Levels Of Primary Metabolites Research Articles

Changes in primary metabolism and associated gene expression during host-pathogen interaction in clubroot resistance of Brassica napus.

The role of primary metabolism during Brassica napus-Plasmodiophora brassicae interaction leading to clubroot resistance has not yet been investigated thoroughly. In this study, we investigated some of the primary metabolites and their derivatives as well as expression of the genes involved in their biosynthesis to decipher this host-pathogen interaction. For this, two sets (clubroot resistant and susceptible) of canola lines were inoculated with P. brassicae pathotype 3A to investigate the endogenous levels of primary metabolites at 7-, 14-, and 21-days after inoculation (DAI). The associated pathways were curated, and expression of the selected genes was analyzed using qRT-PCR. Our results suggested the possible involvement of polyamines (spermidine and spermine) in clubroot susceptibility. Some of the amino acids were highly abundant at 7- or 14-DAI in both resistant and susceptible lines; however, glutamine and the amino acid derivative phenylethylamine showed higher endogenous levels in the resistant lines at later stages of infection. Organic acids such as malic, fumaric, succinic, lactic and citric acids were abundant in the susceptible lines. Conversely, the abundance of salicylic acid (SA) and the expression of benzoate/salicylate carboxyl methyltransferase (BSMT) were higher in the resistant lines at the secondary stage of infection. A reduced disease severity index and gall size were observed when exogenous SA (1.0 mM) was applied to susceptible B. napus; this further supported the role of SA in clubroot resistance. In addition, a higher accumulation of fatty acids and significant upregulation of the pathway genes, glycerol-3-phosphate dehydrogenase (GPD) and amino alcohol phosphotransferase (AAPT) were observed in the resistant lines at 14- and 21-DAI. In contrast, some of the fatty acid derivatives such as phosphatidylcholines represented a lower level in the resistant lines. In conclusion, our findings provided additional insights into the possible involvement of primary metabolites and their derivatives in clubroot resistance.

Influence of Spotted Lanternfly (Lycorma delicatula) on Multiple Maple (Acer spp.) Species Canopy Foliar Spectral and Chemical Profiles

Invasive species have historically disrupted environments by outcompeting, displacing, and extirpating native species, resulting in significant environmental and economic damage. Developing approaches to detect the presence of invasive species, favorable habitats for their establishment, and predicting their potential spread are underutilized management strategies to effectively protect the environment and the economy. Spotted lanternfly (SLF, Lycorma delicatula) is a phloem-feeding planthopper native to China that poses a severe threat to horticultural and forest products in the United States. Tools are being developed to contain the spread and damage caused by SLF; however, methods to rapidly detect novel infestations or low-density populations are lacking. Vegetation spectroscopy is an approach that can represent vegetation health through changes in the reflectance and absorption of radiation based on plant physiochemical status. Here, we hypothesize that SLF infestations change the spectral and chemical characteristics of tree canopies. To test this hypothesis, we used a full range spectroradiometer to sample canopy foliage of silver maple (Acer saccharinum) and red maple (Acer rubrum) trees in a common garden in Berks County, Pennsylvania that were exposed to varying levels of SLF infestation. Foliar spectral profiles separated between SLF infestation levels, and the magnitude of separation was greater for the zero-SLF control compared with higher infestation levels. We found the red-edge and portions of the NIR and SWIR regions were most strongly related to SLF infestation densities and that corresponding changes in vegetation indexes related to levels of chlorophyll were influenced by SLF infestations, although we found no change in foliar levels of chlorophyll. We found no influence of SLF densities on levels of primary metabolites (i.e., pigments, nonstructural carbohydrates, carbon, and nitrogen), but did find an increase in the phenolic compound ferulic acid in response to increasing SLF infestations; this response was only in red maple, suggesting a possible species-specific response related to SLF feeding. By identifying changes in spectral and chemical properties of canopy leaves in response to SLF infestation, we can link them together to potentially better understand how trees respond to SLF feeding pressure and more rapidly identify SLF infestations.

