Accumulation Of Phenylpropanoids Research Articles

How lignin biosynthesis responds to nitrogen in plants: ascoping review.

Nitrogen (N) plays a critical role in the functioning of key amino acids and synthetic enzymes responsible for the various stages of lignin biosynthesis. However, the precise mechanisms through which N influences lignin biosynthesis have not been fully elucidated. This scoping review explores how lignin biosynthesis responds to N in plants. A systematic search of the literature in several databases was conducted using relevant keywords. Only 44 of the 1842 selected studies contained a range of plant species, experimental conditions, and research approaches. Lignin content, structure, and biosynthetic pathways in response to N are discussed, and possible response mechanisms of lignin under low N are proposed. Among the selected studies, 64.52% of the studies reter to lignin content found a negative correlation between N availability and lignin content. Usually, high N decreases the lignin content, delays cell lignification, increases p-hydroxyphenyl propane (H) monomer content, and regulates lignin synthesis through the expression of key genes (PAL, 4CL, CCR, CAD, COMT, LAC, and POD) encoding miRNAs and transcription factors (e.g., MYB, bHLH). N deficiency enhances lignin synthesis through the accumulation of phenylpropanoids, phenolics, and soluble carbohydrates, and indirect changes in phytohormones, secondary metabolites, etc. This review provides new insights and important references for future studies on the regulation of lignin biosynthesis.

Effect of <i>Meloidogyne incognita</i> infection on the accumulation of phenolic compounds in plants of the genus Mint (Mentha L.)

The purpose of the research is to compare the accumulation of phenolic compounds of different species and varieties of mint, zoned in Central Russia against the background of plant infection by Meloidogyne incognita.Materials and methods. Plants were grown from cuttings in a growing experiment in open ground. Mentha × piperita L. (varieties: Tik-Tak, Orange, Minneola, Mojito, Mitchum, Chocolate), M. spicata L. (varieties Morocco, Crispa) and M. longifolia L. (Longifolia) were taken for the study. A month later, the rooted plants were infected at the rate of 1000 sp. infective larvae of M. incognita per plant. After 8 weeks leaves were fixed in ethanol. The total content of phenolic compounds (PC), phenylpropanoids, flavonoids and catechins was studied using a spectrophotometer. The determination of the total content of PС was carried out using the Folin-Cecolte reagent with measurement at 725 nm, phenylpropanoids – by direct measurement of optical density at 330 nm, flavonoids – by reaction with aluminum chloride at 415 nm, the total content of flavans (catechins - flavan-3-ols), their oligomeric forms – proanthocyanidins, as well as leukoanthocyanidins were assessed by reaction with vanillin at 500 nm.Results and discussion. It has been shown that the accumulation of phenols is related to the species of plants. The varieties Mentha × piperita L. in most cases contained more phenols than M. spicata L. and M. longifolia L. A significant number of PC was noted in the violet-colored varieties Mitchum, Chocolate and Orange. The total content of PC almost completely correlates with the content of their precursors – phenylpropanoids. In terms of the content of flavonoids, the Mitchum variety stands out noticeably, and in terms of the content of catechins, the Orange variety stands out. Nematode infection in most varieties causes a noticeable increase in the total accumulation of soluble PC, phenylpropanoids and flavans, but leads to a decrease in the content of flavonoids.

Methyl jasmonate improves resistance in scab-susceptible Red Delicious apple by altering ROS homeostasis and enhancing phenylpropanoid biosynthesis

