Accumulation Of Phenolic Compounds Research Articles

Synergistic role of melatonin and hydrogen sulfide in modulating secondary metabolites and metal uptake/sequestration in arsenic-stressed tomato plants

The multifunctional roles of melatonin (ML) and hydrogen sulfide (H2S) as plant gasotransmitters are well understood. However, their interaction in defensive responses is still unclear. Here, we assessed how the ML-H2S interaction impacts tomato plants exposed to arsenic (As, 10 mg/L) toxicity. The results showed that ML and ML+H2S treatments alleviated As toxicity by inducing the transcription of ANS, PAL, DFR, CHS, F3H, and CHI and an enhanced accumulation of phenolic and anthocyanin compounds. ML and ML+H2S led to a drop in the transcription of PT2 and Lsi1, resulting in reduced As uptake and subsequent movement to the leaves. ML and ML+H2S treatments resulted in high GSH1, PCS, and ABC1 transcription. This led to elevated levels of glutathione and phytochelatins, facilitating As sequestration in the roots and protecting root and leaf cells against As. ML and ML+H2S treatments enhanced tomato growth under As treatments by optimizing chlorophyll metabolism, increasing internal H2S, and amplifying the antioxidant machinery function. In contrast to the sole use of ML treatment, ML+H2S exhibited more pronounced positive impacts on As-stressed tomatoes, indicating synergistic/interactive effects between these two substances. On the other hand, the use of hypotaurine, an H2S scavenger, demonstrated the inhibition of the beneficial impact of ML and ML+H2S treatments in stimulating defensive responses, which highlights the substantial involvement of H2S in the signaling pathway activated by ML during As stress. Hence, we can conclude that ML requires the presence of endogenous H2S to mitigate the adverse effects of As on tomato seedlings.

Investigating the simultaneous effect of chitosan and arbuscular mycorrhizal fungi on growth, phenolic compounds, PAL enzyme activity and lipid peroxidation in Salvia nemorosa L.

Considering the importance of Salvia nemorosa L. in the pharmaceutical and food industries, and also beneficial approaches of arbuscular mycorrhizal fungi (AMF) symbiosis and the use of bioelicitors such as chitosan to improve secondary metabolites, the aim of this study was to evaluate the performance of chitosan on the symbiosis of AMF and the effect of both on the biochemical and phytochemical performance of this plant and finally introduced the best treatment. Two factors were considered for the factorial experiment: AMF with four levels (non-inoculated plants, Funneliformis mosseae, Rhizophagus intraradices and the combination of both), and chitosan with six levels (0, 50, 100, 200, 400 mg L-1 and 1% acetic acid). Four months after treatments, the aerial part and root length, the levels of lipid peroxidation, H2O2, phenylalanine ammonia lyase (PAL) activity, total phenol and flavonoid contents and the main secondary metabolites (rosmarinic acid and quercetin) in the leaves and roots were determined. The flowering stage was observed in R. intraradices treatments and the highest percentage of colonization (78.87%) was observed in the treatment of F. mosseae×400 mg L-1 chitosan. Furthermore, simultaneous application of chitosan and AMF were more effective than their separate application to induce phenolic compounds accumulation, PAL activity and reduce oxidative compounds. The cluster and principal component analysis based on the measured variables indicated that the treatments could be classified into three clusters. It seems that different treatments in different tissues have different effects. However, in an overview, it can be concluded that 400 mg L-1 chitosan and F. mosseae×R. intraradices showed better results in single and simultaneous applications. The results of this research can be considered in the optimization of this medicinal plant under normal conditions and experiments related to abiotic stresses in the future.

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.