Deciphering the benefits and intensity levels of primary metabolites from Allium macrostemon Bunge and Allium chinense G. Don

BackgroundAllii Macrostemonis Bulbus is also named Xiebai in China. It is an edible vegetable, and also a famous herb for treating coronary heart disease. Allium chinense G. Don (ACGD) and Allium macrostemon Bunge (AMB) are it botanical sources. The aim of this study was to explore the cardioprotective effects, and decipher the visual spatial distribution and absolute content of primary metabolites derived from these two herbs.MethodsH9c2 cells were used to perform the hypoxia-reoxygenation (H/R)-induced myocardial injury model. Their protective effects were evaluated by apoptosis levels. Furthermore, matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry imaging approach (MALDI-TOF MSI) was carried out to present the spatial location of primary metabolites including fatty acids, amino acids, carotenoids, and vitamins in these two Allium herbs. Multiple analytical methods were applied to perform quantitative analysis of these primary metabolites in AMB and ACGD bulbs by liquid chromatography tandem mass spectrometry (LC–MS).ResultsFirst, AMB and ACGD extracts both could increase the cell viability in H9c2 cells, and attenuate H/R-induced injury. They markedly decreased apoptosis, accompanied by activating the BCL-2/BAX pathway. Further, MALDI-TOF MSI-based relative quantification results showed several amino acids, fatty acids, carotenoids, and vitamins were largely rich in the tunics and outside scales of fresh bulbs, while some primary metabolites were abundant in their developing flower buds. Absolute quantification results displayed total contents of amino acids in ACGD bulbs were higher than those in AMB, while total contents of fatty acids and vitamins provides opposite trends in these two Allium herbs. The total contents of carotenoids and trace elements showed no significant differences between AMB and ACGD samples.ConclusionsThis study would be helpful to understand the myocardial injury protection effects of these two Allium herbs, and the spatial accumulation and quantitative content levels of their main nutrients.Graphical

Metabolomics analysis of bahia grass (Paspalum notatum) inoculated with arbuscular mycorrhizal fungi exposed to soil Cd stress

Heavy metals can adversely affect the growth and metabolic processes of plant. Arbuscular mycorrhizal (AM) fungi, which colonize the roots of most plants, may change the uptake and resistance to heavy metals by altering plant metabolism. But few published papers focused on how AM fungi enhanced plant tolerance to heavy metals at the metabolomics level. Therefore, our study incorporated LC-MS technology to explore the molecular mechanism by which AM fungi improved cadmium (Cd) tolerance of Bahia grass (Paspalum notatum) at the metabolomic scale. The results showed that AM fungi increased growth of Bahia grass, and enhanced its uptake and tolerance of Cd. Infection with AM fungi significantly raised the levels of both primary metabolites (amino acid, carbohydrate, organic acid, etc.) and secondary metabolites (such as terpenoids, phenolic compounds, and alkaloids), which in turn improved the photosynthesis efficiency, osmoregulation, and antioxidation defense of the plant, thereby enhancing the Cd tolerance of Bahia grass. Furthermore, under high concentration of Cd, both TCA cycle and lipid metabolism were generally suppressed, and AM fungi inoculation alleviated the effects and normalized the TCA cycle and lipid metabolism. In all, the metabolic alterations identified here provided insights into the mechanisms by which AM fungi enhanced plant tolerance to heavy metals.

Arbuscular mycorrhizal symbiosis allows to overcome phosphorus deficiency in soilless culture of Lactuca sativa: A phenotypic and transcriptomic analysis

