Chalcone Synthase Gene Expression Research Articles

Simultaneous Application of Several Exogenous dsRNAs for the Regulation of Anthocyanin Biosynthesis in Arabidopsis thaliana.

Plant surface treatment with double-stranded RNAs (dsRNAs) has gained recognition as a promising method for inducing gene silencing and combating plant pathogens. However, the regulation of endogenous plant genes by external dsRNAs has not been sufficiently investigated. Also, the effect of the simultaneous application of multiple gene-specific dsRNAs has not been analyzed. The aim of this study was to exogenously target five genes in Arabidopsis thaliana, namely, three transcription factor genes (AtCPC, AtMybL2, AtANAC032), a calmodulin-binding protein gene (AtCBP60g), and an anthocyanidin reductase gene (AtBAN), which are known as negative regulators of anthocyanin accumulation. Exogenous dsRNAs encoding these genes were applied to the leaf surface of A. thaliana either individually or in mixtures. The mRNA levels of the five targets were analyzed using qRT-PCR, and anthocyanin content was evaluated through HPLC-MS. The results demonstrated significant downregulation of all five target genes by the exogenous dsRNAs, resulting in enhanced expression of chalcone synthase (AtCHS) gene and increased anthocyanin content. The simultaneous foliar application of the five dsRNAs proved to be more efficient in activating anthocyanin accumulation compared to the application of individual dsRNAs. These findings hold considerable importance in plant biotechnology and gene function studies.

UV-C radiation promoted flavonoid synthesis during early healing in potato tuber wounds with the possible involvement of ABA and related transcription factor regulation

UV-C radiation has been widely proven to promote flavonoid synthesis in fruit and vegetables as an environmentally friendly treatment. However, it is unknown whether UV-C promotes flavonoid synthesis in potato tuber wounds during early healing and its possible regulatory mechanism. In this study, UV-C radiation increased the gene expression and activities of zeaxanthin epoxidase (ZEP) and 9-cis-epoxycarotenoid dioxygenase (NCED), and increased ABA levels. Meanwhile, UV-C upregulated the expression levels of StPYR1, StPYR2, StPYR3, StPP2C, SnRK2.1 and StABF, and promoted ABA signaling in tuber wounds. In addition, UV-C upregulated the expression levels of related transcription factors, including StMYB12, StMYB308, StbHLH93 and StbHLH143. Furthermore, UV-C regulated the gene expression and activities of chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H) and flavonol synthase (FLS), and promoted the accumulation and synthesis of flavonoids in tuber wounds. It is suggested that ABA and related transcription factors, including StMYB12, StMYB308, StbHLH93 and StbHLH143, may be involved in the regulation of UV-C radiation-driven flavonoid synthesis in potato tuber wounds during early healing.

Green silver nanoparticles display protection against Clavibacter michiganensis subsp. michiganensis in tomato plants (Solanum lycopersicum L.)

The quarantined bacterium Clavibacter michiganensis subsp. michiganensis (Cmm) causes significant losses on tomato plants worldwide, therefore efforts to reduce its damage are imperative. The alternatives offered by nanotechnology in the near future to be applied for the control of Cmm should be studied. Hence, this study aimed to determine the antibacterial activity of silver nanoparticles (AgNPs) biosynthesized on Moringa (Mo) leaves against Cmm in tomato plants (Solanum lycopersicum L.) and the possible protective mechanisms associated. UV–vis, TEM and FTIR, elucidated some structural and physicochemical characteristics of biosynthesized AgNPs. The preventive and curative effect of Mo extract and Mo-AgNPs at 50 ppm against Cmm in tomato plants was evaluated. Cmm was inoculated in the stems of tomato plants with 1 × 109 UFC/mL. Biometric parameters, disease severity, PAL, CAT, SOD activities, H2O2 levels, as well as chalcone synthase and pr1a gene expression were measured in greenhouse during 29 days. The UV–vis spectrum revealed the maximum absorption at 330 nm. Mo-AgNPs (32 nm; quasi-spherical shape) exhibited antibacterial potential against Cmm decreasing the disease severity by 86.29 % at 29 days after the treatments were applied. Besides, the Mo extract decreased the disease severity in 72 %, both compared to the control, being these two treatments the most promising for controlling Cmm. The Mo extract in preventive and curative treatments had the highest numbers of leaves, 33.31 %. The enzymatic activity exhibited no discernible pattern when comparing healthy and diseased plants, measured 29 days after the confrontations. Gene expression suggested a role of SAR pathway in the protective treatment by Mo Ag-NPs. In conclusion, the application of AgNPs derived from Mo leaf extracts effectively reduces the disease severity caused by Cmm on tomato plants under greenhouse conditions.