ФИЗИОЛОГИЧЕСКИЕ ОСОБЕННОСТИ СОРТОВ ГРУШИ НА ТЕРРИТОРИИ КРАСНОДАРСКОГО КРАЯ

The search for new promising pear varieties with high adaptation and production potential is an important aim of modern breeding for the southern regions of the Russian Federation. In present study, the results of the physiological characteristics of four pear varieties during the summerautumn season 2022-2023 are presented. Pear trees were planted in the territory of the Prikubanskaya fruit growing in the Krasnodar Region. Three varieties Leven, Lyuberskaya, Flamenco of Russian breeding and the American variety Devo were used. The pear leaves were selected three times during the summer months and in September. The content of soluble sugars and total phenols, as well as the activity of antioxidant enzymes – superoxide dismutase and peroxidase – were determined in the plant material. It was established that an increase of the level of the primary and secondary metabolites accumulation and an increase of enzymatic activity by ~20-75 % occurred in the hotter and drier 2023. The content of soluble sugars significantly increased to ~12.0 mg/g fresh weight in the leaves of the varieties Devo and Leven. The accumulation of phenolic compounds increased in all pear varieties by more than 30 % with values exceeding 27,0 mg/g fresh weight. The level of superoxide dismutase activity in 2023 averaged 13.4 unit/mg protein, which is slightly higher than the values of 2022. Peroxidase activity increased 2-4 times with maximum values of more than 8,0 unit/mg protein per min. in the varieties Leven and Lyuberskaya. In conclusion, the data obtained indicate that the drier and hotter conditions of 2023 were not critical for the normal growth and development of the studied pears varieties, but only initiated the activation of the defense antioxidant system in plant cells. Key words: PEAR, PRIMARY AND SECONDARY METABOLITES, ANTIOXIDANT ENZYME ACTIVITY

Impact of Seed Inoculation with Trichoderma afroharzianum Strains on Plant Growth, Root Morphology, and Leaf Phenolic Content in Hemp (Cannabis sativa L.) at Early Growth Stages

Industrial hemp (Cannabis sativa L.) is receiving increasing attention for its multiple end-uses; therefore, an improvement in its production is needed to meet the increased demand. In the present study, the effect of seed inoculation with two Trichoderma afroharzianum strains, T-AA and T-22, on plant growth and root morphology of hemp plants at sixth-leaf (S6) and tenth-leaf (S10) stages was assessed for two consecutive years (2020 and 2021). In addition, the ability of the two strains to enhance the accumulation of phenolic compounds in hemp leaves was also evaluated. The results obtained revealed the ability of T-22 to improve the growth and root morphology of hemp plants both in 2020 and 2021, although with different impact, probably ascribable to the different weather conditions in the two years. In 2020, the positive effects of T-22 were detected at S10 stage with significant increases in the shoot and root length (38% and 17%, respectively) and dried biomass (35% and 30%, respectively) compared to untreated plants. The total root surface area and the number of tips, forks, and crossings also increased significantly (24–36%) at this stage. In 2021, significant increases in the shoot length and dried biomass (40% and 30%, respectively) were observed at S6 stage, whereas root length and dried biomass increased significantly at S6 (55% and 47%, respectively) and S10 stage (121% and 40%, respectively). Significant increases in the total surface area and volume, as well as in the number of tips, forks, and crossings were also observed at both S6 and S10 stage (50–63% and 105–187%, respectively). Interestingly, in both years and at both stages, the two strains induced significant increases in the leaf accumulation of phenolic compounds and the antioxidant activity, which were greater in T-22- compared to T-AA-treated plants (18–102% and 13–34%, respectively). The results are discussed in light of the potential practical applications of T-22 as a biostimulant of hemp plant growth under favorable and unfavorable environmental conditions, and of both strains as promising tools for the improvement of the leaves’ economic value as a source of health-promoting compounds.