Lettuce (Lactuca sativa L.) is an annual autogamous diploid plant belonging to Asteraceae and is among the top ten most profitable crops worldwide due to its nutritional value. Nevertheless, lettuce is an intensive crop with high input demand, especially fertilisers, both in soil-bound and soilless culture, with negative impact on the environment and production costs. In this context, arbuscular mycorrhizal symbioses could help to reduce the impact of fertilisers, improving plant nutrition, particularly regarding phosphorus, and contributing to growing healthier plants for human consumption. In our work, we compared lettuce plants (cv. Salinas) grown in soilless culture with optimal phosphorus concentration in the nutrient solution, with sub-optimal phosphorus nutrition and with plants grown with sub-optimal phosphorus concentration and inoculated with the fungus Funneliformis mosseae before transplanting.Higher levels of primary and secondary metabolites along with increased biomass were observed for mycorrhizal plants compared to lettuces grown with optimal and sub-optimal concentrations of phosphate. Gene expression profile was analysed in both roots and leaves, and transcriptomic values were associated with growth and biochemical parameters. Three-thousand and fifty-seven genes were differentially regulated by mycorrhizal symbiosis and 2,606 genes by optimal phosphate nutrition.Different genes related to photosynthesis, solute transport, metabolism of phytohormones, redox homeostasis, and transcriptional regulation resulted differentially regulated between culture conditions. Mycorrhizal plants also boosted the activation of genes involved in phenylpropanoids and carotenoids metabolism. In conclusion, growth, biochemical, and transcriptomic data show that symbiotic plants benefit both plant growth and leaf content of health promoting phytochemicals through genetic pathways that largely differed those activated in plants grown with optimal phosphorus supply.

Impacts of Arbuscular Mycorrhizal Fungi on Metabolites of an Invasive Weed Wedelia trilobata.

The invasive plant Wedelia trilobata benefits in various aspects, such as nutrient absorption and environmental adaptability, by establishing a close symbiotic relationship with arbuscular mycorrhizal fungi (AMF). However, our understanding of whether AMF can benefit W. trilobata by influencing its metabolic profile remains limited. In this study, Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was conducted to analyze the metabolites of W. trilobata under AMF inoculation. Metabolomic analysis identified 119 differentially expressed metabolites (DEMs) between the groups inoculated with AMF and those not inoculated with AMF. Compared to plants with no AMF inoculation, plants inoculated with AMF showed upregulation in the relative expression of 69 metabolites and downregulation in the relative expression of 50 metabolites. AMF significantly increased levels of various primary and secondary metabolites in plants, including amino acids, organic acids, plant hormones, flavonoids, and others, with amino acids being the most abundant among the identified substances. The identified DEMs mapped 53 metabolic pathways, with 7 pathways strongly influenced by AMF, particularly the phenylalanine metabolism pathway. Moreover, we also observed a high colonization level of AMF in the roots of W. trilobata, significantly promoting the shoot growth of this plant. These changes in metabolites and metabolic pathways significantly affect multiple physiological and biochemical processes in plants, such as free radical scavenging, osmotic regulation, cell structure stability, and material synthesis. In summary, AMF reprogrammed the metabolic pathways of W. trilobata, leading to changes in both primary and secondary metabolomes, thereby benefiting the growth of W. trilobata and enhancing its ability to respond to various biotic and abiotic stressors. These findings elucidate the molecular regulatory role of AMF in the invasive plant W. trilobata and provide new insights into the study of its competitive and stress resistance mechanisms.

Response of Metabolites in Cymbopogon distans Leaves to Water Addition in Karst Areas during Different Seasons

Climate change could influence the plant response to drought stress in karst environments. However, fewer related studies have been reported. This study examined the impact of artificial water addition on the accumulation of metabolites of Cymbopogon distans with a non-targeted metabolomics approach during both the dry and wet seasons. Three water treatment gradients (CK, T1, and T2, indicating 0%, +20%, and +40% relative to the average monthly precipitation, respectively) were chosen. The findings of our study indicate that the levels of primary metabolites were higher in the leaves of C. distans during the dry season compared to the rainy season. In addition, the presence of water did not have a substantial impact on the composition and functionality of metabolites between the wet and drought seasons. The contents of some lipids were greater during the dry season, while others were greater during the wet season. During the dry season, the contents of FA, DG, MGDG, SQDG, TG, and PR decreased with water addition. Our findings demonstrated that artificial water addition might have a greater impact on metabolite accumulation during the dry season in drought-tolerant species in karst areas. Due to the buildup of certain metabolites, they exhibit clear drought resistance. At the same time, water addition during the dry season will also cause a certain stress, affecting the adaptability of plants. These findings have significant ramifications for the management and choice of species in various sea seasons in karst regions.