Enhanced Antioxidant and Anticancer Potential of Artemisia carvifolia Buch Transformed with rol A Gene.

Secondary metabolites have been shown to possess a range of biological functions. Flavonoids, due to their ability to scavenge ROS, are famous antioxidants. The plants of Artemisia species are rich sources of flavonoids; however, the amount of these metabolites is less. In the current study, the flavonoid content was detected and then enhanced by genetically modifying the Artemisia carvifolia Buch with Agrobacterium tumefaciens strain GV3101 carrying rol A gene. The transformation of rol A gene was confirmed with PCR and the gene copy number was confirmed by Southern blot analysis. The HPLC analysis revealed the presence of catechin (3.19 ug/mg DW) and geutisic acid (2.22 ug/mg DW) in transformed plants, unlike wild-type plants. In transformed plants, all detected flavonoids (vanillic acid, rutin, catechine, gallic acid, syringic acid, caffeic acid, coumaric acid, geutisic acid, ferulic acid, and cinnamic acid) were increased up to several folds. Real-time qPCR revealed the higher expression levels of the genes for flavonoid biosynthesis enzymes phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) in plants transformed with rol A genes, as the expression levels were increased up to 9-20-fold and 2-6-fold, respectively. The rol A transgenic lines T3 and T5 carrying two copies of rol A gene, particularly showed higher expression of both PAL and CHS gene, with the highest expression in T3 line. The transgenic lines demonstrated an average increase of 1.4-fold in the total phenolic content and 1-2-fold in the total flavonoid content as compared to wild-type plants. Total antioxidant capacity and total reducing power were increased up to an average of 1-2-fold and 1.5-2-fold respectively, along with increased free radical scavenging ability. Furthermore, the rol A gene transgenics were found to have much greater cytotoxic capacity than the A. carvifolia wild-type plant against the MCF7, HeLA, and HePG2 cancer cell lines. Current findings show that the rol A gene effectively increases the flavonoid content of A. carvifolia Buch, boosting the plant's capacity as an antioxidant and an anticancer. This is the first-ever report, demonstrating the genetic transformation of Artemisia carvifolia Buch with rol A gene.

Cloning, expression and activity analysises of chalcone synthase genes in Carthamus tinctorius

ObjectiveFlavonoids are the bioactive compounds in safflower (Carthamus tinctorius), in which chalcone synthase (CHS) is the first limiting enzyme. However, it is unclear that which chalcone synthase genes (CHSs) are participated in flavonoids biosynthesis in C. tinctorius. In this study, the CHSs in the molecular characterization and enzyme activities were investigated. MethodsPutative chalcone biosynthase genes were screened by the full-length transcriptome sequences data in C. tinctorius. Chalcone biosynthase genes in C. tinctorius (CtCHSs) were cloned from cDNA of flowers of C. tinctorius. The cloned gene sequences were analyzed by bioinformatics, and their expression patterns were analyzed by real-time PCR (RT-PCR). The protein of CtCHS in the development of flowers was detected by polyclonal antibody Western blot. A recombinant vector of CtCHS was constructed. The CtCHS recombinant protein was induced and purified to detect the enzyme reaction (catalyzing the reaction of p-coumaryl-CoA and malonyl-CoA to produce naringin chalcone). The reaction product was detected by HPLC and LC-MS. ResultsTwo full-length CtCHS genes were successfully cloned from the flowers of safflower (CtCHS1 and CtCHS3), with gene lengths of 1525 bp and 1358 bp, respectively. RT-PCR analysis showed that both genes were highly expressed in the flowers, but the expression of CtCHS1 was higher than that of CtCHS3 at each developmental stage of the flowers. WB analysis showed that only CtCHS1 protein could be detected at each developmental stage of the flowers. HPLC and LC-MS analyses showed that CtCHS1 could catalyze the conversion of p-coumaryl-CoA and malonyl-CoA substrates to naringin chalcone. ConclusionCtCHS1 is involved in the biosynthesis of naringin chalcone in safflower.