Cadmium stress responses under white or blue light are influenced by putrescine pre-treatment in wheat

Blue light plays an important role in most plant functions: it influences plant morphology, photosynthesis, primary and secondary metabolism. Although certain studies have already revealed that blue light may have positive effects under certain stress conditions, its exact mechanism is largely unknown. The importance of polyamines in stress tolerance has been widely investigated; however, their interaction with the dependent processes is still poorly understood. In addition, the quality of light can also affect the polyamine metabolism, thus it can influence their roles and relationships with other protective compounds. According to these, the main question of the present work was that whether blue light induces different responses during Cd stress, especially which are related to polyamine metabolism, and whether it may be able to modify the protective effect of exogenous putrescine compared to white light conditions in wheat. It has been demonstrated that less pronounced Cd stress was detected under blue light than at white light conditions. Blue light had its own effect at metabolite and gene expression levels and the lower Cd uptake was accompanied by lower phytochelatin but higher conjugated polyamine accumulation at the same time. Putrescine pre-treatment had protective effect especially under white light conditions, and it highlighted certain differences observed under Cd stress between blue light and white light conditions, especially in phytochelatin synthesis, polyamine metabolism, and accumulation of phenolic compounds and plant hormones. Our data demonstrated that blue light regulated Cd tolerance in wheat and modified defence strategy when excess putrescine was present.

Effects of Biochar and Arbuscular Mycorrhizal Fungi on Soil Health in Chinese Kale (Brassica oleracea var. alboglabra L.) Cultivation

Biochar and arbuscular mycorrhizal fungi (AMF), a promising environmentally friendly soil enhancer and biostimulant, play a crucial role in sustainable agriculture by influencing soil properties and plant growth. This research investigates the chemical properties of three biochar types [bamboo (BB-char), corn cob (CC-char), and coffee grounds (CG-char)] derived from different biomass sources and their impact on soil quality and Chinese kale growth. The results reveal significant differences in chemical properties among different types of biochar. Particularly, CG-char showed the greatest pH value and phosphorus content, with an average of 10.05 and 0.44%, respectively. On the other hand, CC-char had the highest potassium content, with an average of 2.16%. Incorporating biochar into degraded soil enhances soil structure, promoting porosity and improved texture, as evidenced by scanning electron microscope images revealing distinct porous structures. Soil chemistry analyses in treatment T2–T14 after a 42-day cultivation demonstrate the impact of biochar on pH, electrical conductivity, organic matter, and organic carbon levels in comparison to the control treatment (T1). Furthermore, the research assesses the impact of biochar on Chinese kale growth and photosynthetic pigments. Biochar additions, especially 5% BB-char with AMF, positively influence plant growth, chlorophyll content, and photosynthetic pigment levels. Notably, lower biochar concentrations (5%) exhibit superior effects compared to higher concentrations (10%), emphasizing the importance of optimal biochar application rates. The study also delves into the total phenolic content in Chinese kale leaves, revealing that the synergistic effect of biochar and AMF enhances phenolic compound accumulation. The combination positively influences plant health, soil quality, and nutrient cycling mechanisms. Overall, the research indicates the multifaceted impact of biochar on soil and plant dynamics, emphasizing the need for tailored application strategies to optimize benefits in sustainable agriculture.

Postharvest Chemical Treatment of Physiologically Induced Stem End Blockage Improves Vase Life and Water Relation of Cut Flowers

Wound-induced xylem occlusion significantly affects the vase life of cut flowers, as oxidative stress and the polymerization of phenolic compounds lead to the deposition of phenolic compounds/secondary metabolites in the stem ends of cut flowers to heal open tissues of freshly cut stems and prevent microbial invasion. However, this deposition causes blockage of vessels, reduced water uptake, and shortened vase life. The physiological plugging of vessels is linked with various oxidative enzymes’ (PAL, PPOs, LACs, and COs) actions taken to increase the synthesis of different compounds, e.g., lignin, suberin, tyloses, gel, and latex, in wounded areas. The use of chemical preservatives/enzyme inhibitors is one of the safest and most efficient techniques employed to minimize vascular blockage and inhibit phenolic compounds deposition and exudation. This review mainly discusses the types of oxidative enzymes, their pathways and biochemistry along with production of secondary metabolites, their biosynthesis, and their modes of action involved in vascular blockage. It also summarizes the different types of preservatives used in postharvest treatments to improve relative water uptake, flower fresh weight, petal protein content, and hydraulic conductance and prolong the vase life of cut flowers during storage. It is hoped that this elaborate study will help researchers in designing new studies concerning occlusion caused by the accumulation of phenolic compounds in vessels.

