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Unveiling physiological responses and modulated accumulation patterns of specialized metabolites in Mentha rotundifolia acclimated to sub-tropical environment
Abstract
Mints are aromatic plants of Lamiaceae, globally known for the phytochemical-rich essential oils. Most of the cultivated mints are menthol-rich, whereas spearmint being the only dominant carvone-rich species. In this study, another carvone-rich mint Mentha rotundifolia (L.) Huds., a native of temperate region was assessed for its acclimation in sub-tropical environment to see any possible changes in specialized metabolite accumulation. Plants grown under open environment was compared with glasshouse grown plants where, temperature, humidity and photoperiods were uniformly maintained. Thickened leaves with increased cuticular wax load (2.82 folds) and anthocyanin accumulation (202.97 µg/g) in the widened stems were observed in plants grown in open environment, while higher chlorophyll contents were exhibited by the glasshouse-grown plants. Enhanced antioxidant capacity in open environment, correlated with elevated concentration (86.4% increase for caffeic acid) of wall-bound phenolics was observed. Increased proline, hydrogen peroxide and malondialdehyde contents in open environment indicated the plant’s ability to cope up with abiotic stress. Higher amounts of terpenes like (-)-carvone (2.68 folds) and D-limonene (1.35 folds) were found in both internal volatile pool and essential oil of glasshouse-grown plants. Histochemical study of glandular trichomes also supported this finding. In conclusion, glasshouse-grown plants showed relatively better growth and higher terpene contents, nevertheless the plant survived well in warmer environment, with increased antioxidant capacities and phenolic contents. Future study includes mass propagation of this species in different geographical locations with distinct climatic variations to determine the suitable sub-tropical locations for cultivation as a potential alternative to spearmint for commercial-scale (-)-carvone production.
... Similarly, Angelica glauca, an endangered high-altitude plant, regulates MEP-derived monoterpenes (limonene and phellandrene), known for their antimicrobial and adaptogenic properties (Kumar et al. 2023). Mentha rotundifolia, growing at high altitudes, increases monoterpene production via the MEP pathway under cold stress, with menthol and pulegone aiding temperature regulation (Chatterjee and Mitra 2024). Rheum palmatum, adapted to the Tibetan Plateau, produces anthraquinones (chrysophanol and emodin) through MEP-shikimate pathway crosstalk, important for stress mitigation and UV protection (Zhang et al. 2024). ...
High altitude conditions pose a significant challenge to all earth’s inhabitants including flora. Low atmospheric pressure (thin air), intense ultraviolet (UV) light, and ultra-low temperatures combine to cause oxidative stress in plants. In these abiotic stress conditions, plants exhibit various ecophysiological, morphological, and biochemical adaptations to cope with stress. Morphologically, plants may develop smaller, thicker leaves with protective trichomes or waxy cuticles against intense UV radiation, and minimize water loss in the thin, dry air. However biochemically, plants increase the production of UV-absorbing compounds like flavonoids and phenolic acids along with antioxidant enzymes for neutralizing reactive oxygen species (ROS). To protect against these stress conditions plants start producing specialized metabolites, i.e., isoprenoids, phenolic acids, flavonoids, sterols, carotenoids, etc. The production of these specialized metabolites occurs through MEP (methylerythritol phosphate) and MVA (mevalonic acid) pathways. Although, this article aims to review the scientific complexities of high-altitude plants by providing an in-depth explanation of the MEP pathway, including its regulation, sources and causes of oxidative stress in plants, functions and roles of isoprenoids in stress tolerance, and the adaptation strategies that support alpine plant survival and acclimation. The MEP pathway’s products, several carotenoids, viz., phytoene, lycopene, β-carotene, etc., and terpenoids, viz., geraniol, citral, phytol, etc., act as potent scavengers of ROS, providing defense against oxidative damage. Also, phytohormones, viz., abscisic acid, salicylic acid, and jasmonic acid play crucial roles in modulating plant responses to oxidative stress. To date, little scientific literature is available specifically on high-altitude plants with respect to MEP pathway and oxidative stress management. Understanding the interaction between the MEP pathway and oxidative stress in high-altitude plants can provide insight into the implications for improving crop resilience and producing bioactive chemicals with potential human health benefits.
Science Synergy: Exploring Interdisciplinary Frontiers," a comprehensive
journey into the dynamic and interconnected world of scientific disciplines. This book is
born out of a deep appreciation for the remarkable progress made possible when
diverse fields of study converge to address complex challenges and illuminate new
pathways for discovery.
The essence of scientific inquiry lies in its ever-evolving nature, driven by curiosity and
a relentless pursuit of knowledge. In recent decades, the boundaries that once
delineated individual fields have become increasingly porous, fostering a fertile ground
for interdisciplinary collaboration. This synergy has catalyzed groundbreaking
advancements, from revolutionary medical therapies to sustainable environmental
solutions and cutting-edge technological innovations.
"Science Synergy" aims to celebrate and elucidate these collaborative efforts,
showcasing how the fusion of disciplines can lead to a holistic understanding of the
natural world and the solutions we seek. Each chapter delves into different realms
where interdisciplinary approaches have yielded transformative results, drawing
connections between seemingly disparate fields such as biology and engineering,
physics and medicine, or computer science and environmental science.
The inspiration for this book stems from the recognition that the most pressing
problems of our time—climate change, global health crises, technological ethics, and
more—cannot be effectively addressed through isolated efforts. By highlighting case
studies, pioneering research, and visionary projects, we hope to inspire a new
generation of scientists, researchers, and thinkers to embrace the power of
collaboration and to think beyond traditional boundaries.
As you embark on this exploration of interdisciplinary frontiers, we invite you to
appreciate the richness and diversity of scientific inquiry. May this book serve as a
testament to the profound impact of collaborative efforts and ignite a passion for
integrative thinking in all who read it.
We extend our deepest gratitude to the contributors, researchers, and visionaries
whose work has shaped this book. Their dedication and innovative spirit are the true
driving forces behind the stories and insights presented here.
This study investigates the impact of anthocyanin treatment on rice plants under drought stress, focusing on phenotypic, molecular, and biochemical responses. Anthocyanin were treated to one month old plants one week before the droughtexposure. Drought stress was imposed by using 10% polyethylene glycol (PEG 6000). Anthocyanin-treated plants exhibited significant enhancements in various traits, including growth parameters and reproductive characteristics, under normal conditions. When subjected to drought stress, these plants displayed resilience, maintaining or improving essential morphological and physiological features compared to non-treated counterparts. Notably, anthocyanin application mitigated drought-induced oxidative stress, as evidenced by reduced levels of reactive oxygen species (ROS) and lipid membrane peroxidation. The study also elucidates the regulatory role of anthocyanins in the expression of flavonoid biosynthetic genes, leading to increased levels of key secondary metabolites. Furthermore, anthocyanin treatment influenced the levels of stress-related signaling molecules, including melatonin, proline, abscisic acid (ABA), and salicylic acid (SA), contributing to enhanced stress tolerance. The enzymatic activity of antioxidants and the expression of drought-responsive genes were modulated by anthocyanins, emphasizing their role in antioxidant defense and stress response. Additionally, anthocyanin treatment positively influenced macronutrient concentrations, particularly calcium ion (Ca⁺), potassium ion (K⁺), and sodium ion (Na⁺), essential for cell wall and membrane stability. The findings collectively highlight the multifaceted protective effects of anthocyanins, positioning them as potential key players in conferring resilience to drought stress in rice plants. The study provides valuable insights into the molecular and physiological mechanisms underlying anthocyanin-mediated enhancement of drought stress tolerance, suggesting promising applications in agricultural practices for sustainable crop production.