Adjusting function of camphor on primary metabolism in Cinnamomum camphora stressed by high temperature

Cinnamomum camphora has great economic value for its wide utilization in traditional medicine and furniture material, and releases lots of monoterpenes to tolerate high temperature. To uncover the adjusting function of monoterpenes on primary metabolism and promoting their utilization as anti-high temperature agents, the photosynthetic capacities, primary metabolite levels, cell ultrastructure and associated gene expression were surveyed in C. camphora when it was blocked monoterpene biosynthesis with fosmidomycin (Fos) and fumigated with camphor (a typical monoterpene in the plant) under high temperature (Fos+38 °C+camphor). Compared with the control (28 °C), high temperature at 38 °C decreased the starch content and starch grain size, and increased the fructose, glucose, sucrose and soluble sugar content. Meanwhile, high temperature also raised the lipid content, with the increase of lipid droplet size and numbers. These variations were further intensified in Fos+ 38 °C treatment. Compared with Fos+ 38 °C treatment, Fos+ 38 °C+camphor treatment improved the starch accumulation by promoting 4 gene expression in starch biosynthesis, and lowered the sugar content by suppressing 3 gene expression in pentose phosphate pathway and promoting 15 gene expression in glycolysis and tricarboxylic acid cycle. Meanwhile, Fos+ 38 °C+camphor treatment also lowered the lipid content, which may be caused by the down-regulation of 2 genes in fatty acid formation and up-regulation of 4 genes in fatty acid decomposition. Although Fos+ 38 °C+camphor treatment improved the photosynthetic capacities in contrast to Fos+ 38 °C treatment, it cannot explain the variations of these primary metabolite levels. Therefore, camphor should adjust related gene expression to maintain the primary metabolism in C. camphora tolerating high temperature.

New Insights on Primary and Secondary Metabolite Contents of Seven Italian Wild Food Plants with Medicinal Applications: A Comparative Study.

Wild food plants are widely consumed all over the world and many have both nutritional and therapeutic value due to the presence of biologically active compounds. The present research, for the first time, aims to compare primary and secondary metabolite levels among different plant organs (flower, leaf, stem, root, bark) of seven species (Borago officinalis L., Cynodon dactylon (L.) Pers., Foeniculum vulgare Mill., Hypericum perforatum L., Malva sylvestris L., Sambucus nigra L., Urtica dioica L.) collected in three different Italian regions (Liguria, Tuscany, Apulia). Plant organ samples were extracted with water or 95% (v/v) methanol and liquid fractions were analyzed using spectrophotometric assays. The best results were obtained for Hypericum perforatum L. samples, followed by Sambucus nigra L. and Borago officinalis L. As also confirmed via PCA analysis on normalized data, flower and leaf extracts of all species exhibited higher levels of polyphenols (up to 105.7 mg GA eq/gDW), reducing sugars (up to 389.2 mg GLUC eq/gDW), proteins (up to 675.7 mg BSA eq/gDW) and of antioxidant capacity (up to 263.5 mg AA eq/gDW). No differences among the regions of gathering were detected after spectrophotometric assays, which was confirmed via PCA analysis. These data contribute to further validate the traditionally reported healing effects of these species on human health.

Glucosinolate Catabolism Maintains Glucosinolate Profiles andTransport inSulfur-Starved Arabidopsis.

Glucosinolates (GSLs) are sulfur (S)-rich specialized metabolites present in Brassicales order plants. Our previous study found that GSL can function as a S source in Arabidopsis seedlings via its catabolism catalyzed by two β-glucosidases (BGLUs), BGLU28 and BGLU30. However, as GSL profiles in plants vary among growth stages and organs, the potential contribution of BGLU28/30-dependent GSL catabolism at the reproductive growth stage needs verification. Thus, in this study, we assessed growth, metabolic and transcriptional phenotypes of mature bglu28/30 double mutants grown under different S conditions. Our results showed that compared to wild-type plants grown under -S, mature bglu28/30 mutants displayed impaired growth and accumulated increased levels of GSL in their reproductive organs and rosette leaves of before-bolting plants. In contrast, the levels of primary S-containing metabolites, glutathione and cysteine decreased in their mature seeds. Furthermore, the transport of GSL from rosette leaves to the reproductive organs was stimulated in the bglu28/30 mutants under -S. Transcriptome analysis revealed that genes related to other biological processes, such as ethylene response, defense response and plant response to heat, responded differentially to -S in the bglu28/30 mutants. Altogether, these findings broadened our understanding of the roles of BGLU28/30-dependent GSL catabolism in plant adaptation to nutrient stress.