Phenolic compounds weaken the impact of drought on soil enzyme activity in global wetlands.

Soil enzymes play a central role in carbon and nutrient cycling, and their activities can be affected by drought-induced oxygen exposure. However, a systematic global estimate of enzyme sensitivity to drought in wetlands is still lacking. Through a meta-analysis of 55 studies comprising 761 paired observations, this study found that phosphorus-related enzyme activity increased by 38% as result of drought in wetlands, while the majority of other soil enzyme activities remained stable. The expansion of vascular plants under long-term drought significantly promoted the accumulation of phenolic compounds. Using a 2-week incubation experiment with phenol supplementation, we found that phosphorus-related enzyme could tolerate higher biotoxicity of phenolic compounds than other enzymes. Moreover, a long-term (35 years) drainage experiment in a northern peatland in China confirmed that the increased phenolic concentration in surface layer resulting from a shift in vegetation composition inhibited the increase in enzyme activities caused by rising oxygen availability, except for phosphorus-related enzyme. Overall, these results demonstrate the complex and resilient nature of wetland ecosystems, with soil enzymes showing a high degree of adaptation to drought conditions. These new insights could help evaluate the impact of drought on future wetland ecosystem services and provide a theoretical foundation for the remediation of degraded wetlands.

Melatonin supplementation enhances browning suppression and improves transformation efficiency and regeneration of transgenic rough lemon plants (Citrus × jambhiri).

Enzymatic browning poses a significant challenge that limits in vitro propagation and genetic transformation of plant tissues. This research focuses on investigating how adding antioxidant substances can suppress browning, leading to improved efficiency in transforming plant tissues using Agrobacterium and subsequent plant regeneration from rough lemon (Citrus × jambhiri). When epicotyl segments of rough lemon were exposed to Agrobacterium, they displayed excessive browning and tissue decay. This was notably different from the 'Hamlin' explants, which did not exhibit the same issue. The regeneration process failed completely in rough lemon explants, and they accumulated high levels of total phenolic compounds (TPC) and polyphenol oxidase (PPO), which contribute to browning. To overcome these challenges, several antioxidant and osmoprotectant compounds, including lipoic acid, melatonin, glycine betaine, and proline were added to the tissue culture medium to reduce the oxidation of phenolic compounds and mitigate browning. Treating epicotyl segments with 100 or 200 μM melatonin led to a significant reduction in browning and phenolic compound accumulation. This resulted in enhanced shoot regeneration, increased transformation efficiency, and reduced tissue decay. Importantly, melatonin supplementation effectively lowered the levels of TPC and PPO in the cultured explants. Molecular and physiological analyses also confirmed the successful overexpression of the CcNHX1 transcription factor, which plays a key role in imparting tolerance to salinity stress. This study emphasizes the noteworthy impact of supplementing antioxidants in achieving successful genetic transformation and plant regeneration in rough lemon. These findings provide valuable insights for developing strategies to address enzymatic browning and enhance the effectiveness of plant tissue culture and genetic engineering methods with potential applications across diverse plant species.

Expression Analysis of Phenylpropanoid Pathway Genes and Phenylpropanoid Accumulation in Different Organs of Chelidonium majus L.