Plants are constantly exposed to a wide array of complex interactions involving various environmental factors, leading to disruptions in their metabolic processes and incurring physiological costs when faced with biotic and abiotic stress. In response to these stimuli, plants have developed diverse signaling mechanisms to adapt to the prevailing conditions. Plants equipped with different signaling pathways undergo changes at the transcriptomic and metabolic level to survive stress stimuli. The signaling pathways are divided into four major subsections: signal perception, signal transduction, regulation of gene expression and physiological responses. Transcription factors (TFs) play a crucial role in the organization of defense mechanisms by regulating downstream gene expression. Primary metabolites (PMs) and Secondary metabolites (SMs) represent fundamental compounds involved in these plant response mechanisms. These plant extracts are a promising method of increasing the tolerance of plants to environmental stresses and can be used as biostimulants. This review aimed to elucidate the contributions of PMs and SMs in plant reactions, as well as their biosynthesis pathways. Additionally, the interplay between these compounds was discussed. The molecular physiology of plant responses to environmental stimuli via signaling pathway was described in this research. Ultimately, plant metabolites were introduced as bio stimulants that can mitigate the adverse effects of various biotic and abiotic stresses.
Background
Here, we investigated the underlying transcriptional-level evidence behind phytochemical differences between two metabolically extreme genotypes of Thymus daenensis. The genotypes ‘Zagheh-11’ (thymol/carvacrol type, poor in essential oil [EO] [2.9%] but rich in triterpenic acids) and ‘Malayer-21’ (thymol type and rich in EO [3.8%]) were selected from an ongoing breeding program and then clonally propagated for further experimental use.
Materials and methods
GC-MS, GC-FID, and HPLC-PDA were utilized to monitor the fluctuation of secondary metabolites at four phenological stages (vegetative, bud burst, early, and full-flowering stages). The highest phytochemical divergence was observed at early flowering stage. Both genotypes were subjected to mRNA sequencing (approximately 100 million paired reads) at the aforementioned stage. The expression patterns of four key genes involved in the biosynthesis of terpenoids were also validated using qRT-PCR.
Results
Carvacrol content in ‘Zagheh-11’ (26.13%) was approximately 23 times higher than ‘Malayer-21’ (1.12%). Reciprocally, about 10% higher thymol was found in ‘Malayer-21’ (62.15%). Moreover, the concentrations of three major triterpenic acids in ‘Zagheh-11’ were approximately as twice as those found in ‘Malayer-21’. Transcriptome analysis revealed a total of 1840 unigenes that were differentially expressed, including terpene synthases, cytochrome P450, and terpenoid backbone genes. Several differentially expressed transcription factors (such as MYB, bZIP, HB-HD-ZIP, and WRKY families) were also identified. These results suggest that an active cytosolic mevalonate (MVA) pathway may be linked to higher levels of sesquiterpenes, triterpenic acids, and carvacrol in ‘Zagheh-11’. The chloroplastic pathway of methyl erythritol phosphate (MEP) may have also contributed to a higher accumulation of thymol in Malayer-21. Indeed, ‘Zagheh-11’ showed higher expression of certain genes (HMGR, CYP71D180, β-amyrin 28-monooxygenase, and sesquiterpene synthases) in the MVA pathway, while some genes in the MEP pathway (including DXR, ispG, and γ-terpinene synthase) were distinctly expressed in Malayer-21. Future efforts in metabolic engineering of MVA/MEP pathways may benefit from these findings to produce increased levels of desired secondary metabolites at commercial scale.
Global agricultural production must double by 2050 to meet the demands of an increasing world human population but this challenge is further exacerbated by climate change. Environmental stress, heat, and drought are key drivers in food security and strongly impacts on crop productivity. Moreover, global warming is threatening the survival of many species including those which we rely on for food production, forcing migration of cultivation areas with further impoverishing of the environment and of the genetic variability of crop species with fall out effects on food security. This review considers the relationship of climatic changes and their bearing on sustainability of natural and agricultural ecosystems, as well as the role of omics-technologies, genomics, proteomics, metabolomics, phenomics and ionomics. The use of resource saving technologies such as precision agriculture and new fertilization technologies are discussed with a focus on their use in breeding plants with higher tolerance and adaptability and as mitigation tools for global warming and climate changes. Nevertheless, plants are exposed to multiple stresses. This study lays the basis for the proposition of a novel research paradigm which is referred to a holistic approach and that went beyond the exclusive concept of crop yield, but that included sustainability, socio-economic impacts of production, commercialization, and agroecosystem management.
The year 2024 marks 70 years since the general outline of the carbon pathway in photosynthesis was published. Although several alternative pathways are now known, it is remarkable how many organisms use the reaction sequence described 70 yrs ago, which is now known as the Calvin–Benson cycle or variants such as the Calvin–Benson–Bassham cycle or Benson–Calvin cycle. However, once the carbon has entered the Calvin–Benson cycle and is converted to a 3-carbon sugar, it has many potential fates. This review will examine the last stages of photosynthetic metabolism in leaves. In land plants, this process mostly involves the production of sucrose provided by an endosymbiont (the chloroplast) to its host for use and transport to the rest of the plant. Photosynthetic metabolism also usually involves the synthesis of starch, which helps maintain respiration in the dark and enables the symbiont to supply sugars during both the day and night. Other end products made in the chloroplast are closely tied to photosynthetic CO2 assimilation. These include serine from photorespiration and various amino acids, fatty acids, isoprenoids, and shikimate pathway products. I also describe 2 pathways that can short circuit parts of the Calvin–Benson cycle. These final processes of photosynthetic metabolism play many important roles in plants.
Salinity stress is a major abiotic factor that affects medicinal plant growth, performance, and secondary compounds. Malva parviflora L. and Rumex dentatus L. plants were collected from three habitats in the northeastern Nile Delta governorates of Damietta and El-Dakahlia. Conductivity (salinity) classified the habitats as mesophytic, moderately saline, and saline. Chemical and physical soil characteristics varied by habitat. Results show that M. parviflora L. and R. dentatus L. had high soluble sugars, total carbohydrates, electrolyte leakage, and proline in the saline habitat. In contrast, mesophytic habitats showed low content. In addition, R. dentatus L. had more antioxidant enzymes and elements in saline habitats than in mesophytic habitats. In saline habitats, M. parviflora L. and R. dentatus L. were characterized by more calcium and sodium increase than mesophytic habitats. Moreover, R. dentatus L. had more phenols, alkaloids, flavonoids, anthocyanin, and tannins under saline conditions than M. parviflora . Meanwhile, in the saline habitat, plant hormones, i.e., indole acetic acid and gibberellic acid, decreased significantly in both M. parviflora and R. dentatus than in the mesophytic habitat. Scanning Electron Microscopy (SEM) of the tested plants showed the highest stomatal frequency and area on the lower surface of mesophytic plant leaves compared to either its upper surface or both leaf surfaces in saline habitat. Hence, it can be concluded that R. dentatus plant can mitigate the negative effects of salinity by improving the qualitative and quantitative performance under salinity stress more than M. parviflora plant.