Metabolic Reprogramming of Barley in Response to Foliar Application of Dichlorinated Functional Analogues of Salicylic Acid as Priming Agents and Inducers of Plant Defence

Designing innovative biological crop protection strategies to stimulate natural plant immunity is motivated by the growing need for eco-friendly alternatives to conventional biocidal agrochemicals. Salicylic acid (SA) and analogues are known chemical inducers of priming plant immunity against environmental stresses. The aim of the study was to study the metabolic reprogramming in barley plants following an application of three proposed dichlorinated inducers of acquired resistance. 3,5-Dichloroanthranilic acid, 2,6-dichloropyridine-4-carboxylic acid, and 3,5-dichlorosalicylic acid were applied to barley at the third leaf stage of development and harvested at 12, 24, and 36 h post-treatment. Metabolites were extracted using methanol for untargeted metabolomics analyses. Samples were analysed by ultra-high performance liquid chromatography coupled to high-definition mass spectrometry (UHPLC-HDMS). Chemometric methods and bioinformatics tools were used to mine and interpret the generated data. Alterations in the levels of both primary and secondary metabolites were observed. The accumulation of barley-specific metabolites, hordatines, and precursors was observed from 24 h post-treatment. The phenylpropanoid pathway, a marker of induced resistance, was identified among the key mechanisms activated by the treatment with the three inducers. No salicylic acid or SA derivatives were annotated as signatory biomarkers; instead, jasmonic acid precursors and derivatives were found as discriminatory metabolites across treatments. The study highlights differences and similarities in the metabolomes of barley after treatment with the three inducers and points to the triggering chemical changes associated with defence and resistance. This report is the first of its kind, and the knowledge acquired provides deeper insight into the role of dichlorinated small molecules as inducers of plant immunity and can be used in metabolomics-guided plant improvement programmes.

Global Change Factors Influence Plant-Epichloë Associations.

There is an increasing interest in determining the influence of global change on plant-microorganism interactions. We review the results of experiments that evaluated the effects of the global change factors carbon dioxide, ozone, temperature, drought, flooding, and salinity on plant symbioses with beneficial Epichloë endophytes. The factors affected the performance of both plants and endophytes as well as the frequency of plants symbiotic with the fungus. Elevated carbon dioxide levels and low temperatures differentially influenced the growth of plants and endophytes, which could compromise the symbioses. Furthermore, we summarise the plant stage in which the effects of the factors were quantified (vegetative, reproductive, or progeny). The factors ozone and drought were studied at all plant stages, but flooding and carbon dioxide were studied in just a few of them. While only studied in response to ozone and drought, evidence showed that the effects of these factors on symbiotic plants persisted trans-generationally. We also identified the putative mechanisms that would explain the effects of the factors on plant-endophyte associations. These mechanisms included the increased contents of reactive oxygen species and defence-related phytohormones, reduced photosynthesis, and altered levels of plant primary metabolites. Finally, we describe the counteracting mechanisms by which endophytes would mitigate the detrimental effects of the factors on plants. In presence of the factors, endophytes increased the contents of antioxidants, reduced the levels of defence-related phytohormones, and enhanced the plant uptake of nutrients and photosynthesis levels. Knowledge gaps regarding the effects of global change on plant-endophyte associations were identified and discussed.