Objective This study set out to examine the phenylpropanoid pathway gene expression and phenolic compound accumulation in different organs of Chelidonium majus (C. majus). Methods Total RNA was extracted and expression of phenylpropanoid biosynthesis genes was assessed using quantitative real-time polymerase chain reaction in different organs of C. majus. In addition, the phenylpropanoid compounds were analyzed from different organs of C. majus by using high-performance liquid chromatography. Results The results demonstrate the variance in the expression levels of phenylpropanoid pathway genes in the flowers, leaves, stems, and roots of C. majus. CmPAL and CmC4H were expressed at their greatest levels in the stem, while CmCHS and CmCHI were strongly expressed in the leaf, and CmF3H, CmFLS, Cm4CL, and CmDFR were more abundant in the flower. The total phenolic contents in the different organs also varied significantly. The highest value was recorded in the flowers (2152.89  ±  78.71 μg/g dry wt.), which was 54.26 times higher than the lowest values obtained from roots (39.68  ±  0.05 μg/g dry wt.). Except for roots, rutin showed the highest level in all other organs. According to a heat map, the majority of the phenolic compounds were highest in the flower. By using variable importance in projection analysis, the most significant metabolite was found to be chlorogenic acid, which had a positive association with all phenolic chemicals, but it showed a negative correlation with trans-cinnamic acid. Except for trans-cinnamic acid, all other phenolic compounds likewise showed positive correlation with other phenolic compounds. Conclusions This work offers pertinent data on the expression analysis of genes involved in the phenylpropanoid biosynthetic pathway and the presence of phenolic compounds in C. majus. These findings will be helpful for the researcher to understand the relationship between the expression level of phenylpropanoid pathway genes and phenylpropanoid compound accumulation in C. majus.

Enhancing Antioxidant and Antimicrobial Activities in Bee-Collected Pollen through Solid-State Fermentation: A Comparative Analysis of Bioactive Compounds.

The present study investigates the impact of solid-state fermentation on bee-collected pollen using a consortium of Lactobacillus plantarum, Apilactobacillus kunkeei, and Lactobacillus acidophilus. Another aim is to compare the nutritional and bioactive properties of natural versus fermented pollen, focusing on macronutrient composition, pH, acidity, lactic acid content, and profiles of polyphenolics and flavonoids. Our results indicated significant enhancements in the contents of amino acids, suggesting improved protein content, alongside increases in polyphenolic and flavonoid contents post-fermentation. According to the heat mapping and cluster analysis, increased antioxidant and antimicrobial activities against Gram-positive and Gram-negative bacteria, particularly E. coli, were observed in the fermented bee-collected pollen samples, which may have been due to the accumulation of phenolic compounds (e.g., ellagic acid, kaempferol, quercetin, and quercetin-3-O-rutinoside). Furthermore, significant positive correlations of the fermented bee-collected pollen samples with non-essential amino acids were recorded compared with the unfermented bee-collected pollen samples, which may have been due to the fermentation process and the conversion of proteins into free amino acids via proteolysis. Future research could explore the underlying mechanisms, the scalability of fermentation, its application in functional foods, and the health benefits of fermented bee-collected pollen in human diets.

Effect of two biocontrols on the accumulation of phenolic compounds and leaf pigments in sorghum [<i>Sorghum bicolor</i> (L.) Moench] leaves in northern Côte d'Ivoire

The aim of this study was to find an alternative to chemical control by improving sorghum's natural defense system. The effect of two  biocontrols, Vacciplant and Calliet, on phenolic compound and leaf pigment levels was evaluated. Vacciplant was prepared at  concentrations of 0.675; 0.9; 1.125; 1.35 and 1.575 mg/mL, while Calliet was prepared at concentrations of 4 ; 8 ; 12 ; 16 and 20 mg/mL.  After preparation, the biocontrol solutions were sprayed onto sorghum leaves 60 days old. Incubation times of 24, 48, 72 and 96 hours  were observed after spraying. The sorghum leaves were then harvested and freeze-dried for quantification of total phenols and leaf  pigments. Results showed that Vacciplant at a concentration of 1.125 mg/mL after 72 hours of incubation allowed to have the highest  contents of total phenols (76.63 mg/g MF), while Calliet at concentration of 4.00 mg/mL after 24 hours of incubation allowed to have the  highest contents of total phenols (67.28 mg/g MF). With regard to photosynthetic activity, the results also showed an increase in leaf  pigment content following the application of biocontrols. The use of biocontrols could therefore be an interesting alternative to chemical  control in sorghum.