Apple (Malus domestica) is an economically important rosaceous fruit crop grown at temperate climate zones. Nevertheless, its production is severely affected by scab disease caused by the ascomycetous fungus Venturia inaequalis (VI). Methyl jasmonate (MeJA) is a stress induced plant hormone, shown to induce resistance against wide range of pathogens. The current study investigated the role of MeJA in promoting scab tolerance in susceptible apple varieties through exogenous application of optimized (100 μM) MeJA concentration, followed by VI infection. According to our analysis, applying MeJA exogenously onto leaf surfaces resulted in increased membrane stability and decreased malondialdehyde levels in Red Delicious, suggesting that MeJA is capable of protecting tissues against oxidative damage through its role in restoring membrane stability. In addition, the changes in the levels of key antioxidative enzymes and reactive oxygen species (ROS) showed that exogenous MeJA maintains ROS homeostasis as well. Higher phenylalanine ammonia-lyase activity and increased accumulation of phenylpropanoids in MeJA-treated VI-infected plants indicated the MeJA reprogrammed phenylpropanoid biosynthesis pathway for scab tolerance. Our study of scab tolerance in apples induced by MeJA provides new insights into its physiological and biochemical mechanisms.

Comparative analyses reveal a phenylalanine ammonia lyase dependent and salicylic acid mediated host resistance in Zingiber zerumbet against the necrotrophic soft rot pathogen Pythium myriotylum

Little is known about the molecular basis of host defense in resistant wild species Zingiber zerumbet (L.) Smith against the soil-borne, necrotrophic oomycete pathogen Pythium myriotylum Drechsler, which causes the devastating soft rot disease in the spice crop ginger (Zingiber officinale Roscoe). We investigated the pattern of host defense between Z. zerumbet and ginger in response to P. myriotylum inoculation. Analysis of gene expression microarray data revealed enrichment of phenylpropanoid biosynthetic genes, particularly lignin biosynthesis genes, in pathogen-inoculated Z. zerumbet compared to ginger. RT-qPCR analysis showed the robust activation of phenylpropanoid biosynthesis genes in Z. zerumbet, including the core genes PAL, C4H, 4CL, and the monolignol biosynthesis and polymerization genes such as CCR, CAD, C3H, CCoAOMT, F5H, COMT, and LAC. Additionally, Z. zerumbet exhibited the accumulation of the phenolic acids including p-coumaric acid, sinapic acid, and ferulic acid that are characteristic of the cell walls of commelinoid monocots like Zingiberaceae and are involved in cell wall strengthening by cross linking with lignin. Z. zerumbet also had higher total lignin and total phenolics content compared to pathogen-inoculated ginger. Phloroglucinol staining revealed the enhanced fortification of cell walls in Z. zerumbet, specifically in xylem vessels and surrounding cells. The trypan blue staining indicated inhibition of pathogen growth in Z. zerumbet at the first leaf whorl, while ginger showed complete colonization of the pith within 36 h post inoculation (hpi). Accumulation of salicylic acid (SA) and induction of SA regulator NPR1 and the signaling marker PR1 were observed in Z. zerumbet. Silencing of PAL in Z. zerumbet through VIGS suppressed downstream genes, leading to reduced phenylpropanoid accumulation and SA level, resulting in the susceptibility of plants to P. myriotylum. These findings highlight the essential role of PAL-dependent mechanisms in resistance against P. myriotylum in Z. zerumbet. Moreover, our results suggest an unconventional role for SA in mediating host resistance against a necrotroph. Targeting the phenylpropanoid pathway could be a promising strategy for the effective management of P. myriotylum in ginger.

PSEUDO-ETIOLATION IN LIGHT proteins reduce greening by binding GLK transcription factors.