Daylength, a seasonal and latitudinal variable, exerts a substantial impact on plant growth. However, the relationship between daylength and growth is non-proportional, suggesting the existence of adaptive mechanisms. Thus, our study aimed to comprehensively investigate the adaptive strategies employed by plants in response to daylength variation. We grew false flax (Camelina sativa) plants, a model oilseed crop, under long day (LD) and short day (SD) conditions and used growth measurements, gas exchange measurements, and isotopic labeling techniques, including ¹³C-, ¹⁴C-, and ²H2O, to determine responses to different daylengths. Our findings revealed that daylength influences various growth parameters, photosynthetic physiology, carbon partitioning, metabolic fluxes, and metabolite levels. SD plants employed diverse mechanisms to compensate for reduced CO2 fixation in the shorter photoperiod. These mechanisms included enhanced photosynthetic rates and reduced respiration in the light (RL), leading to increased shoot investment. Additionally, SD plants exhibited reduced rates of the glucose 6-phosphate (G6P) shunt and greater partitioning of sugars into starch, thereby sustaining carbon availability during the longer night. Isotopic labeling results further demonstrated substantial alterations in the partitioning of amino acids and TCA cycle intermediates between rapidly and slowly turning over pools. Overall, the results point to multiple developmental, physiological, and metabolic ways in which plants adapt to different daylengths to maintain growth.
Citation: Hubert, C.; Tsiaparas, S.; Kahlert, L.; Luhmer, K.; Moll, M.D.; Passon, M.; Wüst, M.; Schieber, A.; Pude, R. Effect of Different Postharvest Methods on Essential Oil Content and Composition of Three Mentha Genotypes. Horticulturae 2023, 9, 960. https://doi.org/10.3390/ horticulturae9090960 Academic Editor: Michailidis Michail Abstract: Mentha sp. is commonly used for essential oil (EO) extraction and incorporated in multiple products of food and pharmaceutical industries. Postharvest management is a key factor in line of production to preserve quality-determining plant ingredients. This study focused on the effects of two different postharvest processes on EO content and the composition of three different Mentha genotypes (Mentha × piperita 'Multimentha', Mentha × piperita 'Fränkische Blaue' and Mentha rotundifolia 'Apfelminze'). They were cultivated under greenhouse conditions. One postharvest treatment consisted of drying Mentha as whole plant after harvesting and later separating leaves from stems. In the second treatment, leaves were separated from stems directly after harvesting and then dried. EO content was determined by steam distillation and composition of EO was characterized by GC/MS analysis. Key findings of the study are that the postharvest processing treatments had no significant influence on the content or composition of the EO. Only the genotype 'Fränkische Blaue' showed a significantly higher EO content in the dry separated treatment at the third harvest (2.9 ± 0.15 mL/100 g DM (sD)) than separated fresh (2.4 ± 0.24 mL/100 g DM (sF)). However, genotype selection and harvest time had a clear impact on EO content and composition.
Hidden hunger, also known as micronutrient deficiency, is a form of undernutrition, which is exacerbated when food security is fragile. However, the amount of phytonutrients in the diet can be increased by using underutilized species, such as fresh mint greens (Mentha). These plants have a high biological value due to the high content of biologically active substances. Plants of the genus Mentha, however, differ significantly in their chemical composition and, thus, nutritional value. The main objective of this study was to evaluate the content of phytonutrients in different Ukrainian species of mint: peppermint (Mentha piperita), horsemint (Mentha longifolia L.), silver-leaved horsemint (Mentha longifolia S.), and spearmint (Mentha spicata L.), and to determine their stability after drying and freezing. After studying the chemical composition of fresh, dried, and frozen plants of these species, it was established that Ukrainian mint species offer a robust set of phytonutrients and can be used as ingredients of the so-called “functional foods.” The biologically active substances in mint are concentrated during drying. Moreover, such raw materials are easily stored and used as an ingredient. However, the losses of ascorbic acid due to drying mint reach 70%; of carotenoids—approximately 10–15%; of chlorophylls—21–38%; and of phenols—19–29%. Peppermint and spearmint were observed to have higher stability of biologically active compounds. As for the freezing, the best stability of the chemical composition was demonstrated by field mint and spearmint samples. Therefore, a targeted selection of mint types and varieties prior to processing will allow preserving maximal preservation of a maximum amount of biologically active substances, increasing the content of phytonutrients in finished products, and preventing the development of hidden hunger.
Light emitting diodes (LEDs) as an alternative light source for plants had shown to enhance the plant material quality. Indian borage or Plectranthus amboinicus (Lour.) Spreng, a medicinal herb produces carvacrol as the major volatile organic compound (VOC). Histolocalization of VOCs and expression pattern of the terpenoid biosynthesis genes after spectral light treatment is not yet reported in P. amboinicus. This work investigated the morpho-physiological, biochemical and transcriptional responses towards red, green, blue, warm white and red-blue (RB, 1:1) LEDs treatment at 40 ± 5 μmol m⁻² s⁻¹ light intensity after 40 days. Maximal growth index (GI), leaf fresh weight and dry weight were obtained in RB (1:1) treated plants. There was one-fold increase in phenolics content and 2.5-fold increase in antioxidant activity in comparison to warm white. High quantity of terpenes and phenolics deposition were observed in the glandular trichomes of RB (1:1). Maximum carvacrol accumulation (14.45 µmol g⁻¹ FW) was also detected in RB (1:1). The transcript levels of early terpene biosynthesis genes PaDXS, PaDXR, PaHMGR and cytochrome P450 monooxygenase genes, PaCYP1 and PaCYP9 were highly upregulated in RB (1:1) and green. The overall results suggest RB (1:1) as the better lighting option amongst the studied spectral lights for obtaining maximum phytochemicals in P. amboinicus. Work is being continued with different spectral ratios of red and blue LED lights to maximize phytochemical accumulation, the outcome of which will be reported elsewhere in near future.
The potential applications of the genus Mentha as natural pesticides and environmentally friendly postharvest treatments for agricultural products in sustainable agriculture are reviewed here. The non-commercialized Mentha species in Greece and the rest of the world are presented, and the possibility of their exploitation is discussed. Recent developments in successive methods of application—i.e., the formulation of Mentha extracts/oils in eco-friendly pesticides, fumigation, and the assessment of performance in field trials—are also reported. Several studies have shown that Mentha species in various forms (e.g., essential oil (EO), aqueous extract, fresh or dried plant material, compost, etc.), or in different cropping systems (e.g., crop rotation, intercropping system/cover crop, cultivation and incorporation as green manure) offer the potential to be used in agriculture, with the goal of managing plant pathogens (bacteria and fungi), animal pests (insects, acarines, and nematodes), weeds, and for the improvement of soil quality and productivity as well. Finally, several studies are presented concerning the enhancement of Mentha EOs effectiveness in agriculture, and to also overcome the limitations of their nature (being unstable when exposed to light and oxygen), by using a combination of EOs, or by developing novel formulations (microencapsulation). Taking into consideration all the abovementioned findings, it is evident that Mentha species could be used in sustainable agricultural systems for integrated pest management. This can be achieved utilizing them either directly as a crop, green manure, or compost, or indirectly by developing natural pesticides based on their EOs or extracts. Nonetheless, further field experiments must be conducted, to confirm the efficacy of various formulas on pests under crop conditions.