Development and characterization of a new sunflower source of resistance to race G of Orobanche cumana Wallr. derived from Helianthus anomalus

Key messageA new OrAnom1 gene introgressed in cultivated sunflower from wild Helianthus anomalusconfers late post-attachment resistance toOrobanche cumana race G and maps to a target interval in Chromosome 4 where two receptor-like kinases (RLKs) have been identified in theH. anomalusgenome as putative candidates.Sunflower broomrape is a parasitic weed that infects sunflower (Helianthus annuus L.) roots causing severe yield losses. Breeding for resistance is the most effective and sustainable control method. In this study, we report the identification, introgression, and genetic and physiological characterization of a new sunflower source of resistance to race G of broomrape developed from the wild annual sunflower H. anomalus (accession PI 468642). Crosses between PI 468642 and the susceptible line P21 were carried out, and the genetic study was conducted in BC1F1, BC1F2, and its derived BC1F3 populations. A BC1F5 germplasm named ANOM1 was developed through selection for race G resistance and resemblance to cultivated sunflower. The resistant trait showed monogenic and dominant inheritance. The gene, named OrAnom1, was mapped to Chromosome 4 within a 1.2 cM interval and co-segregated with 7 SNP markers. This interval corresponds to a 1.32 Mb region in the sunflower reference genome, housing a cluster of receptor-like kinase and receptor-like protein (RLK-RLP) genes. Notably, the analysis of the H. anomalus genome revealed the absence of RLPs in the OrAnom1 target region but featured two RLKs as possible OrAnom1 candidates. Rhizotron and histological studies showed that OrAnom1 determines a late post-attachment resistance mechanism. Broomrape can establish a vascular connection with the host, but parasite growth is stopped before tubercle development, showing phenolic compounds accumulation and tubercle necrosis. ANOM1 will contribute to broadening the genetic basis of broomrape resistance in the cultivated sunflower pool and to a better understanding of the molecular basis of the sunflower-broomrape interaction.

Effect of Fertilization on Phenolics of Rapeseeds and Their Antioxidant Potential.

Three varieties of rapeseed (Castilla, California, and Nelson F1) were cultivated using medium-intensive (control), intensive, and economical (spare) technologies with different nitrogen and sulfur fertilization techniques. The antioxidant potential of rapeseeds was investigated using ABTS, FRAP, and DPPH assays. The content of total phenolic compounds was determined using the Folin-Ciocalteu phenol reagent. The profile of phenolic compounds was determined using high-performance liquid chromatography (HPLC). Diversifying fertilization in various ways influenced the content of phenolic compounds in extracts of rapeseed. In extracts from the Nelson F1 rapeseeds, intensive cultivation resulted in a lower content of phenolic compounds compared to the control group. Economic fertilization reduced the content of phenolic compounds in seeds from the California variety. HPLC chromatograms of the extracts were characterized by the presence of five (California and Castilla) and six (Nelson F1) main phenolic compounds. Two compounds were identified as sinapine and sinapic acid; others were classified as derivatives of sinapic acid. The effect of fertilization on the antioxidant activity of the seeds and their extracts varied depending on the plant variety and antioxidant assay. For the Castilla and California varieties, no differences were found in the results of the ABTS assay. The antiradical activity against ABTS•+ of extracts from the Nelson F1 intensive and spare cultivated seeds was higher than that of extracts from control seeds. The FRAP values of extracts/seeds from the Castilla variety cultivated using different methods did not differ significantly. The results of the DPPH assay were not affected by fertilization in the case of extracts from the California and Castilla varieties. However, the extracts from spare cultivated seeds of Nelson F1 exhibited stronger antiradical activity against DPPH•. These findings highlight the complex relationship between fertilization practices, phenolic compound accumulation, and antioxidant activity in rapeseed. Integrating varietal traits and cultivation practices is crucial for optimizing the nutritional benefits of rapeseed.