Preharvest Abiotic Stress Affects the Nutritional Value of Lettuce

Lettuce (Lactuca sativa L.) is one of the most consumed leafy green vegetables in the world, and is a good source of important bioactive compounds. However, environmental stress factors, such as salinity or drought, cause physiological and biochemical changes in plants and influence the yields and levels of both primary and secondary metabolites, which drastically changes the nutritional value and quality of the crop. In the present work, six typical Czech cultivars/landraces of various lettuce morphotypes (Altenbursky, Dubacek, Kamenac, Jupiter, Prazan, and Robin) were grown under driven conditions and then analyzed for the content of sugars, fatty acids, amino acids, phenolics, and vitamins. Obtained data were subjected to compositional tables statistical analysis, which provided not only information on general trends in the changes in their nutritional value but also how these changes affected each particular variety. Overall, drought caused the largest relative increase in phenolic compounds and some amino acids. Conversely, drought caused overall the largest relative decrease in vitamin C, but also in fatty acids. In addition, salt stress caused a larger decrease in many metabolites, especially the amino acid arginine, while fatty acids were only slightly increased, together with vitamin E. In addition, the interpretation of data from statistical analysis showed that varieties Prazan and Altenbursky had the least changes in their chemical composition when subjected to drought stress. Again, var. Altenbursky showed the least variability in comparison to other varieties when subjected to salt stress. These findings confirm the fact that landraces and old cultivars do not change their chemical profiles significantly, as is the case for improved cultivars, and they emphasize the need for their cultivation when raising the productivity of staple food crops.

Production of Metabolites in Microalgae Under Alkali Halophilic Growth Medium Using a Dissolved Inorganic Carbon Source

The production of metabolites in microalgae is influenced by extreme cultivation conditions. Bicarbonate is an inorganic carbon source for phototrophic microalgae culturing. In this study, the effect of dissolved inorganic carbon (DIC) (0.4–13 g L−1) on the accumulation of metabolites in Dunaliella tertiolecta biomass is presented. The highest levels of primary metabolites [lipid (239.6 ± 24.3 mg g−1), protein (336.2 ± 47.5 mg g−1)], secondary metabolites [total phenolic (12.8 ± 2.0 mg g−1), total flavonoid (14.4 ± 2.3 mg g−1), total ascorbate (4.7 ± 1.1 mg g−1)], and pigments [chlorophyll (27.2 ± 3.1 mg g−1), carotenoid (2.0 ± 0.1 mg g−1)] were observed when cells were grown with 5.7 g L−1 of DIC (NaHCO3). The highest biomass concentrations (1.5 ± 0.1 g L−1) were obtained for cells grown in a mixture of DIC (4.3 + 1.1 g L−1, NaHCO3 + Na2CO3). This study recommends the optimal levels of bicarbonate carbon of 5.7 g L−1 for maximising the generation of metabolites in the biomass. It also demonstrates that exogenous excessive DIC in the growth medium would be an effective stressor to produce high-value metabolites in Dunaliella or alkali-halophilic strains.Graphical

Effects of geographical location and environmental factors on metabolite content and immune activity of Echinacea purpurea in China based on metabolomics analysis

Echinacea purpurea (L.) Moench, a well-known “immunostimulant” in the West, is one of the most popular plants. The quality and activity of plants are often affected by the environment in that they grow, such as geographical location, climate, and soil. This study reports levels of primary and secondary metabolites and immunomodulatory activity in different parts of E. purpurea from the main regions in which these species are cultivated in China. Metabonomics results showed that E. purpurea in different regions were separated into multiple clusters. Furthermore, the contents of 8 metabolites in E. purpurea differed among regions and parts and differences in immune signaling in macrophages were also observed, including IL-1β, IL-6, TNF-α, and NO. Correlation analyses and redundancy analyses revealed that these differences of E. purpurea were related to geographical location (latitude and longitude) and environmental variables (climate and soil). Precipitation and soil pH were important factors affecting the difference in metabolite contents and immune activity of E. purpurea . The most critical reason for the high immune activity of E. purpurea in Hunan may be due to the high precipitation and slightly acidic pH. The results showed that the metabonomics approach is a powerful strategy for assessing the quality of medicinal plants . Meanwhile, our study was of great significance in site selection and rational cultivation of E. purpurea . • Identification of metabolites in E. purpurea using NMR metabolomic. • Environmental factors had significant effects on the composition of E. purpurea. • High AP and slightly acidic pH may benefit E. purpurea quality. • AP affects E. purpurea quality by affecting chlorogenic acid, choline, 3,5-o-dicaffeoylquinic acid, and coumaric acid levels. • pH affects E. purpurea quality by regulating chicoric acid, acetate, choline, and 1,3-o-dicaffeoylquinic acid levels.