Integrated metabolomics and transcriptomics analysis of roots of Bupleurum chinense and B. scorzonerifolium, two sources of medicinal Chaihu

Radix Bupleuri (Chaihu in Chinese) is a traditional Chinese medicine commonly used to treat colds and fevers. The root metabolome and transcriptome of two cultivars of B. chinense (BCYC and BCZC) and one of B. scorzonerifolium (BSHC) were determined and analyzed. Compared with BSHC, 135 and 194 differential metabolites were identified in BCYC and BCZC, respectively, which were mainly fatty acyls, organooxygen metabolites. A total of 163 differential metabolites were obtained between BCYC and BCZC, including phenolic acids and lipids. Compared with BSHC, 6557 and 5621 differential expression genes (DEGs) were found in BCYC and BSHC, respectively, which were annotated into biosynthesis of unsaturated fatty acid and fatty acid metabolism. A total of 4,880 DEGs existed between the two cultivars of B. chinense. The abundance of flavonoids in B. scorzonerifolium was higher than that of B. chinense, with the latter having higher saikosaponin A and saikosaponin D than the former. Pinobanksin was the most major flavonoid which differ between the two cultivars of B. chinense. The expression of chalcone synthase gene was dramatically differential, which had a positive correlation with the biosynthesis of pinobanksin. The present study laid a foundation for further research on biosynthesis of flavonoids and terpenoids of Bupleurum L.

Inoculation of Pochonia chlamydosporia triggers a defense response in tomato roots, affecting parasitism by Meloidogyne javanica

Pochonia chlamydosporia is a soil-dwelling fungus and biological control agent of nematodes, active ingredient in commercial bionematicides. The fungus is also endophytically associated with the roots of several plant species, promoting their growth and inducing systemic resistance. In this study, different pathways and tomato defense metabolites were studied to identify mechanisms induced by P. chlamydosporia that contribute to the control of Meloidogyne javanica, at early and late developmental stages. Some defense responses activated by the fungus appeared related to the nematode life cycle. Among the evaluated biochemical analysis, root colonization of P. chlamydosporia showed an increase in the concentration of phenolic compounds, such as chlorogenic acid. In addition, the expression of some host plant genes was also modified. The interaction of the fungus with roots parasitized by M. javanica resulted in the highest expression of Phenylalanine Ammonia-Lyase (PAL), Chalcone synthase (LECHS 2), and Protease Inhibitor (PI1) genes at 24 days post-inoculation. At the second sampling time (44 days), there was an increase in the expression of the Respiratory Burst Oxidase Homolog (RBOH) gene. Fungus reduced the expression of the ACC-oxidase and Pathogenesis-Related Proteins 1 (PR-1) genes in roots. Moreover, P. chlamydosporia inoculation changed metabolites and phytohormone profiles of the gall formed by M. javanica. Plant defense response appeared to involve the jasmonic acid and phytosphingosine cascades. With this analysis, it was possible to propose new molecular mechanisms induced by the fungus that contribute to the control of M. javanica.

Exogenous Application of Aloe vera Leaf Extract Improves Silybin Content in Silybum marianum L. by Up-Regulating Chalcone Synthase Gene

Biotic elicitors such as Aloe vera extract (ALE) have been shown to stimulate growth and modify the bioactive composition of various plant species. ALE has a unique mixture of nutrients that support plant production and growth. In this study, the bio-stimulative effects of ALE foliar spray on plant production and growth, silybin levels, and chalcone synthase gene expression in Silybum marianum were examined. The findings indicated that foliar spray of all the ALE concentrations under study increased plant growth and yield. Additionally, by raising the silybin level of the plant extract, ALE increased the therapeutic value of S. marianum. Further, the activation of the chalcone synthase gene by ALE was analyzed by gene expression research. S. marianum’s growth and production were improved by the application of 60 mL/L ALE, while the silybin level and the chalcone synthase gene expression levels were improved by the application of 40 mL/L ALE. In addition, methanolic fruit extract that contained a higher silybin content also demonstrated a higher anti-microbial activity against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