Transcriptomic Analyses Reveal Insights into the Shared Regulatory Network of Phenolic Compounds and Steviol Glycosides in Stevia rebaudiana.

Stevia rebaudiana (Bertoni) is a highly valuable crop for the steviol glycoside content in its leaves, which are no-calorie sweeteners hundreds of times more potent than sucrose. The presence of health-promoting phenolic compounds, particularly flavonoids, in the leaf of S. rebaudiana adds further nutritional value to this crop. Although all these secondary metabolites are highly desirable in S. rebaudiana leaves, the genes regulating the biosynthesis of phenolic compounds and the shared gene network between the regulation of biosynthesis of steviol glycosides and phenolic compounds still need to be investigated in this species. To identify putative candidate genes involved in the synergistic regulation of steviol glycosides and phenolic compounds, four genotypes with different contents of these compounds were selected for a pairwise comparison RNA-seq analysis, yielding 1136 differentially expressed genes. Genes that highly correlate with both steviol glycosides and phenolic compound accumulation in the four genotypes of S. rebaudiana were identified using the weighted gene co-expression network analysis. The presence of UDP-glycosyltransferases 76G1, 76H1, 85C1, and 91A1, and several genes associated with the phenylpropanoid pathway, including peroxidase, caffeoyl-CoA O-methyltransferase, and malonyl-coenzyme A:anthocyanin 3-O-glucoside-6″-O-malonyltransferase, along with 21 transcription factors like SCL3, WRK11, and MYB111, implied an extensive and synergistic regulatory network involved in enhancing the production of such compounds in S. rebaudiana leaves. In conclusion, this work identified a variety of putative candidate genes involved in the biosynthesis and regulation of particular steviol glycosides and phenolic compounds that will be useful in gene editing strategies for increasing and steering the production of such compounds in S. rebaudiana as well as in other species.

Integrative metabolome and transcriptome profiling provide insights into elucidation of the synthetic mechanisms of phenolic compounds in Yunnan hulled wheat (Triticum aestivum ssp. yunnanense King).

Yunnan hulled wheat grains (YHWs) have abundant phenolic compounds (PCs). However, a systematic elucidation of the phenolic characteristics and molecular basis in YHWs is currently lacking. The aim of the study, for the first time, was to conduct metabolomic and transcriptomic analyses of YHWs at different developmental stages. A total of five phenolic metabolite classes (phenolic acids, flavonoids, quinones, lignans and coumarins, and tannins) and 361 PCs were identified, with flavonoids and phenolic acids being the most abundant components. The relative abundance of the identified PCs showed a dynamic decreasing pattern with grain development, and the most significant differences in accumulation were between the enlargement and mature stage, which is consistent with the gene regulation patterns of the corresponding phenolic biosynthesis pathway. Through co-expression and co-network analysis, PAL, HCT, CCR, F3H, CHS, CHI and bZIP were identified and predicted as candidate key enzymes and transcription factors. The results broaden our understanding of PC accumulation in wheat whole grains, especially the differential transfer between immature and mature grains. The identified PCs and potential regulatory factors provide important information for future in-depth research on the biosynthesis of PCs and the improvement of wheat nutritional quality. © 2024 Society of Chemical Industry.