The Effect of Chitosan on Plant Physiology, Wound Response, and Fruit Quality of Tomato.

In agriculture, chitosan has become popular as a metabolic enhancer; however, no deep information has been obtained yet regarding its mechanisms on vegetative tissues. This work was conducted to test the impact of chitosan applied at different plant growth stages on plant development, physiology, and response to wounding as well as fruit shape and composition. Five concentrations of chitosan were tested on tomato. The most effective chitosan doses that increased leaf number, leaf area, plant biomass, and stomatal conductance were 0.75 and 1 mg mL-1. Chitosan (1 mg mL-1) applied as foliar spray increased the levels of jasmonoyl-isoleucine and abscisic acid in wounded roots. The application of this dose at vegetative and flowering stages increased chlorophyll fluorescence (Fv/Fm) values, whereas application at the fruit maturation stage reduced the Fv/Fm values. This decline was positively correlated with fruit shape and negatively correlated with the pH and the content of soluble sugars, lycopene, total flavonoids, and nitrogen in fruits. Moreover, the levels of primary metabolites derived from glycolysis, such as inositol phosphate, lactic acid, and ascorbic acid, increased in response to treatment of plants with 1 mg mL-1- chitosan. Thus, chitosan application affects various plant processes by influencing stomata aperture, cell division and expansion, fruit maturation, mineral assimilation, and defense responses.

Comparative metabolomic analysis reveals the involvement of catechins in adaptation mechanism to cold stress in tea plant (Camellia sinensis var. sinensis)

Cold stress is a major environmental factor that affects tea production and quality. In this study, the global profiles of metabolites in response to cold acclimation (CA) of three tea plant cultivars with contrasting cold tolerances were investigated using UPLC/MS and GC/MS analyses. A total of 167 and 68 metabolites, which were CA responsive and showed differential accumulation in the susceptible and resistant cultivars under CA, were found from UPLC/MS and GC/MS analyses, respectively. The analysis revealed that higher levels of primary metabolites (amino acids, ascorbic acid, intermediates of the tricarboxylic acid cycle, and carbohydrates) were present in the resistant cultivar. Flavonoids (kaempferol, quercetin, myricetin, and catechin), which are secondary metabolites, also showed high accumulation in the cold-resistant cultivar. Accordingly, under CA, catechin component content in the four cold-resistant accessions was higher than that in the three cold-susceptible accessions, indicating that catechins play important roles in the cold response. Moreover, exogenous epigallocatechin gallate (EGCG) application conferred tolerance to freezing stress in tea plants. Tea leaves treated with EGCG exhibited decreased levels of relative electrolyte leakage and malondialdehyde content and increased reactive oxygen species scavenging activity and Fv/Fm under freezing conditions. Expression analysis of cold-regulated genes indicated that EGCG facilitated the transcriptional activation of CsICE1 - CsCBF - CsCOR pathway to improve the freezing tolerance of tea plants. Taken together, the induction of stress tolerance-related metabolites was greater in the cold-resistant cultivar than in susceptible cultivars. This study highlights the important roles of catechins, especially EGCG, in cold tolerance. • The induction of stress tolerance-related metabolites was greater in the cold-resistant tea cultivar. • Flavonoids, including catechins, were important for cold tolerance. • Exogenous EGCG application enhanced the freezing tolerance of tea plants. • EGCG activated the CsICE1 - CsCBF - CsCOR pathway to improve the freezing tolerance of tea plant.

Depicting Precise Temperature and Duration of Vernalization and Inhibiting Early Bolting and Flowering of Angelica sinensis by Freezing Storage.