Introduction
Oxidative stress plays a causal role in neurodegenerative diseases. The aim of this study is to evaluate the antioxidant and neuroprotective effects of Mentha rotundifolia (L.) Huds (M. rotundifolia), a widely used Moroccan plant in traditional medicine.
Methods
The chemical composition of M. rotundifolia aqueous extract was analyzed by liquid chromatography coupled to mass spectrometry (LC-MS). 2,2-diphenyl 1-picrylhydrazyl (DPPH) and 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) assays were used to assess its in vitro antioxidant activity. H2O2 was utilized to induce oxidative stress and neurotoxicity in vivo. Behavioral changes were evaluated using Open Field, Y-maze and Rotarod tests. Hyperalgesia was assessed using the tail immersion test.
Results and discussion
The LC-MS/MS analysis revealed high content of kaempferol glucuronide (85%) at the extract. IC50 values of the DPPH and ABTS were 26.47 and 41.21 μg/mL, respectively. Pre-treatments with M. rotundifolia extract attenuated the behavioral changes induced by H2O2. In addition, the latency of tail withdrawal increased significantly in the treated groups suggesting central analgesic effect of M. rotundifolia extract. Moreover, the extract attenuated the deleterious effects of H2O2 and improved all liver biomarkers. The obtained results suggested that M. rotundifolia had remarkable antioxidant and neuroprotective effects and may prevent oxidative stress related disorders.
Several environmental stresses, including biotic and abiotic factors, adversely affect the growth and development of crops, thereby lowering their yield. However, abiotic factors, e.g., drought, salinity, cold, heat, ultraviolet radiations (UVr), reactive oxygen species (ROS), trace metals (TM), and soil pH, are extremely destructive and decrease crop yield worldwide. It is expected that more than 50% of crop production losses are due to abiotic stresses. Moreover, these factors are responsible for physiological and biochemical changes in plants. The response of different plant species to such stresses is a complex phenomenon with individual features for several species. In addition , it has been shown that abiotic factors stimulate multi-gene responses by making modifications in the accumulation of the primary and secondary metabolites. Metabolomics is a promising way to interpret biotic and abiotic stress tolerance in plants. The study of metabolic profiling revealed different types of metabolites, e.g., amino acids, carbohydrates, phenols, polyamines, terpenes, etc, which are accumulated in plants. Among all, primary metabolites, such as amino acids, carbohydrates , lipids polyamines, and glycine betaine, are considered the major contributing factors that work as osmolytes and osmoprotectants for plants from various environmental stress factors. In contrast, plant-derived secondary metabolites, e.g., phenolics, terpenoids, and nitrogen-containing compounds (alkaloids), have no direct role in the growth and development of plants. Nevertheless, such metabolites could play a significant role as a defense by protecting plants from biotic factors such as herbivores, insects, and pathogens. In addition, they can enhance the resistance against abiotic factors. Therefore, metabolomics practices are becoming essential and influential in plants by identifying different phytochemicals that are part of the acclimation responses to various stimuli. Hence, an accurate metabolome analysis is important to understand the basics of stress physiology and biochemistry. This review provides insight into the current information related to the impact of biotic and abiotic factors on variations of various sets of metabolite levels and explores how primary and secondary metabolites help plants in response to these stresses.
The general aim of this work was to compare the leaf-level responses of different protective components to water deficit and high temperatures in Quercus cerris L. and Quercus robur L. Several biochemical components of the osmotic adjustment and antioxidant system were investigated together with changes in hormones. Q. cerris and Q. robur seedlings responded to water deficit and high temperatures by: (1) activating a different pattern of osmoregulation and antioxidant mechanisms depending on the species and on the nature of the stress; (2) upregulating the synthesis of a newly-explored osmoprotectant, dimethylsulphoniopropionate (DMSP); (3) trading-off between metabolites; and (4) modulating hormone levels. Under water deficit, Q. cerris had a higher antioxidant capacity compared to Q. robur, which showed a lower investment in the antioxidant system. In both species, exposure to high temperatures induced a strong osmoregulation capacity that appeared largely conferred by DMSP in Q. cerris and by glycine betaine in Q. robur. Collectively, the more stress-responsive compounds in each species were those present at a significant basal level in non-stress conditions. Our results were discussed in terms of pre-adaptation and stress-induced metabolic patterns as related to species-specific stress tolerance features.
In recent years, the study of aromatic plants has seen an increase, with great interest from industrial, academic, and pharmaceutical industries. Among plants attracting increased attention are the Mentha spp. (mint), members of the Lamiaceae family. Mint essential oils comprise a diverse class of molecules known as terpenoids/isoprenoids, organic chemicals that are among the most diverse class of naturally plant derived compounds. The terpenoid profile of several Mentha spp. is dominated by menthol, a cyclic monoterpene with some remarkable biological properties that make it useful in the pharmaceutical, medical, cosmetic, and cleaning product industries. As the global market for Mentha essential oils increases, the desire to improve oil composition and yield follows. The monoterpenoid biosynthesis pathway is well characterised so metabolic engineering attempts have been made to facilitate this improvement. This review focuses on the Mentha spp. and attempts at altering the carbon flux through the biosynthetic pathways to increase the yield and enhance the composition of the essential oil. This includes manipulation of endogenous and heterologous biosynthetic enzymes through overexpression and RNAi suppression. Genes involved in the MEP pathway, the menthol and carvone biosynthetic pathways and transcription factors known to affect secondary metabolism will be discussed along with non-metabolic engineering approaches including environmental factors and the use of plant growth regulators.
The purpose of this study was to chemically compare samples of Mentha spicata (marketing byproducts, production byproducts, and export material), cultivated in the open field and under greenhouse, using an integrated approach by HPLC/DAD and GC/MS analysis. The presence of phenolic compounds was higher in the marketing byproducts cultivated in the open field. Marketing byproducts also had the highest amount of carvone. For this reason, this byproduct was selected as a candidate for the development of natural ingredients. With the best selected material, the optimization of simultaneous high-intensity ultrasound-assisted extraction processes was proposed for the recovery of the compounds of interest. This extraction was defined by Peleg’s equation and polynomial regression analysis. Modeling showed that the factors amplitude, time, and solvent were found to be significant in the recovery process (p < 0.005). The maximum amount of compounds was obtained using 90% amplitude for 5 min and ethanol/water mixture (80:20) for extraction to simultaneously obtain phenolic and terpenoid compounds. This system obtained the highest amount of monoterpenoid and sesquiterpenoid compounds from the essential oil of M. spicata (64.93% vs. 84.55%). Thus, with an efficient and eco-friendly method, it was possible to optimize the extraction of compounds in M. spicata as a starting point for the use of its byproducts.
