appearing on chromosomes 11 and 12. These 37 transcription factors can be divided into two major categories, Class I and Class II, and seven subfamilies: Ia, Ib, Ic, Id, Ie, IIa, and IIb. Of the 37 included transcription factors, 25 genes each contained between one to three introns, while the other 12 genes did not contain introns. Through cis-acting element analysis, we identified response elements such as salicylic acid, MeJA, abscisic acid, and auxin, gibberellic acid, as well as light response, stress response, and MYB-specific binding sites. Expression pattern analysis showed that genes in the IIb subfamilies play important roles in the growth and development of various organs in melon plants. Expression analysis found that the majority of melon LBD genes were significantly upregulated after infection with wilt disease, with the strongest response observed in the stem.

Genome-Wide Identification and Expression Pattern Analysis of BAHD Acyltransferase Family in Taxus mairei.

BAHD acyltransferases are involved in catalyzing and regulating the secondary metabolism in plants. Despite this, the members of BAHD family and their functions have not been reported in the Taxus species. In this study, a total of 123 TwBAHD acyltransferases from Taxus wallichiana var. mairei genome were identified and divided into six clades based on phylogenetic analysis, of which Clade VI contained a Taxus-specific branch of 52 members potentially involved in taxol biosynthesis. Most TwBAHDs from the same clade shared similar conserved motifs and gene structures. Besides the typical conserved motifs within the BAHD family, the YPLAGR motif was also conserved in multiple clades of T. mairei. Moreover, only one pair of tandem duplicate genes was found on chromosome 1, with a Ka/Ks ratio < 1, indicating that the function of duplicate genes did not differentiate significantly. RNA-seq analysis revealed different expression patterns of TwBAHDs in MeJA induction and tissue-specific expression experiments. Several TwBAHD genes in the Taxus-specific branch were highly expressed in different tissues of T. mairei, suggesting an important role in the taxol pathway. This study provides comprehensive information for the TwBAHD gene family and sets up a basis for its potential functions.

GROWTH AND ACCUMULATION OF PHENOLIC COMPOUNDS IN THYME (Thymus vulgaris) BASED ON THE BALANCE OF RED AND BLUE LED LIGHTS

The new plant production methods that use artificial light to replace or complement sunlight have proven that changes in the wavelength of incidental light result in variations in growth, development and secondary metabolism of plants, depending on the genotype and other environmental conditions. However, these methods have been scarcely studied in medicinal and edible plants. The aim of this study was to determine the response of thyme plants (Thymus vulgaris) under different wavelengths. The plants were exposed to red light (660 nm), blue light (440 nm), white light and two proportions of red-blue for 16 hours a day at an intensity of 25 µmol m−2 s−1. The treatments were isolated from sunlight and from each other. Red light was found to promote the formation of etiolated plants, with a low accumulation of chlorophyll, dry matter and phenolic compounds compared to the white light treatment. Blue light generated compact plants with a higher accumulation of chlorophyll and dry matter than red light, but similar to the white light treatment. In terms of phenolic compounds, accumulation was higher under the two latter treatments. The planting of thyme under a combination of blue-red light at a 3:1 ratio was found to result in a compact growth and to improve the accumulation of phenolic compounds.

Identification and Expression Analysis of R2R3-MYB Transcription Factors Associated with Flavonoid Biosynthesis in Panax quinquefolius.

Panax quinquefolius L. is an important medicinal plant, and flavonoids are among its main secondary metabolites. The R2R3-MYB transcription factor plays an irreplaceable role in plant growth, development, and secondary metabolism. In our study, we identified 159 R2R3-MYBs and analyzed their physical and chemical properties in P. quinquefolius. The protein length of 159 PqMYBs varied from 107 to 1050 amino acids. The molecular weight ranged from 12.21 to 116.44 kDa. The isoelectric point was between 4.57 and 10.34. We constructed a phylogenetic tree of P. quinquefolius and Arabidopsis thaliana R2R3-MYB family members, and PqMYB members were divided into 33 subgroups. Transcriptome data analysis showed that the expression patterns of PqMYBs in root, leaf, and flower were significantly different. Following the MeJA treatment of seedlings, five candidate PqMYB genes demonstrated a response. A correlation analysis of PqMYBs and candidate flavonoid pathway genes showed that PqMYB2, PqMYB46, and PqMYB72 had correlation coefficients that were higher than 0.8 with PqCHS, PqANS4, and PqCCoAMT10, respectively. Furthermore, a transient expression assay confirmed that the three PqMYBs were localized in the nucleus. We speculated that these three PqMYBs were related to flavonoid biosynthesis in P. quinquefolius. These results provided a theoretical basis and a new perspective for further understanding the R2R3-MYB gene family and the biosynthesis mechanism of secondary metabolites in P. quinquefolius.