Molecular characterization of polyphenol oxidase between small and large leaf tea cultivars

Tea is a widely consumed beverage prepared using the fresh leaves of Camellia sinensis L. Tea plants are classified into small- and large-leaf varieties. Polyphenol oxidase (PPO), a crucial enzyme in tea manufacturing, catalyzes essential phenolic metabolites into different derivatives. To compare the molecular characteristics of CsPPO between cultivars, we cloned the full-length sequence of CsPPO cDNA from four representative tea cultivars in Taiwan. Amino acid sequence alignment analyses indicated that CsPPO is highly conserved. PPO exhibited similar enzymatic activity in different tea cultivars. Quantitative real-time polymerase chain reaction revealed no significant differences in the CsPPO transcript level between the small- and large-leaf varieties. However, tea harvested in summer and from low-altitude areas had a higher CsPPO transcript level than that harvested in winter and from high-altitude areas. Regulation of CsPPO by temperature was more significant in the small-leaf variety than in the large-leaf variety. The content of flavonoids and the expression of chalcone synthase, anthocyanidin synthase, and anthocyanidin reductase genes involved in the tea flavonoid biosynthesis pathway were higher in the large-leaf than in the small-leaf varieties, suggesting that the large-leaf variety had a higher antioxidative capacity than did the small-leaf variety. Our study compared the molecular properties of CsPPO between two tea varieties and clarified the physiological role of PPO in tea.

UV-B- triggered H2O2 production mediates isoflavones synthesis in germinated soybean.

In this study, the functions of Hydrogen peroxide (H2O2) on the synthesis of isoflavones in germinated soybean under UV-B radiation were investigated. Results showed that the activity, gene, and protein expression of NADPH oxidase were up-regulated by 1.46, 6.92, and 1.34 times with UV-B radiation, while endogenous H2O2 content was also significantly increased. UV-B radiation and exogenous H2O2 treatment significantly increased the activities, gene and protein expression of phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), and isoflavone synthase (IFS) involved in isoflavones synthesis, and there was a synergistic effect with combining treatment. However, these up-regulation effects were suppressed by the supplementary diphenylene iodonium (DPI), which is the inhibitor of NADPH oxidase. Interestingly, the inhibition effect was largely reversed by exogenous H2O2, indicating that H2O2 was indispensable in regulating the isoflavones synthesis in germinated soybeans under UV-B radiation. Overall, H2O2 is an essential signaling molecule, mediating UV-B-induced isoflavone accumulation.

Newly designed CHS genic primers for four Zingiberaceae species (Alpinia mutica, Alpinia rafflesiana, Hornstedtia leonurus and Scaphochlamys kunstleri)

Flavonoids are secondary metabolites. To date, 2000 naturally occurring flavonoids are known present in plants. These diverse groups of antioxidants are abundant in rhizomes and leaves of Zingiberaceae species. Flavonoids are expressed by many genes. The most studied is chalcone synthase (CHS) gene. However, no study has been performed to study CHS gene in four endemic and pharmacological known Zingiberaceae species: Alpinia mutica, Alpinia rafflesiana, Hornstedtia leonurus and Scaphochlamys kunstleri. Furthermore, A. rafflesiana and S. kunstleri are threatened species. Thus, this study aimed to develop new CHS primers for these selected species. A total of 43 sequences of CHS genes belong to Zingiberaceae and Costaceae were retrieved from the NCBI database. Then, BLASTN was used to check sequence similarities of the retrieved CHS sequences to these four studied species, other Zingiberaceae and Costaceae. In follow, all redundant sequences were excluded and 15 sequences were saved as the final dataset. These 15 sequences were used to design genic primers using Primer3 software and in-silico analysed using OligoAnalyzer™ Tool. This study had successfully designed 12 new CHS genic primers. All the primers can be used for future studies to determine the presence and expression of CHS gene in these four species.