Mentha spicata L. is cultivated for its essential oil which has various industrial uses. There are several species of Mentha genus but M. spicata is the only one which is rich in carvone. The present study was carried out at Central Institute of Medicinal and Aromatic Plants (CIMAP), Research Centre, Pantnagar in 2020 to evaluate the yield potential and essential oil quality of five spearmint cultivars grown in subtropical condition of Uttarakhand, so that farmers could select, choose and cultivate the right cultivar to get maximum benefits. CIM-Mohak and MSS-5 showed significant higher yield (herb yield, essential oil yield) i.e. 124.10 and 116.20 q/ha and 68.88 and 70.58 kg/ ha, respectively. The analysis of essential oils from five spearmint cultivars revealed that limonene was more in Neer kalka (35.1%) and carvone was more in Arka (64.35%) but cultivars CIM-Mohak and MSS-5 had almost same concentration of carvone and limonene. The study concludes that CIM-Mohak and MSS-5 can be grown for spearmint cultivation in subtropical conditions for higher returns.
Trichomes and cuticles are key protective epidermal specializations. This review highlights the genetic interplay existing between trichome and cuticle formation in a variety of species. Controlling trichome development, the biosynthesis of trichome‐derived specialized metabolites as well as cuticle biosynthesis and deposition can be viewed as different aspects of a common defensive strategy adopted by plants to protect themselves from environmental stresses. Existence of such interplay is based on the mining of published transcriptomic data as well as on phenotypic observations in trichome or cuticle mutants where the morphology of both structures often appear to be concomitantly altered. Given the existence of several trichome developmental pathways depending on the plant species and the types of trichomes, genetic interactions between cuticle formation and trichome development are complex to decipher and not easy to generalize. Based on our review of the literature, a schematic overview of the gene network mediating this transcriptional interplay is presented for two model plant species: Arabidopsis thaliana and Solanum lycopersicum. In addition to fundamental new insights on the regulation of these processes, identifying key transcriptional switches controlling both processes could also facilitate more applied investigations aiming at improving much desired agronomical traits in plants.
Simple Summary
Water scarcity is one of the main threats for the future of agriculture and the worldwide population. Improving the ability of crop species to grow and survive with less water is therefore essential. A fundamental goal of most scientists working in this area is to understand the mechanisms plants must potentiate to better survive under reduced water availability. Here we provide evidence that accumulation of anthocyanins, a major player in red leaf color, may fulfil two important functions. First, they serve as a filter for protecting plants against excessive sunlight; second, they control plant water loss by reducing stomatal transpiration and density. Since excessive sunlight and temperature, associated with climate change, come along with water shortage, these pigments may protect and help plants to survive throughout hot and dry seasons. Our results have important social implications for people living in areas where rising temperatures and water shortages are already critical. Breeding programs to obtain crops with these stress tolerance traits can be specifically designed for these environments.
Abstract
Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress.
Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans.
Main conclusion
Three types of the glandular trichomes are developed on the flowers and leaves of Millingtonia hortensis. Morphology, cell ultrastructure and content of the volatile compounds are specific to each trichome type.
Abstract
The aim of this study was to characterize the structural and histochemical features of the glandular trichomes (GTs) of two types localized on the different flower parts and leaves in Millingtonia hortensis, as well as to identify the composition of the internal pool of metabolites. The peltate GTs are most common; they are founded on peduncle, calyx, ovary, and leaves. GTs consist of 12–24-cell disk-shaped head and a single-celled neck. The capitate GTs are located on corolla tube and have four to eight-cell head, single-celled neck and a wide multicellular stalk. A series of histochemical reactions and fluorescent microscopy revealed the various substances in the chemical composition of GTs. Acid polysaccharides are predominately identified in the capitate trichomes of the corolla tube and peltate trichomes of calyx, terpenes present in larger quantity in the trichomes of the corolla tube and ovary, whilst phenolic substances prevail in the trichomes of the calyx and ovary. GTs of each type are characterized by specific ultrastructural traits. Smooth endoplasmic reticulum (SER) and leucoplasts prevail in the peltate trichomes of peduncle, calyx and ovary; Golgi apparatus is the common organelle in the capitate trichomes of the corolla tube and peltate trichomes of calyx; the huge aggregates of the RER cisterns there are in cytoplasm of all leaf trichomes. Synthesized secretion accumulates in the subcuticular cavity of all GTs except the leaf peltate trichomes. In the trichomes of the leaves secretion is stored in the thick upper cell wall with the wide cutinized layer. For the first time content of the internal pool of metabolites from the flowers and leaves was identified by GC–MS. Seventeen compounds, including alcohols, fatty acid derivatives, monoterpenes, sesquiterpenes, and benzenoids were identified. 1-octen 3-ol, 3-carene, methyl salicylate, p-hydroxybenzeneethanol and 1-hydroxy-2,4-di-tertbutyl-benzene were the main compounds of the flower scent. We consider GTs of the reproductive organs in M. hortensis synthesizing acid polysaccharides and volatile compounds as secretory structures attracting of pollinators, whereas the leaf peltate trichomes accumulating predominately non-volatile phenols, protect young vegetative shoots against small herbivorous insects and pathogens.
Plants produce a large variety of natural products. Terpenes seem to be the largest and the most important group of secondary metabolites in conifer trees. They protect the plant from invading pathogens and herbivores by representing constitutive or induced defense mechanisms. Moreover, antioxidant properties of some terpenes have also been shown, suggesting their role in overcoming oxidative stress provoked by internal and external stimuli. The abiotic and biotic stress factors such as drought, temperature fluctuations, air and soil pollution or pathogen attack rearrange the biosynthesis and emission of terpenes, however the response may depend on the stressor type and stress intensity. Although the general composition of terpenes is characteristic for each species, it has been shown that it can even differ between two individual trees. Reaching for the available literature data, the review is focused on systematizing the observed changes in terpene quantity and quality in the three most important forest-forming conifer genera of European temperate climate zone – pine (Pinus sp.), spruce (Picea sp.) and fir (Abies sp.). Moreover, in view of progressive climate change, the study emphasize a complex function of these interesting compounds in trees including interplant signaling in forest communities.
Glandular trichomes (GTs) are defensive structures that produce and accumulate specialized metabolites and protect plants against herbivores, pathogens, and abiotic stress. GTs have been extensively studied in angiosperms for their roles in defense and biosynthesis of high-value metabolites. In contrast, trichomes of gymnosperms have been described in fossilized samples, but have not been studied in living plants. Here, we describe the characterization of GTs on young stems of a hybrid white spruce. Metabolite and histological analysis of spruce GTs support a glandular function with accumulation of a diverse array of mono-, sesqui- and diterpenes including diterpene methylesters. Methylated diterpenes have previously been associated with insect resistance in white spruce. Headspeace analysis of spruce GTs showed a profile of volatiles dominated by monoterpenes and a highly diverse array of sesquiterpenes. Spruce GTs appear early during shoot growth, prior to the development of a lignified bark and prior to accumulation of terpenes in needles. Spruce GTs may provide an early, terpene-based chemical defense system at a developmental stage when young shoots are particularly vulnerable to foliage and shoot feeding insects, and before the resin duct system characteristic of conifers has fully developed.