Knocking out genes encoding proteins that downregulate the accumulation of pigments may lead to increases in crop quality and yield. PSEUDO-ETIOLATION IN LIGHT 1 (PEL1) downregulates the accumulation of carotenoids in carrot and chlorophyll in Arabidopsis and rice and may inhibit GOLDEN 2-LIKE (GLK) transcription factors. PEL1 belongs to a previously unstudied gene family found only in plants. We used CRISPR/Cas9 technology to knock out each member of the 4-member PEL gene family and both GLK genes in Arabidopsis. In pel mutants, chlorophyll levels were elevated in seedlings; after flowering, chloroplasts increased in size, and anthocyanin levels increased. Although the chlorophyll-deficient phenotype of glk1 glk2 was epistatic to pel1 pel2 pel3 pel4 in most of our experiments, glk1 glk2 was not epistatic to pel1 pel2 pel3 pel4 for the accumulation of anthocyanins in most of our experiments. The pel alleles attenuated growth, altered the accumulation of nutrients in seeds, disrupted an abscisic acid-inducible inhibition of seedling growth response that promotes drought tolerance, and affected the expression of genes associated with diverse biological functions, such as stress responses, cell wall metabolism hormone responses, signaling, growth, and the accumulation of phenylpropanoids and pigments. We found that PEL proteins specifically bind 6 transcription factors that influence the accumulation of anthocyanins, GLK2, and the carboxy termini of GLK1 and Arabidopsis thaliana myeloblastosis oncogene homolog 4 (AtMYB4). Our data indicate that the PEL proteins influence the accumulation of chlorophyll and many other processes, possibly by inhibiting GLK transcription factors and via other mechanisms, and that multiple mechanisms downregulate chlorophyll content.

Transcriptomic and metabolomic analyses reveal the differential accumulation of phenylpropanoids and terpenoids in hemp autotetraploid and its diploid progenitor

BackgroundCannabis sativa, a dioecious plant that has been cultivated worldwide for thousands of years, is known for its secondary metabolites, especially cannabinoids, which possess several medicinal effects. In this study, we investigated the autopolyploidization effects on the biosynthesis and accumulation of these metabolites, transcriptomic and metabolomic analyses were performed to explore the gene expression and metabolic variations in industrial hemp autotetraploids and their diploid progenitors.ResultsThrough these analyses, we obtained 1,663 differentially expressed metabolites and 1,103 differentially expressed genes. Integrative analysis revealed that phenylpropanoid and terpenoid biosynthesis were regulated by polyploidization. No substantial differences were found in the cannabidiol or tetrahydrocannabinol content between tetraploids and diploids. Following polyploidization, some transcription factors, including nine bHLH and eight MYB transcription factors, affected the metabolic biosynthesis as regulators. Additionally, several pivotal catalytic genes, such as flavonol synthase/flavanone 3-hydroxylase, related to the phenylpropanoid metabolic pathway, were identified as being modulated by polyploidization.ConclusionsThis study enhances the overall understanding of the impact of autopolyploidization in C. sativa and the findings may encourage the application of polyploid breeding for increasing the content of important secondary metabolites in industrial hemp.

Production of Phenolic Compounds and Antioxidant Activity in Hairy Root Cultures of Salvia plebeia.

Salvia plebeia (Lamiaceae) is a medicinal plant containing diverse bioactive constituents that have biological properties. In this study, we determined the optimal conditions (media and auxin) for the hairy root culture of S. plebeia for the growth and accumulation of phenolic compounds and evaluated its antioxidant activities. Rosmarinic acid and five phenylpropanoids were detected using high-performance liquid chromatography. The hairy roots grown in 1/2 SH medium with 1 mg/L NAA had a high level of rosmarinic acid content. Hairy roots cultured in 1 mg/L NAA had the highest total content of five phenylpropanoids. Compared to wild-type roots grown in the field, hairy roots (NAA 1) expressed similar levels of rosmarinic acid but significantly enhanced phenylpropanoid accumulation. Furthermore, the total phenolic content and total flavonoid content of hairy roots (NAA 1) were 2.22 and 1.73 times higher than those of wild-type roots. In the results of DPPH, ABTS, and reducing power assays, the hairy roots (NAA 1) showed higher free radical scavenging effects and reduction potential than the wild-type roots. These results suggest that S. plebeia hairy roots cultured under optimal conditions, which exhibit enhanced phenolic compound accumulation and antioxidant activity, can potentially be used as sources of antioxidants.

Metabolomics Insight into the Variety-Mediated Responses to Aspergillus carbonarius Infection in Grapevine Berries.