Angelica sinensis is a perennial rhizomatous herb that is widely used for the treatment of cardio-cerebrovascular diseases, which largely rely on metabolites, such as alkylphthalides, polysaccharides, and ferulic acid. This plant must experience low-temperature vernalization and long-day conditions for the occurrence of early bolting and flowering (EBF) that reduces yield and quality of fleshy root. In current commercial planting, the EBF of more than 40% is mainly attributed to the completion of vernalization of seedlings during overwinter storage. While effects of storage temperatures [vernalization temperature (0–10°C) and freezing temperature (−2 to −12°C)] and seedling sizes on the EBF have been observed in previous studies, the precise vernalization temperature and duration for different size seedlings, the effective freezing storage to avoid vernalization of seedlings, and physiological characteristics have not been systematically investigated. Here, the EBF rate, the anatomical structure of shoot apical meristem (SAM), and physiological characteristics of different size seedlings at different storage temperatures (0, 3, 5, −3, and −5°C) and durations (14–125 d) are reported. The vernalization duration of seedlings was predicated from 57 to 85 d with temperatures ranging from 0 to 5°C based on the linearization regression analysis via Matrix Laboratory software. The EBF can be effectively inhibited by freezing storage. The anatomical structure of SAM, levels of primary metabolites (soluble sugar, starch, amino acid, and protein), and endogenous hormones (GA3, IAA, and ABA), exhibited a dynamical change in the seedlings at different storage temperatures. These findings will provide useful information for predicting the vernalization of seedlings and inhibiting the EBF in large-scale commercial cultivation.

The Lack of Alternative Oxidase 1a Restricts in vivo Respiratory Activity and Stress-Related Metabolism for Leaf Osmoprotection and Redox Balancing Under Sudden Acute Water and Salt Stress in Arabidopsis thaliana.

In plants salt and water stress result in an induction of respiration and accumulation of stress-related metabolites (SRMs) with osmoregulation and osmoprotection functions that benefit photosynthesis. The synthesis of SRMs may depend on an active respiratory metabolism, which can be restricted under stress by the inhibition of the cytochrome oxidase pathway (COP), thus causing an increase in the reduction level of the ubiquinone pool. However, the activity of the alternative oxidase pathway (AOP) is thought to prevent this from occurring while at the same time, dissipates excess of reducing power from the chloroplast and thereby improves photosynthetic performance. The present research is based on the hypothesis that the accumulation of SRMs under osmotic stress will be affected by changes in folial AOP activity. To test this, the oxygen isotope-fractionation technique was used to study the in vivo respiratory activities of COP and AOP in leaves of wild-type Arabidopsis thaliana plants and of aox1a mutants under sudden acute stress conditions induced by mannitol and salt treatments. Levels of leaf primary metabolites and transcripts of respiratory-related proteins were also determined in parallel to photosynthetic analyses. The lack of in vivo AOP response in the aox1a mutants coincided with a lower leaf relative water content and a decreased accumulation of crucial osmoregulators. Additionally, levels of oxidative stress-related metabolites and transcripts encoding alternative respiratory components were increased. Coordinated changes in metabolite levels, respiratory activities and photosynthetic performance highlight the contribution of the AOP in providing flexibility to carbon metabolism for the accumulation of SRMs.

Production of phenylethanoid glycosides under PEG-induced osmotic stress in Scrophularia Striata Boiss. Cell culture in bioreactor

Scrophularia striata Boiss. (Scrophulariaceae) is a significant medicinal and economic plant endemic to Iran. In the research, the effect of osmotic stress on metabolite content during cell growth was studied in S. striata cell culture in a bioreactor system. The high-performance liquid chromatography(HPLC) metabolic profiling showed changes in levels of primary metabolites, containing some amino acids and carbohydrates, secondary metabolites, containing some phenolic acids, flavonoids (diosmin, catechin, rutin,and myricetin), a stilbenoid (resveratrol) and phenylethanoid glycosides (acteoside and echinacoside) in response to elicitation with polyethylene glycol (PEG) 6000. Content of acteoside was significantly induced and was achieved by 6.38 folds compared to the control. This approach can be used to improve mass production of acteoside from S. striata cell culture in industrial bioreactors. The two-dimensional electrophoresis (2-DE) study showed that elicitation of cell culture with PEG 6000 led to modification of proteome profile. In PEG-treated cells, 45 spots were upregulated and 47 spots were downregulated (fold>2 and p<0.05) compared to control and 4 protein spots were determined by MALDI-ToF MS. These proteins corresponded to Glyceraldehyde 3-phosphate dehydrogenase, Cinnamoyl alcohol dehydrogenase, Manganese superoxide dismutase, and Flavodoxin-like quinone reductase 1, expressions of which were associated with stress condition.