Sample preparation including dehydration and drying of samples is the most intricate part of scanning electron microscopy. Most current sample preparation protocols use critical-point drying with liquid carbon dioxide. Very few studies have reported samples that were dried using chemical reagents. In this study, we used hexamethyldisilazane, a chemical drying reagent, to prepare plant samples. As glandular trichomes are among the most fragile and sensitive surface structures found on plants, we used Millingtonia hortensis leaf samples as our study materials because they contain abundant glandular trichomes. The results obtained using this new method are identical to those produced via critical-point drying.
Pathogens hitting the plant cell wall is the first impetus that triggers the phenylpropanoid pathway for plant defense. The phenylpropanoid pathway bifurcates into the production of an enormous array of compounds based on the few intermediates of the shikimate pathway in response to cell wall breaches by pathogens. The whole metabolomic pathway is a complex network regulated by multiple gene families and it exhibits refined regulatory mechanisms at the transcriptional, post-transcriptional, and post-translational levels. The pathway genes are involved in the production of anti-microbial compounds as well as signaling molecules. The engineering in the metabolic pathway has led to a new plant defense system of which various mechanisms have been proposed including salicylic acid and antimicrobial mediated compounds. In recent years, some key players like phenylalanine ammonia lyases (PALs) from the phenylpropanoid pathway are proposed to have broad spectrum disease resistance (BSR) without yield penalties. Now we have more evidence than ever, yet little understanding about the pathway-based genes that orchestrate rapid, coordinated induction of phenylpropanoid defenses in response to microbial attack. It is not astonishing that mutants of pathway regulator genes can show conflicting results. Therefore, precise engineering of the pathway is an interesting strategy to aim at profitably tailored plants. Here, this review portrays the current progress and challenges for phenylpropanoid pathway-based resistance from the current prospective to provide a deeper understanding.
Increased temperatures caused by global warming threaten agricultural production, as warmer conditions can inhibit plant growth and development or even destroy crops in extreme circumstances. Extensive research over the past several decades has revealed that chloroplasts, the photosynthetic organelles of plants, are highly sensitive to heat stress, which affects a variety of photosynthetic processes including chlorophyll biosynthesis, photochemical reactions, electron transport, and CO2 assimilation. Important mechanisms by which plant cells respond to heat stress to protect these photosynthetic organelles have been identified and analyzed. More recent studies have made it clear that chloroplasts play an important role in inducing the expression of nuclear heat-response genes during the heat stress response. In this review, we summarize these important advances in plant-based research and discuss how the sensitivity, responses, and signaling roles of chloroplasts contribute to plant heat sensitivity and tolerance.
The influence of stress factors on the plant can, on the one hand, lead to worse functioning of the plant and loss of its crop, but on the other, it can have a positive effect on the metabolism of compounds with documented biological activity. In this study, the effect of light and drought intensity on photosynthetic activity and physiological status of two barley varieties, as well as the antimicrobial, antioxidant properties and profile of polyphenolic compounds of green barley were analysed. It was shown that under the conditions of water shortage, the KWS Olof variety showed a smaller decrease in CO2 assimilation and transpiration and higher values of these parameters at both light intensities. Only in the KWS Olof variety increased stress as a result of increased light intensity. It has also been shown that both the intensity of radiation and drought-related stress have a significant impact on the profile of polyphenolic compounds from green barley, without a simple relationship between the impact of stress factors on the content of polyphenols. Changes in the profile of polyphenolic compounds augmented the antioxidant and antimicrobial activity of the material. This, in turn, proposes the possibility of reducing the applied doses of herbal material thanks to a greater content of active substances in extracts obtained from the plants used to produce medicinal preparations.
Secondary metabolites (SMs) of medicinal plants are the material basis of their clinically curative effects. They are also important indicators for evaluating the quality of medicinal materials. However, the synthesis and accumulation of SMs are very complex, which are affected by many factors including internal developmental genetic circuits (regulated gene, enzyme) and by external environment factors (light, temperature, water, salinity, etc.). Currently, lots of literatures focused on the effect of environmental factors on the synthesis and accumulation of SMs of medicinal plants, the effect of the developmental growth and genetic factors on the synthesis and accumulation of SMs still lack systematic classification and summary. Here, we have given the review base on our previous works on the morphological development of medicinal plants and their secondary metabolites, and systematically outlined the literature reports how different environmental factors affected the synthesis and accumulation of SMs. The results of our reviews can know how developmental and environmental factors qualitatively and quantitatively influence SMs of medicinal plants and how these can be integrated as tools to quality control, as well as on the improvement of clinical curative effects by altering their genomes, and/or growth conditions.
Global warming contributes to higher temperatures and reduces rainfall for most areas worldwide. The concurrent incidence of extreme temperature and water shortage lead to temperature stress damage in plants. Seeking to imitate a more natural field situation and to figure out responses of specific stresses with regard to their combination, we investigated physiological, biochemical, and metabolomic variations following drought and heat stress imposition (alone and combined) and recovery, using Mentha piperita and Catharanthus roseus plants. Plants were exposed to drought and/or heat stress (35 °C) for seven and fourteen days. Plant height and weight (both fresh and dry weight) were significantly decreased by stress, and the effects more pronounced with a combined heat and drought treatment. Drought and/or heat stress triggered the accumulation of osmolytes (proline, sugars, glycine betaine, and sugar alcohols including inositol and mannitol), with maximum accumulation in response to the combined stress. Total phenol, flavonoid, and saponin contents decreased in response to drought and/or heat stress at seven and fourteen days; however, levels of other secondary metabolites, including tannins, terpenoids, and alkaloids, increased under stress in both plants, with maximal accumulation under the combined heat/drought stress. Extracts from leaves of both species significantly inhibited the growth of pathogenic fungi and bacteria, as well as two human cancer cell lines. Drought and heat stress significantly reduced the antimicrobial and anticancer activities of plants. The increased accumulation of secondary metabolites observed in response to drought and/or heat stress suggests that imposition of abiotic stress may be a strategy for increasing the content of the therapeutic secondary metabolites associated with these plants.
In the present study, the medicinal aromatic plant Mentha spicata has been investigated as a source of essential oil (EO) and pharmaceuticals. The quantity and composition of EO from M. spicata cultivated in Palestine were analyzed seasonally over a three-year period. A significantly higher EO content was produced in summer and fall months (2.54–2.79%). Chemical analysis of EO revealed 31 compounds with oxygenated monoterpenes (90%) as the most abundant components followed by sesquiterpene and monoterpene hydrocarbons (6 and 3%, respectively). M spicata can be characterized as a carvone chemotype (65%). EO and carvone have shown strong inhibitory activities against the principal enzymes associated with Alzheimer’s disease (AD) and overweight diseases (cholinesterase and porcine pancreatic lipase) and also shown strong antidermatophytic activity against Microsporum canis , Trichophyton rubrum , T. mentagrophytes , and Epidermophyton floccosum . The pancreatic lipase inhibition and the synergism showed the potential activity of M. spicata EO and carvone and that their combinations with standard drugs can be useful for the treatment of obesity and overweight. The results also demonstrated that, in addition to their significant inhibitory activity against biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA), M. spicata EO and carvone had a strong inhibitory effect on metabolic activity and biomass of the preformed biofilm. The current study supports the utilization of M. spicata EO as a traditional medicine and opens perceptions to find more potent substances in the EO for the management of obesity, AD, and dermatophytosis and for combating drug-resistant bacterial infections.