Transcriptomic and Coexpression Network Analyses Revealed Pine Chalcone Synthase Genes Associated with Pine Wood Nematode Infection.

Pine wood nematode (PWN) causes serious diseases in conifers, especially pine species. To investigate the transcriptomic profiles of genes involved in pine-PWN interactions, two different pine species, namely, Pinus thunbergii and P. massoniana, were selected for this study. Weighted gene coexpression network analysis (WGCNA) was used to determine the relationship between changes in gene expression and the PWN population after PWN infection. PWN infection negatively affects the expression of most genes in pine trees, including plant defense-related genes such as genes related to plant hormone signal transduction, plant-pathogen interactions, and the MAPK signaling pathway in plants. However, the expression of chalcone synthase genes and their related genes were proportional to the changes in nematode populations, and chalcone synthase genes were dominant within the coexpression module enriched by genes highly correlated with the nematode population. Many genes that were closely related to chalcone synthase genes in the module were related to flavonoid biosynthesis, flavone and flavonol biosynthesis, and phenylpropanoid biosynthesis. Pine trees could actively adjust their defense strategies in response to changes in the number of invasive PWNs, but the sustained expression of chalcone synthase genes should play an important role in the inhibition of PWN infection.

Secondary metabolites and related genes in Vitis vinifera L. cv. Tempranillo grapes as influenced by ultraviolet radiation and berry development.

The effects of UV radiation on Vitis vinifera cv Tempranillo grapes were studied under field conditions as influenced by ultraviolet (UV) band (UV-A and UV-B), UV-B level (ambient vs enhanced), grape phenological stage (pea-size, veraison, and harvest), grape component (skin, flesh, and seeds), and fraction from which phenolic UV-absorbing compounds (UVACs) were extracted (soluble vs insoluble). Ambient UV-B levels caused stronger effects than ambient UV-A. These effects included increases in flavonol contents (particularly quercetins and kaempferols), the expression of flavonol synthase and chalcone synthase genes (VvFLS4 and VvCHS1), and grape weight and size. In addition, the contents of flavanols and hydroxycinnamic acids increased under UV-B radiation at pea-size stage. All these compounds play physiological roles as antioxidants and UV screens. Synergic effects between UV-B and UV-A were observed. The responses of anthocyanins, stilbenes, and volatile compounds to UV were diffuse or nonexistent. Enhanced UV-B led to rather subtle changes in comparison with ambient UV-B, but differences between both treatments could be demonstrated by multivariate analysis. Pea-size and harvest were the phenological stages where the most significant responses to UV were found, while the skin was the most UV-responsive grape component. Soluble phenolic compounds were much more UV-responsive than insoluble compounds. In conclusion, UV radiation was essential for the induction of specific grape phenolic and volatile compounds. Given the physiological roles of these compounds, as well as their contribution to grape and wine quality, and their potential use as nutraceuticals, our results may have implications on the artificial manipulation of UV radiation.

Physiological and molecular responses of black cumin (Nigella sativa L.) seedlings to silver nanoparticles

Due to their anti-bacterial and anti-fungal properties, silver (Ag) nanoparticles (AgNPs) are increasingly being used in consumer products. In this study, the effects of applying different concentrations of AgNPs (0, 2.5, 5, 10, 20, 40 and 80 mg L−1) on the growth, leaf concentrations of Ag, micro and macro-elements, leaf concentrations of malondialdehyde (MDA) and H2O2, total antioxidant activity and activity of antioxidant enzymes in leaf extracts and leaf expression of phenylalanine ammonia-lyase (PAL) and chalcone synthase (GSH) genes were investigated in black cumin (Nigella sativa) seedlings. Results showed that AgNPs treatments led to increases in Ag concentrations in leaves and roots, with the accumulation in roots being slightly higher than leaves. AgNPs treatments at concentrations over 20 mg L−1 reduced growth, biomass production and accumulation of macro- (P, Mg and Ca) and micro-elements (Zn, Cu, Mn and B) and increased total antioxidant activity and MDA and H2O2 contents. Application of AgNPs also increased the activity of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) and catalase (CAT) in leaf extracts when compared to the controls. The activity and expression of PAL and CHS enzymes also increased significantly with AgNPs treatment. Results indicate that the oxidative stress induced by AgNPs in black cumin plants is counteracted by increases in the activity of antioxidant systems and the expression and activity of PAL and CHS enzymes.