Limited knowledge regarding the susceptibility of grape varieties to ochratoxin A (OTA)-producing fungi is available to date. This study aimed to investigate the susceptibility of different grape varieties to Aspergillus carbonarius concerning OTA contamination and modulation at the metabolome level. Six grape varieties were selected, sampled at early veraison and ripening, artificially inoculated with A. carbonarius, and incubated at two temperature regimes. Significant differences were observed across cultivars, with Barbera showing the highest incidence of moldy berries (around 30%), while Malvasia and Ortrugo showed the lowest incidence (about 2%). OTA contamination was the lowest in Ortrugo and Malvasia, and the highest in Croatina, although it was not significantly different from Barbera, Merlot, and Sauvignon Blanc. Fungal development and mycotoxin production changed with grape variety; the sugar content in berries could also have played a role. Unsupervised multivariate statistical analysis from metabolomic fingerprints highlighted cultivar-specific responses, although a more generalized response was observed by supervised OPLS-DA modeling. An accumulation of nitrogen-containing compounds (alkaloids and glucosinolates), phenylpropanoids, and terpenoids, in addition to phytoalexins, was observed in all samples. A broader modulation of the metabolome was observed in white grapes, which were less contaminated by OTA. Jasmonates and oxylipins were identified as critical upstream modulators in metabolomic profiles. A direct correlation between the plant defense machinery and OTA was not observed, but the information was acquired and can contribute to optimizing preventive actions.

Copper boosts the biostimulant activity of a vegetal-derived protein hydrolysate in basil: morpho-physiological and metabolomics insights.

In addition to be used as a plant protection agent, copper (Cu) is also an essential micronutrient for plant growth and development. The bioavailability of Cu in agricultural systems can be limited due to its specific physical-chemical characteristics, leading to imbalances in plant production. To address this issue, an experimental trial was conducted on Genovese basil (Ocimum basilicum L.) in protected conditions to comparatively evaluate the effects of a vegetable protein hydrolysate (VPH), free Cu and Cu complexed with peptides and amino acids of vegetal origin (Cu and Cu-VPH, respectively), and a combination of VPH and Cu-VPH (VPH+Cu-VPH). The study showed that the combined application of VPH+Cu-VPH led to a significant average increase of 16.3% in fresh yield compared to the untreated Control and Cu treatment. This finding was supported by an improved photosynthetic performance in ACO2 (+29%) and Fv/Fm (+7%). Furthermore, mineral analysis using ICP OES demonstrated that Cu and Cu-VPH treatments determined, on average, a 15.1-, 16.9-, and 1.9-fold increase in Cu in plant tissues compared to control, VPH, and VPH+Cu-VPH treatments, respectively. However, the VPH+Cu-VPH treatment induced the highest contents of the other analyzed ions, except for P. In particular, Mg, Mn, Ca, and Fe, which take part in the constitution of chlorophylls, water splitting system, and photosynthetic electron transport chain, increased by 23%, 21%, 25%, and 32% compared to respective controls. Indeed, this improved the photosynthetic efficiency and the carboxylation capacity of the plants, and consequently, the physiological and productive performance of Genovese basil, compared to all other treatments and control. Consistently, the untargeted metabolomics also pointed out a distinctive modulation of phytochemical signatures as a function of the treatment. An accumulation of alkaloids, terpenoids, and phenylpropanoids was observed following Cu treatment, suggesting an oxidative imbalance upon metal exposure. In contrast, a mitigation of oxidative stress was highlighted in Cu-VPH and VPH+Cu-VPH, where the treatments reduced stress-related metabolites. Overall, these results highlight an interaction between Cu and VPH, hence paving the way towards the combined use of Cu and biostimulants to optimize agronomic interventions.

Secondary metabolites in grapevine: crosstalk of transcriptional, metabolic and hormonal signals controlling stress defence responses in berries and vegetative organs.