As superficial structures, non-glandular trichomes, protect plant organs against multiple biotic and abiotic stresses. The protective and defensive roles of these epidermal appendages are crucial to developing organs and can be attributed to the excellent combination of suitable structural traits and chemical reinforcement in the form of phenolic compounds, primarily flavonoids. Both the formation of trichomes and the accumulation of phenolics are interrelated at the molecular level. During the early stages of development, non-glandular trichomes show strong morphological similarities to glandular ones such as the balloon-like apical cells with numerous phenolics. At later developmental stages, and during secondary wall thickening, phenolics are transferred to the cell walls of the trichomes. Due to the diffuse deposition of phenolics in the cell walls, trichomes provide protection against UV-B radiation by behaving as optical filters, screening out wavelengths that could damage sensitive tissues. Protection from strong visible radiation is also afforded by increased surface light reflectance. Moreover, the mixtures of trichome phenolics represent a superficial chemical barrier that provides protection against biotic stress factors such as herbivores and pathogens. Although the cells of some trichomes die at maturity, they can modulate their quantitative and qualitative characteristics during development, depending on the prevailing conditions of the external biotic or abiotic environment. In fact, the structure and chemical constituents of trichomes may change due to the particular light regime, herbivore damage, wounding, water stress, salinity and the presence of heavy metals. Hence, trichomes represent dynamic protective structures that may greatly affect the outcome of many plant–environment interactions.
Phenolic profiling of ten plant samples of Mentha rotundifolia (L.) Huds. collected from different bioclimatic areas of Tunisia, was for the first time carried out by using a fast ultra-high-performance liquid chromatography (UHPLC)-high resolution tandem mass spectrometry (HRMS/MS) method on a Q Exactive platform equipped with an electrospray ionization (ESI) source. An intraspecific, interpopulation variability was evidenced and a total of 17 polyphenolic metabolites were identified and quantified by using the UHPLC-HRESIMS/MS method, here validated for specificity, linearity, limit of detection, limit of quantitation, accuracy and precision. The quantitative method resulted sensitive at the nM level and reliable for rapid polyphenol quantification in vegetal matrices. The metabolomic study allowed us to identify a new compound, named salvianolic acid W, which was isolated and characterized mainly by NMR and MS analysis. A statistical correlation of the phenolic composition with antioxidant and anti-acetylcholinesterase activities was provided.
Salinity and drought are the major osmotic stress limitations that affect plant growth and crop yield in agriculture worldwide. The alternative response mediated by plants in response to salinity and drought are principally proline accumulation which regulates stress combat strategies owing to sustainable production in the realm of agricultural production even under severe stress. Symbiotic and soil associated arbuscular mycorrhizal fungi (AMF) are regarded as efficient biofertilizers in several crops under these stresses. Summarily AMF is renowned for effective scavengers of free radicals in soil thereby increasing soil parameters optimal for plant growth. AMF contribute to augment host plant tolerance to stress specifically salinity and drought. Mycorrhizal colonization positively regulates root uptake of available nutrients and enhance growth even when bestowed by water constraints which has contributory roles due to proline accumulation providing several intriguing researches on AMF symbiosis pertaining to plant productivity and yield. Mycorrhizal plants and their non-mycorrhizal counterparts show varied expression pattern regarding proline amass. Hence, the precise role of proline with respect to stress tolerance and equivocal mechanisms involved in evasion of osmotic stress has not been extensively reviewed earlier. Further molecular forecasting in this arena is still an underexploited research field. This review comprehensively addresses the observable facts pertaining to proline accumulation upon AMF association and adherence relevant to stress tolerance and host plant efficiency and efficacy.
Mentha is a genus from the family Lamiaceae, whose essential oils has long been used in various forms such as in management of plant pathogens and insect pests, in traditional medicine as well as in culinary and cosmetics. Its major chemical components such as menthol, carvone have now been successfully commercialized in the industry as antimicrobials/insecticidal agents. Current review focuses on chemical composition of essential oils of some Mentha species from different geographical regions with their insecticidal (repellent, antifeedant, and ovicidal) and antimicrobial efficacies against bacterial, fungal plant pathogens and insects of stored products. Reports of the researchers on chemical analysis of essential oils of Mentha species revealed that most of the oils being rich in pulegone, menthon, menthol, carvone, 1, 8-cineole, limonene and β-caryophyllene. Reviewed literature revealed that, essential oils from different Mentha species possess potential antimicrobial activity against plant pathogens and have insecticidal activity against stored product insects. Thus, antimicrobial and insecticidal properties of essential oils of Mentha species offer the prospect of using them as natural pesticides with a commercial value, having social acceptance due to its sustainability and being environment friendly.
Essential oils of aromatic plants as an important phytochemical class have been recognized for many years as a great source of pharmaceutical agents and food additives. There are many factors influencing the chemical composition of the essential oils including extraction techniques. In this project, the effect of extraction methods (hydrodistillation, microwave assisted hydrodistillation and solvent free microwave extraction) of Mentha longifolia L. growing in Taif, KSA on the yield and chemical composition of their essential oils were investigated. In addition, anticancer and antimicrobial activities of essential oils obtained were determined. The results showed no great difference between the oil yield obtained by the three different methods, but the methods used microwave were rapid, saving time and energy than the hydrodistillation method. The qualitative chemical compositions of the three oils for each species were similar with little quantitative differences of some compounds between the three methods. The oils consist mainly from monoterpenes and sesquiterpenes in which pulegone was the main component. All essential oils showed high antibacterial activity and moderate in vitro anticancer activity. In conclusion, this considered the first study represented the effect of microwave extraction in the chemical composition of M. longifolia essential oil growing in Taif, KSA. The authors recommended the usage of the microwave method in the extraction of mint essential oil because it is energy and time saving, in addition to environmentally friendly.
Plants have evolved the adaptive capacity to mitigate the negative effect of external adversities at chemical, molecular, cellular, and physiological levels. This capacity is conferred by triggering the coordinated action of internal regulatory factors, in which sugars play an essential role in the regulating chloroplast degradation and leaf senescence under various stresses. In this review, we summarize the recent findings on the senescent-associated changes in carbohydrate metabolism and its relation to chlorophyl degradation, oxidative damage, photosynthesis inhibition, programmed cell death (PCD), and sink-source relation as affected by abiotic stresses. The action of sugar signaling in regulating the initiation and progression of leaf senescence under abiotic stresses involves interactions with various plant hormones, reactive oxygen species (ROS) burst, and protein kinases. This discussion aims to elucidate the complex regulatory network and molecular mechanisms that underline sugar-induced leaf senescence in response to various abiotic stresses. The imperative role of sugar signaling in regulating plant stress responses potentially enables the production of crop plants with modified sugar metabolism. This, in turn, may facilitate the engineering of plants with improved stress responses, optimal life span and higher yield achievement.