Quercetin alleviates seed germination and growth inhibition in Apocynum venetum and Apocynum pictum under mannitol-induced osmotic stress

Quercetin is one of the main flavonoids in the human diet and mainly found in different plant tissues, including seeds, flowers, leaves, stems, and roots. However, its biological function in plant tissues, especially in seeds, is unknown. In this study, the seed germination and subsequent seedling growth of Apocynum pictum and A. venetum under osmotic stress (400 mmol L−1 mannitol) supplemented with 5 μmol L−1 quercetin were evaluated after 7, 14, and 21 days of germination. Results showed that quercetin improved the germination percentage and seed vigor, as indicated by the higher germination energy, shoot length, root length, dry weight, fresh weight, and chlorophyll content in A. pictum and A. venetum seedlings under the mannitol compared with those under the mannitol alone. Quercetin decreased H2O2 and O2− production and cell membrane damage, and mostly increased the gene expression of superoxide dismutase, peroxidase, catalase, chalcone synthase and flavonol synthase in A. pictum and A. venetum seedlings under the mannitol compared with those under the mannitol alone. In addition, the germination energy of A. pictum was 21.57% higher than that of A. venetum, and the gene expression of key enzymes in quercetin biosynthesis in A. pictum was mostly higher than that in A. venetum after 1 and 7 days of germination. These results indicated that quercetin was an effective anti-osmotic agent that alleviated the adverse effect of mannitol-induced osmotic stress on seed germination and seed vigor, and A. pictum seeds were more osmotic resistant than A. venetum seeds.

Quantification of polyphenolic compounds and relative gene expression studies of phenylpropanoid pathway in apple (Malus domestica Borkh) in response to Venturia inaequalis infection.

Apple (Malus domestica Borkh) is rich in phenolic compounds, which may enhance resistance to scab disease caused by Venturia inaequalis. In present study, apple cv. Golden Delicious was used for estimation of total phenols, flavonoids and quantification of six individual phenolic compounds. between control vs inoculated samples at different inoculation stages. The relative gene expression of phenylalanine ammonia lyase, chalcone synthase and flavanone 3 hydroxylase increased and polyphenolic compounds were constitutively upregulated at different post-inoculation stages. Data suggest that synthesis and accumulation of polyphenols is closely related with disease resistance against Venturia inaequalis. This study may play a vital role in understanding and finding out the governing mechanisms of scab resistance.

Differential Response to Water Deficit in Chili Pepper (Capsicum annuum L.) Growing in Two Types of Soil Under Different Irrigation Regimes

Chili pepper (Capsicum spp.) is one of the most economically important horticultural crops in the world; its production for the food and pharmaceutical industries has been increasing worldwide. The economic importance of this crop is due, in part, to the nutraceutical properties derived from its secondary metabolism. Drought is the main environmental factor that affects crop production. Nevertheless, studies involving water deficit have considered short-term responses to sharp water deficit rather than long-term acclimation processes through moderate and gradually increasing water deficits, which omitted the dynamics and profile of the secondary metabolism that are part of the plant’s defence system against this stress factor. The present study aimed to identify the different mechanisms that chili pepper plants use to cope with drought stress using a progressive decrease and increase of water availability, conditions that commonly occur for crops in open fields. Four treatments were applied as follows: gradual water deficit (GWD), initial waterlogging with gradual water deficit (IWGD), sudden water deficit with gradual recovery (SWDR), and no deficit of water (NDW). These conditions should represent a more real situation similar to that faced by plants in the agricultural environment. In order to evaluate the response mechanisms associated with these water deficits, changes in phenological variables, proline accumulation, and the gene expression of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), peroxidase (POD), and superoxide dismutase (SOD) were measured in chili pepper plants growing on land under different irrigation regimes in two contrasting soil types in areas where chili pepper plants are cultivated in central Mexico. The variables evaluated showed a differentiated response of the mechanisms in plants growing under different levels of water deficit. Given the differential response observed for the gene expression and morphological and biochemical variables studied in chili pepper plants against different water regimes, in this work, this may have implications for more efficient use of water in crops with high nutraceutical content, in addition to prospects for using products derived from secondary metabolism in the pharmaceutical industry.