Abiotic stresses, such as temperature, heat waves, water limitation, solar radiation and the increase in atmospheric CO2 concentration, significantly influence the accumulation of secondary metabolites in grapevine berries at different developmental stages, and in vegetative organs. Transcriptional reprogramming, miRNAs, epigenetic marks and hormonal crosstalk regulate the secondary metabolism of berries, mainly the accumulation of phenylpropanoids and of volatile organic compounds (VOCs). Currently, the biological mechanisms that control the plastic response of grapevine cultivars to environmental stress or that occur during berry ripening have been extensively studied in many worlds viticultural areas, in different cultivars and in vines grown under various agronomic managements. A novel frontier in the study of these mechanisms is the involvement of miRNAs whose target transcripts encode enzymes of the flavonoid biosynthetic pathway. Some miRNA-mediated regulatory cascades, post-transcriptionally control key MYB transcription factors, showing, for example, a role in influencing the anthocyanin accumulation in response to UV-B light during berry ripening. DNA methylation profiles partially affect the berry transcriptome plasticity of different grapevine cultivars, contributing to the modulation of berry qualitative traits. Numerous hormones (such as abscisic and jasmomic acids, strigolactones, gibberellins, auxins, cytokynins and ethylene) are involved in triggering the vine response to abiotic and biotic stress factors. Through specific signaling cascades, hormones mediate the accumulation of antioxidants that contribute to the quality of the berry and that intervene in the grapevine defense processes, highlighting that the grapevine response to stressors can be similar in different grapevine organs. The expression of genes responsible for hormone biosynthesis is largely modulated by stress conditions, thus resulting in the numeourous interactions between grapevine and the surrounding environment.

Egg-Associated Germs Induce Salicylate Defenses but Not Render Plant Against a Global Invasive Fruit Fly Effectively.

Germs associated with insect eggs can profoundly mediate interactions between host plants and herbivores, with the potential to coordinate plant physiological reactions with cascading effects on insect fitness. An experimental system was established including the oriental fruit fly (OFF, Bactrocera dorsalis) and tomato to examine the functions of egg-associated germs in mediating plant-herbivore interactions. OFF feeding resulted in significantly increased tannins, flavonoids, amino acids, and salicylic acid in the host tomato. These defensive responses of tomato were induced by the egg-associated germs, including Lactococcus sp., Brevundimonas sp., and Vagococcus sp. Tannins and flavonoids had no significant feedback effects on the pupal weight of OFF, while pupal biomass was significantly decreased by tannins and flavonoids in the germ-free treatment. Metabolome analysis showed that OFF mainly induced metabolic changes in carboxylic acid derivatives. Phenylalanine significantly induced downstream metabolic changes associated with phenylpropanoid accumulation. Finally, we conclude that the effects of egg-associated germs played an important role in facilitating OFF population adaptation and growth by mediating plant defenses, which provides a new paradigm for exploring the interaction of plant-pest and implementing effective pest biocontrol.

Global Metabolome of Palmer Amaranth (Amaranthus palmeri) Populations Highlights the Specificity and Inducibility of Phytochemical Responses to Abiotic Stress.

Commonalities in adaptive responses to abiotic stressors could contribute to the development of cross-resistance in weeds. The degree to which herbicide-induced changes in weeds parallel those induced by other abiotic stress remains unknown. We investigated the specificity of metabolic perturbations induced by glyphosate and drought across three glyphosate-resistant (GR) and two glyphosate-susceptible (GS) biotypes of Palmer amaranth (Amaranthus palmeri) using global metabolomics approaches. Compared to GS-biotypes, in the absence of stress, the GR-biotypes had a higher abundance of primary metabolites, including sugars, nonaromatic amino acids, and organic acids. However, despite having a higher 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene copy number that could upregulate the phenylpropanoid metabolism, the nonstressed GR-biotypes were less abundant in specialized (secondary) metabolites. Under glyphosate stress, 80% of metabolites, including shikimate, that accumulated in GS-biotypes also increased in the GR-biotypes. However, glyphosate triggered the preferential accumulation of glycosides of dihydroxylated and methoxylated flavanols with higher antioxidant potential, and ferulic acid derivatives, specifically in GR-biotypes. The disruption of the shikimate pathway and the accumulation of phenylpropanoids upon glyphosate exposure suggest that the stress response of GR-biotypes could be partly induced. This differential response was less evident in other phytochemical classes and under drought, highlighting that the phytochemical responses are stress-specific rather than biotype-specific.