The Biosynthesis, Accumulation of Phenolic Compounds and Antioxidant Response in Lactuca sativa L. Plants Inoculated with a Biofertilizer Based on Soil Yeast and Iron Nanoparticles

Lettuce is a vegetable that contributes vitamins, minerals, fibre, phenolic compounds and antioxidants to the human diet. In the search for improving production conditions and crop health, the use of microorganisms with plant growth-promoting capabilities, such as soil yeasts (PGPY), in conjunction with nanotechnology could offer sustainable development of agroecosystems. This study evaluated the synthesis of health-promoting bioactive compounds in lettuce under the application of soil yeast and an iron nanoparticle (NP-Fe2O3) encapsulated in alginate beads. Two yeast strains, Candida guillermondii and Rhodotorula mucilaginosa, and a consortium of both yeasts were used in the presence and absence of Fe2O3-NPs. Phenolic compounds were identified and quantified via HPLC-ESI-Q-ToF and antioxidant activity. Ten phenolic compounds were identified, highlighting the chicoric acid isomer and two quercetin glycosides with high concentrations of up to 100 µg g−1 in treatments with C. guillermondii. Treatments with R. mucilaginosa and NPs-Fe2O3 presented an increase in antioxidant activity, mainly in TEAC, CUPRAC and DPPH activities in leaves, with significant differences between treatments. Therefore, the use of encapsulated soil yeasts is a viable alternative for application in vegetables to improve the biosynthesis and accumulation of phenolic compounds in lettuce and other crops.

Microalgae Haemococcus pluvialis, Cultured in OHM Medium under Stressful Conditions: Phenolic Content and Antioxidant Capacity

Haematococcus pluvialis, a unicellular green microalgae, is able to accumulate the large amounts of astaxathin under stress conditions. Nutritional factors such as nitrate or phosphate and light intensity play an important role in the growth, accumulation of phenolic compounds and antioxidant capacity microalgae H. pluvialis. In this study, H. pluvialis was cultured under three conditions of stress, nutrient depletion, denitrification of nitrate and addition of NPK fertilizer, and natural light in OHM medium to investigate the phenolic content and antioxidant capacity of the biomass of H. pluvialis microalgae. The results showed that, under denitrification of nitrate and addition of NPK fertilizer, the phenolic content reached a high value (8.054 µg gallic acid/g) and there was no significant difference with the two conditions of nutrient depletion (4.115 µg gallic acid/g) and natural light (4.707 µg gallic acid/g) (p<0.05). However, no differences were found between the antioxidant capacity under denitrification of nitrate and addition of NPK fertilizer (51.390%) and natural light (52.301%) (p=0.552) that were higher than nutrient depletion (45.257%) (p<0.05). Thus, under the stress conditions of nitrate depletion and high light intensity, H. pluvialis has the ability to synthesize and accumulate high amounts of bioactive compounds and microalgae biomass can be applied in dietary supplement and cosmeticeuticals.

A Long-Term Study on Chemical Compounds and Their Location in Sweet Basil Leaves from Organic and Conventional Producers

Bioactive compound profiles in organic and conventional sweet basil were analyzed by HPLC, and the enzymatic status and antioxidant status of plants cultivated with the two systems were also examined. Fluorescence microscopy was used for the determination of compounds’ locations in the basil leaves. The experiment was conducted from 2019 to 2021. Organic and conventional basil samples were obtained directly from Polish herb producers. The results showed that the chemical profiles of organic and conventional basil leaves are different. Not only the cultivation method but also the experimental year had a significant impact on the antioxidant content in basil leaves. Organic basil contained significantly more dry matter (11.97 g 100 g−1 FW) compared to conventional one (10.54 g 100 g−1 FW) and a higher tendency for total phenolic compounds (5.24 mg g −1 DW) accumulation. The higher bioactive compound content reflects the antioxidant activity (61.0%, 54.33%, and 46%) in organic basil compared to conventional (46.87%, 38.055, and 39.24%) with respect to the analysis method (ABTS, DPPH, and FRAP). Catalase activity (39 µmol H2O2 min−1 mg−1) in organic basil was higher compared to conventional (23.19 µmol H2O2 min−1 mg−1) ones. The obtained results are very unique and could be used by herb producers as a key for high-quality basil production. The higher concentration of bioactive compounds in organic basil gives a better nutraceutical status to this popular herb.