GABA mediates NO/cGMP/GSK-3-induced isoflavone accumulation in soybean sprouts

The effects of glycogen synthase kinase-3 (GSK-3) on nitric oxide (NO)/guanosine 3′,5′-cyclic monophosphate (cGMP)-activated γ-aminobutiric acid (GABA) accumulation and the role of GABA in isoflavone biosynthesis in response to UV-B exposure in soybean sprouts were investigated. The sprouts were sprayed using donors and inhibitors of cGMP and NO as well as inhibitors of GSK-3 and GABA. It turned out that GSK-3, as a second messenger, mediated NO/cGMP/PKG-induced GABA accumulation by activating diamine oxidase (DAO) under UV-B treatment. GABA mediated NO/cGMP/PKG/GSK-3-stimulated the increment of gene and protein expression and activity of chalcone synthase (CHS) and isoflavone synthase (IFS), and consequently induced the elevation in isoflavone content. Overall, GABA mediates NO/cGMP/PKG/GSK-3-stimulated isoflavone production in response to UV-B exposure in soybean sprouts.

Exogenous application of phytosulfokine α (PSKα) delays yellowing and preserves nutritional quality of broccoli florets during cold storage

In this study, we tested the exogenous application of phytosulfokine α (PSKα) for delaying the yellowing of broccoli florets during cold storage. Our results showed that the lower yellowing in broccoli florets treated with 150 nM PSKα was probably due to the higher endogenous accumulation of PSKα, leading to the endogenous accumulation of guanosine 3′, 5′-cyclic monophosphate (cGMP). Besides, broccoli florets treated with 150 nM PSKα exhibited a higher accumulation of phenols and flavonoids by triggering gene expression and activities of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS). Moreover, the higher expression of L‐galactotno‐1,4‐lactone dehydrogenase (GLDH) gene and the lower expression of ascorbic acid oxidase (AAO) gene in broccoli florets treated with 150 nM PSKα may be the reasons for the higher accumulation of ascorbic acid. In conclusion, the exogenous application of PSKα is a promising strategy in delaying the yellowing and preserving the nutritional quality of broccoli florets during cold storage.

Agrobacterium rhizogenes-mediated transformation enhances the antioxidant potential of Artemisia tilesii Ledeb.

Plants belonging to the genus Artemisia L. have been used for medicinal purposes since ancient times. These aromatic plants produce and accumulate a wide range of potent secondary metabolites, many of which have shown antioxidant, antiparasitic, antimicrobial, anti-inflammatory, and even anticancer activities. Enhanced biosynthesis of these compounds is a prerequisite for comprehensive studies of their therapeutic properties and cost-efficient use. Transformation of plants with Agrobacterium rhizogenes native root locus (rol) genes is a promising approach to increase the biosynthesis of plant secondary metabolites. The aim of the present study was to evaluate the effects of A. rhizogenes-mediated transformation on the flavonoid contents in hairy roots of medicinal herb A. tilesii Ledeb. Transgenic A. tilesii hairy root lines were analyzed for stable integration of the rolB and rolC transgenes into the plant genome, total flavonoid contents, antioxidant activities of extracts, and the spatiotemporal expression of two flavonoid biosynthetic genes, phenylalanine ammonialyase (PAL) and chalcone synthase (CHS). The flavonoid contents of A. tilesii directly correlated with the antiradical activity and reducing power of their respective lines, with the greatest antioxidant activity found in the plants with the highest level of total flavonoids. Furthermore, all hairy root lines demonstrated altered expression of plant native PAL and CHS genes. Most importantly, A. rhizogenes-mediated transformation enhanced the biosynthesis of natural antioxidants in A. tilesii, producing almost twice the amount of flavonoids than controls. These findings provide an opportunity for the identification of the bioactive molecules in A. tilesii extracts and their potential health benefits.