Pimpinella pruatjan Molk: LC-MS/MS-QTFT Analysis of Bioactive Compounds from Decoction and Ethanol Extract of Aerial Parts.

Pimpinella pruatjan Molk is native to Java and well known as aphrodisiac in traditional medicine. A water-boiled extract of the plant has been used in the treatment of erectile dysfunction (ED). No study has been found on the phytochemical constituents and identification of corresponding biological activities in water and polar extract. This study is aimed to identify phytoconstituents of a decoction and ethanol extract from the aerial parts of P. pruatjan Molk. Liquid chromatography-tandem mass spectroscopy (LC-MS/MS) was used to analyze and predict the bioactive compounds in both extracts. LC-MS/MS revealed both extracts contained two important compounds: Luteolin-7-O-β-D glucopyranoside and Undulatoside A. Luteolin and Luteolin glucoside are also found in P.anisum L. Lutein 7-O glucoside was found in water extract, while more bioactive compounds, including populnin, 3,5-O-dicaffeoylquinic acid, quercetin-3'- O glucoside, methylophiopogononeone-A, kaempferol-7-O-α-L-arabinofuranoside, and 7-hydroxy-3,5,6,3',4'- pentamethoxyflavone, were found in ethanol extract. Accumulation of flavonoids, phenols, phenylpropanoids, alkaloids, and furanochromone in low quantities was observed in both extracts. This is the first report providing evidence justifying its use as a traditional medicine. Further investigation into the pharmacology mechanism of action is required.

Integrative transcriptomic, proteomic and metabolomic analysis reveals the dynamic regulation of secondary metabolism upon development of Prunella vulgaris L.

Prunella vulgaris L. (P. vulgaris, Labiatae) is a perennial medicinal and edible plant widely used in China, Korea, Japan and Europe. The reddish brown spica of P. vulgaris (Prunellae Spica), which is collected in summer, has been commonly used in traditional medicine and food industry, while it is also used with whole grass in Europe and Taiwan. To clarify the regulatory pathways and mechanism of quality formation in P. vulgaris, targeted metabolomic, transcriptomic, and proteomic analyses of Prunellae Spica samples from five consecutive developmental stages were carried out. The results showed that terpenoids were mainly synthesized in the maturity stage of Prunellae Spica, with the key enzymes and coding genes in downstream pathways being mainly expressed during ripening, while related enzymes in the upstream pathway showed the opposite pattern. Flavonoids mainly accumulated before ripening, with highly expressed pathway enzymes and coding genes. The accumulation of phenylpropanoids was relatively active throughout the development process. Rosmarinic acid (RA) and its synthetic intermediate products mainly accumulated via more active pathway enzymes and coding genes before ripening. The regulatory factors and metabolites related to RA synthesis were mainly enriched in phenylpropanoid biosynthesis, plant hormone signal transduction, plant pathogen interaction, oxidative phosphorylation, and endoplasmic reticulum protein processing pathways.

Improvement of Antioxidant Properties in Fruit from Two Blood and Blond Orange Cultivars by Postharvest Storage at Low Temperature.

Numerous studies have revealed the remarkable health-promoting activities of citrus fruits, all of them related to the accumulation of bioactive compounds, including vitamins and phytonutrients. Anthocyanins are characteristic flavonoids present in blood orange, which require low-temperature for their production. Storage at low-temperature of blood oranges has been proven to be a feasible postharvest strategy to increase anthocyanins in those countries with warm climates. To our knowledge, no studies comparing the effect of postharvest storage effect on phenylpropanoid accumulation in cultivars with and without anthocyanins production have been published. We have investigated the effect of postharvest cold storage in flavonoid accumulation in juice from Citrus sinensis L. Osbeck in two different oranges: Pera, a blond cultivar, and Moro, a blood one. Our findings indicate a different response to low-temperature of fruit from both cultivars at biochemical and molecular levels. Little changes were observed in Pera before and after storage, while a higher production of phenylpropanoids (3.3-fold higher) and flavonoids (1.4-fold higher), including a rise in anthocyanins from 1.3 ± 0.7 mg/L to 60.0 ± 9.4 mg/L was observed in Moro concurrent with an upregulation of the biosynthetic genes across the biosynthetic pathway. We show that postharvest storage enhances not only anthocyanins but also other flavonoids accumulation in blood oranges (but not in blond ones), further stimulating the interest in blood orange types in antioxidant-rich diets.