Terpenoids and their derivatives, synthesised via the MEP or MVA pathways, are a diverse class of natural compounds with anticancer, antimicrobial, antiparasitic, and antiallergenic properties. Terpenoids are in high demand worldwide due to their medicinal applications and prospective benefits in numerous fields. Due to their low abundance in nature, these chemicals are limited in application. These chemicals are also meeting global demand through petroleum-based manufacture. However, rising greenhouse gas emissions and global warming make the aforementioned strategy untenable for commercial production. Metabolic pathway engineering, a promising synthetic biology technology, may efficiently modify microbial pathways to create high-value chemicals continuously and sustainably. This review emphasises MEP pathway relevance and utility for tailored terpenoids production. The types of terpenoids, their commercial uses, and engineering efforts to boost cell factory terpenoids are also explored.
Covering: 1997 to 2023The shikimate pathway is the metabolic process responsible for the biosynthesis of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. Seven metabolic steps convert phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P) into shikimate and ultimately chorismate, which serves as the branch point for dedicated aromatic amino acid biosynthesis. Bacteria, fungi, algae, and plants (yet not animals) biosynthesize chorismate and exploit its intermediates in their specialized metabolism. This review highlights the metabolic diversity derived from intermediates of the shikimate pathway along the seven steps from PEP and E4P to chorismate, as well as additional sections on compounds derived from prephenate, anthranilate and the synonymous aminoshikimate pathway. We discuss the genomic basis and biochemical support leading to shikimate-derived antibiotics, lipids, pigments, cofactors, and other metabolites across the tree of life.
Selenium (Se) beneficial effect on plants is related to an increase in nitrogen (N) assimilation and its role as an abiotic stress mitigator by reactive oxygen species (ROS) scavenging enhanced by antioxidant metabolism. This study aimed to evaluate sugarcane (Saccharum spp.) growth, photosynthetic and antioxidant responses, and sugar accumulation in response to Se supply. The experimental design was a factorial scheme 2 × 4: two sugarcane varieties (RB96 6928 and RB86 7515) and four Se application rates (0; 5; 10 and 20 μmol L-1) applied as sodium selenate in the nutrient solution. Leaf Se concentration increased under Se application in both varieties. The enzymes SOD (EC 1.15.1.1) and APX (EC 1.11.1.11) showed increase activities under Se application on variety RB96 6928. Nitrate reductase activity increased in both varieties resulting in the conversion of nitrate into higher total amino acids concentration indicating an enhanced N assimilation. This led to an increased concentration of chlorophylls and carotenoids, increased CO2 assimilation rate, stomatal conductance, and internal CO2 concentration. Selenium provided higher starch accumulation and sugar profiles in leaves boosting plant growth. This study shows valuable information regarding the role of Se on growth, photosynthetic process, and sugar accumulation in sugarcane leaves, which could be used for further field experiments. The application rate of 10 μmol Se L-1 was the most adequate for both varieties studied considering the sugar concentration and plant growth.
Terpenoids are a large class of plant-derived compounds, that constitute the main components of essential oils and are widely used as natural flavors and fragrances. The biosynthesis approach presents a promising alternative route in terpenoid production compared to plant extraction or chemical synthesis. In the past decade, the production of terpenoids using biotechnology has attracted broad attention from both academia and the industry. With the growing market of flavor and fragrance, the production of terpenoids directed by synthetic biology shows great potential in promoting future market prospects. Here, we reviewed the latest advances in terpenoid biosynthesis. The engineering strategies for biosynthetic terpenoids were systematically summarized from the enzyme, metabolic, and cellular dimensions. Additionally, we analyzed the key challenges from laboratory production to scalable production, such as key enzyme improvement, terpenoid toxicity, and volatility loss. To provide comprehensive technical guidance, we collected milestone examples of biosynthetic mono- and sesquiterpenoids, compared the current application status of chemical synthesis and biosynthesis in terpenoid production, and discussed the cost drivers based on the data of techno-economic assessment. It is expected to provide critical insights into developing translational research of terpenoid biomanufacturing.
Spearmint belongs to the genus Mentha in the family Labiatae (Lamiaceae), which is cultivated worldwide for its remarkable aroma and commercial value. The aromatic molecules of spearmint essential oil, including carvone, carveol, dihydrocarvone, dihydrocarveol and dihydrocarvyl acetate, have been widely used in the flavors and fragrances industry. Besides their traditional use, these aromatic molecules have attracted great interest in other application fields (e.g., medicine, agriculture, food, and beverages) especially due to their antimicrobial, antioxidant, insecticidal, antitumor, anti-inflammatory and antidiabetic activities. This review presents the sources, properties, synthesis and application of spearmint aromatic molecules. Furthermore, this review focuses on the biological properties so far described for these compounds, their therapeutic effect on some diseases, and future directions of research. This review will, therefore, contribute to the rational and economic exploration of spearmint aromatic molecules as natural and safe alternative therapeutics.
Benzenoid and terpenoid volatiles are the major compounds contributing to the unique floral scent of Jasminum auriculatum. Biosynthesis and emission of specialized scent metabolites showed maturation stage specific pattern; maximum scent emission was observed when flowers start unfurling and become fully opened under in situ condition. The activities of volatile biosynthesizing enzymes and expressions of several scent-related genes correlated well with the fragrance emission patterns. We also assessed the impact of varying air temperatures (20 °C, 25 °C, 30 °C and 35 °C) on the metabolism as well as vaporization of scent volatiles. The contents of both emitted and endogenous volatiles were higher at either 25 °C or 30 °C and showed relatively lower amounts at both border-range temperatures (20 °C and 35 °C). Further, the activities of key pathway enzymes and expressions of several scent-related genes under varying temperatures exhibited similar trends with the scent emission patterns. Analysis of non-volatile metabolites from flowers grown under different air temperatures suggests a perturbation occurring in the primary metabolism and immediate precursors of scent compounds. The knowledge base created through these studies shall be helpful in improving the yield of floral scent production from such horticulturally important plants in controlled cultivation systems.
This collaborative study was conducted to determine the total monomeric anthocyanin concentration by the pH differential method, which is a rapid and simple spectrophotometric method based on the anthocyanin structural transformation that occurs with a change in pH (colored at pH 1.0 and colorless at pH 4.5). Eleven collaborators representing commercial laboratories, academic institutions, and government laboratories participated. Seven Youden pair materials representing fruit juices, beverages, natural colorants, and wines were tested. The repeatability relative standard deviation (RSDr) varied from 1.06 to 4.16%. The reproducibility relative standard deviation (RSDR) ranged from 2.69 to 10.12%. The HorRat values were ≤1.33 for all materials. The Study Director recommends that the method be adopted Official First Action.
In plants, cell wall bound phenolics change in response to stress. The aim of the study was to investigate the effect of NaCl induced stress on wall bound phenolics in four rice varieties, of which two (Bhutnath, Nonabokra) were salt tolerant and two (MTU 7029, Sujala) were salt sensitive. After germination, seedlings were grown in hydroponic solution and subjected to salinity stress (25mM, 50mM, 100mM and 150mM NaCl) on day 12. Wall bound phenolic compounds were determined by GC-MS based metabolite analysis. Total seven wall bound phenols were identified from the leaf tissues and eight from the root tissues. Ferulic acid and 4-hydroxycinnamic acid were found in all the four varieties. After NaCl treatment, these two wall bound phenols increased in tolerant varieties only. Significant inverse correlation between leaf length and leaf fresh weight with wall bound ferulic acid and 4-hydroxycinnamic acid in Nonabokra suggests the positive role of these wall bound phenolics in salt tolerance.