Chitosan thiamine nanoparticles intervene innate immunomodulation during Chickpea-Fusarium interaction.

The present study evaluated the effect of chitosan thiamine nanoparticles (TCNP) on the activation of defence responses in chickpea against stress caused by wilt pathogen, Fusarium oxysporum f. sp. ciceri (FOC), under greenhouse condition. A significant increase in enzymatic and non-enzymatic antioxidants was observed in the TCNP treated chickpea plants challenged with FOC compared to the untreated control. Histochemical staining showed high deposition of lignin in the vascular bundles of chickpea stem tissues in TCNP treated plants challenged with FOC. More than 90% protection against wilt pathogen was observed in TCNP treated chickpea plants challenged with FOC, under greenhouse condition. Higher accumulation of antioxidants and phenylpropanoids in TCNP treated challenged chickpea plants well correlates with resistance against wilt pathogen. These results suggest that the elicitation of stress response in TCNP treated chickpea during FOC interaction play a vital role in suppressing the wilt disease in chickpea.

Changes in the abscisic acid, phenylpropanoids and ascorbic acid metabolism during strawberry fruit growth and ripening

The functional compounds and sensory attributes of strawberries are acquired during ripening; however, the molecular mechanisms regulating this process have not yet been fully elucidated. Therefore, in this study, we aimed to investigate the accumulation of abscisic acid (ABA), phenylpropanoids, and l-ascorbic acid (AsA) as well as their relative gene expression levels during this process. The accumulation of ABA during the fruit growth and ripening stages depends on the upregulation of FaNCED1 and FaNCED2 gene expression, and the downregulation of FaCYP707 expression. Moreover, in the initial stages, the ABA glycosylation pathway is activated as a provision for the ABA levels required for future events. As the ABA levels increase, FaPAL, FaC4H1, and FaC4H4 genes expression are upregulated, aiding in the synthesis of flavonoid precursors, which, in addition to the higher FaUFGT expression, directly reflects an improvement in anthocyanin. AsA content increases during fruit development and ripening and is dependent on the synthesis pathway, due to the upregulation of FaGLDH expression, and on the oxidation and recycling pathways via the regulation of expression levels of FaAPX and FaMR. These results suggest that the activation of FaNCED1 and the inhibition of FaCYP707A1 may contribute to the increase in ABA content, thereby stimulating anthocyanin and AsA synthesis and accumulation.

Different Fruit-Specific Promoters Drive AtMYB12 Expression to Improve Phenylpropanoid Accumulation in Tomato.

Tomato is an economically crucial vegetable/fruit crop globally. Tomato is rich in nutrition and plays an essential role in a healthy human diet. Phenylpropanoid, a critical compound in tomatoes, reduces common degenerative and chronic diseases risk caused by oxidative stress. As an MYB transcription factor, ATMYB12 can increase phenylpropanoid content by activating phenylpropanoid synthesis related genes, such as PAL, C4H, 4CL, CHS. However, the heterologous expression of AtMYB12 in tomatoes can be altered through transgenic technologies, such as unstable expression vectors and promoters with different efficiency. In the current study, the efficiency of other fruit-specific promoters, namely E8S, 2A12, E4, and PG, were compared and screened, and we determined that the expression efficiency of AtMYB12 was driven by the E8S promoter was the highest. As a result, the expression of phenylpropanoid synthesis related genes was regulated by AtMYB12, and the phenylpropanoid accumulation in transgenic tomato fruits increased 16 times. Additionally, the total antioxidant capacity of fruits was measured through Trolox equivalent antioxidant capacity (TEAC) assay, which was increased by 2.4 times in E8S transgenic lines. TEAC was positively correlated with phenylpropanoid content. Since phenylpropanoid plays a crucial role in the human diet, expressing AtMYB12 with stable and effective fruit-specific promoter E8S could improve tomato’s phenylpropanoid and nutrition content and quality. Our results can provide genetic resources for the subsequent improvement of tomato varieties and quality, which is significant for human health.

Effect of cytokinins on growth and phenylpropanoid accumulation in Tartary buckwheat sprouts (Fagopyrum esculentum Moench)

This study analyzed the effect of plant hormones, zeatin, 6-benzyl amino purine (BAP), kinetin, and thidiazuron (TDZ) on the growth of Tartary buckwheat sprouts and analyzed the fresh weight, shoot and root length, and production of phenolic compounds. All the hormone-treated plants at the lowest concentration (0.1 mg/L) showed the highest levels of growth parameters (fresh weight, shoot, and root length) when compared to the control. Among the various hormones treatment, the plant treated with 1 mg/L of BAP, kinetin, and zeatin showed the highest total phenolic level, whereas the TDZ showed the highest accumulation of total phenolic at the lowest concentration (0.1 mg/L). A total of 6 compounds were identified (4-hydroxybenzoic acid, caffeic acid, chlorogenic acid, p-coumaric acid, rutin, and trans-cinnamic acid) were quantified by high liquid performance chromatography (HPLC) after treatment of plant with different concentrations of hormones. Among these individual phenolic compounds, at the higher hormonal concentration (1 mg/L) the rutin showed the highest accumulation in BAP, zeatin, and kinetin treated sprout, whereas in the TDZ treated sprout the rutin content was highest at the lowest concentration (0.1 mg/L). From these results, it is suggested that BAP, zeatin, and kinetin at the lowest concentrations might positively enhance the growth of buckwheat sprouts, whereas at the highest hormonal treatment the accumulation of the phenolic compounds was higher. However, in TDZ treatment the growth and phenolic compound accumulation were highest at the lowest concentration. From these results, it is showed that suitable concentrations might enhance the growth and phenolic compound accumulation in Tatary buckwheat sprout.

Trichoderma and Phosphite Elicited Distinctive Secondary Metabolite Signatures in Zucchini Squash Plants

Plant biostimulants are “green” solutions to improve crop production. Trichoderma spp. and phosphites, ordinarily used as biocontrol agents, can trigger phytostimulation, also promoting endogenous mechanisms involved in plant growth and development. The present study aimed at assessing the efficacy of a phosphite-based formulation (Phosphit-One) and Trichoderma harzianum-T22 on the morpho-physiological response and modulation of the metabolomics profile in zucchini squash plants (Cucurbita pepo L.) cultivated in controlled growth conditions (Fitotron®). The highest values of fresh biomass production (390.9 g plant−1) and root dry weight (5.6 g plant−1) were obtained for Trichoderma-treated plants. This last treatment resulted in an improved physiological performance (SPAD index, CO2 assimilation rate, and Fv/Fm ratio) measured 30 days after transplanting. Both Trichoderma and phosphite treatments induced a broad metabolic reprogramming in leaves, evident also for the phosphite treatment that did not result in a growth promotion. The microbial and the non-microbial treatments showed distinctive signatures in secondary metabolism yet, common responses could be also highlighted. For instance, both Trichoderma and phosphite triggered ROS-mediated signaling processes, together with the accumulation of phenylpropanoids, glucosinolates, and phytoalexins. Furthermore, a significant alteration of phytohormones was observed, with terpenoid gibberellins and brassinosteroids showing the largest differences. The metabolomic signatures induced by Trichoderma and phosphite in zucchini squash provided molecular insights into the processes underlying elicitation of plant defense due to biostimulation. Interestingly, the modulation of plant secondary metabolism by both treatments did not impair plant growth.