Abiotic Stress-Induced Secondary Metabolites Regulating Plant Metabolism

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Physiology and Metabolism".

Deadline for manuscript submissions: 20 October 2024 | Viewed by 7746

Special Issue Editor


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Guest Editor
College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
Interests: phytochemicals accumulation; sprouts producing; seeds germination; gamma-aminobutyric acid metabolism and its signal function; phenolics accumulation; food chemistry; metabolomics
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Special Issue Information

Dear Colleagues,

When plants are exposed to adverse conditions such as mechanical damage, drought, waterlogging, salinity, ultraviolet radiation, heavy metal pollution, etc., its body produces a series of complex biochemical reactions to activate its own defense system in response to environmental stress. At the same time, the plant is often accompanied by the synthesis and accumulation of secondary metabolites with strong antioxidant capacities, such as flavonoids, phenolic acids, and gamma-aminobutyric acid. Besides, the secondary metabolite presents in plants with one or more aromatic rings containing one or more hydroxyl groups, which have a wide spectrum of biological activities, including antioxidant, antibiosis, etc. Therefore, the synthesis and accumulation of plant secondary metabolites have received extensive attention. In higher plants, the secondary metabolites are generally converted from carbohydrates. The plant organism realizes the synthesis and metabolism of specific compounds by regulating the genes, protein expression levels and signaling of key enzymes in its anabolic pathway. At the same time, these secondary metabolites have the role of regulating plant growth and metabolism. This Special Issue of Plants will highlight the function, synthesis, and diversity of plant secondary metabolites in plants and their accumulation under abiotic stress.

Dr. Runqiang Yang
Guest Editor

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Keywords

  • abiotic stress
  • plants
  • sprouts
  • germination
  • signal transition
  • phenolics accumulation
  • gamma-aminobutyric acid
  • metabolism

Published Papers (8 papers)

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Research

16 pages, 3172 KiB  
Article
Unraveling the Role of AtSRT2 in Energy Metabolism, Stress Responses, and Gene Expression during Osmotic Stress in Arabidopsis thaliana
by Alberto Obrecht and Manuel Paneque
Plants 2024, 13(5), 711; https://doi.org/10.3390/plants13050711 - 02 Mar 2024
Viewed by 687
Abstract
Sirtuins participate in chromatin remodeling and gene expression regulation during stress responses. They are the only deacetylases that couple the cellular NAD+-dependent energy metabolism with transcriptional regulation. They catalyze the production of nicotinamide, inhibiting sirtuin 2 (SIR2) activity in vivo. The [...] Read more.
Sirtuins participate in chromatin remodeling and gene expression regulation during stress responses. They are the only deacetylases that couple the cellular NAD+-dependent energy metabolism with transcriptional regulation. They catalyze the production of nicotinamide, inhibiting sirtuin 2 (SIR2) activity in vivo. The SIR2 homolog, AtSRT2, deacetylates non-histone proteins associated with mitochondrial energy metabolism. To date, AtSRT2 mechanisms during stress responses in Arabidopsis thaliana remain unclear. The transduction of mitochondrial metabolic signals links the energy status to transcriptional regulation, growth, and stress responses. These signals induce changes by regulating nuclear gene expression. The present study aimed to determine the role of SRT2 and its product nicotinamide in the development of A. thaliana and the expression of osmotic stress-response genes. Leaf development was greater in srt2+ plants than in the wild type, indicating that SET2 plays a role in energy metabolism. Treatment with polyethylene glycol activated and inhibited gene expression in srt2- and srt2+ lines, respectively. Therefore, we concluded that SRT2-stimulated plant growth and repressed signaling are associated with osmotic stress. Full article
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14 pages, 3422 KiB  
Article
The Cooperation Regulation of Antioxidative System and Hormone Contents on Physiological Responses of Wedelia trilobata and Wedelia chinensis under Simulated Drought Environment
by Ping Huang, Zhiwei Xu, Weijie He, Hong Yang, Bin Li, Wendian Ding, Yuze Lei, Adeel Abbas, Rashida Hameed, Congyan Wang, Jianfan Sun and Daolin Du
Plants 2024, 13(4), 472; https://doi.org/10.3390/plants13040472 - 07 Feb 2024
Viewed by 741
Abstract
Drought-induced metabolic dysregulation significantly enhances the production of reactive oxygen species (ROS), which, in turn, exerts a substantial influence on the oxidation–reduction regulatory status of cells. These ROS, under conditions of drought stress, become highly reactive entities capable of targeting various plant organelles, [...] Read more.
Drought-induced metabolic dysregulation significantly enhances the production of reactive oxygen species (ROS), which, in turn, exerts a substantial influence on the oxidation–reduction regulatory status of cells. These ROS, under conditions of drought stress, become highly reactive entities capable of targeting various plant organelles, metabolites, and molecules. Consequently, disruption affects a wide array of metabolic pathways and eventually leads to the demise of the cells. Given this understanding, this study aimed to investigate the effects of different drought stress levels on the growth and development of the invasive weed Wedelia trilobata and its co-responding native counterpart Wedelia chinensis. Both plants evolved their defense mechanisms to increase their antioxidants and hormone contents to detoxify ROS to avoid oxidative damage. Still, the chlorophyll content fluctuated and increased in a polyethylene-glycol-simulated drought. The proline content also rose in the plants, but W. chinensis showed a significant negative correlation between proline and malondialdehyde in different plant parts. Thus, W. trilobata and W. chinensis exhibited diverse or unlike endogenous hormone regulation patterns under drought conditions. Meanwhile, W. trilobata and W. chinensis pointedly increased the content of indole acetic acid and gibberellic acid in a different drought stress environment. A positive correlation was found between endogenous hormones in other plant parts, including in the roots and leaves. Both simulated and natural drought conditions exerted a significant influence on both plant species, with W. trilobata displaying superior adaptation characterized by enhanced growth, bolstered antioxidant defense mechanisms, and heightened hormonal activities. Full article
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15 pages, 1932 KiB  
Article
Effect of UV-A Irradiation on Bioactive Compounds Accumulation and Hypoglycemia-Related Enzymes Activities of Broccoli and Radish Sprouts
by Gongheng Che, Mingmei Chen, Xiaodan Li, Junxia Xiao, Liang Liu and Liping Guo
Plants 2024, 13(3), 450; https://doi.org/10.3390/plants13030450 - 03 Feb 2024
Viewed by 759
Abstract
In the present study, different intensities of UV-A were applied to compare their effects on growth, bioactive compounds and hypoglycemia-related enzyme activities in broccoli and radish sprouts. The growth of sprouts was decreased after UV-A irradiation. A total of 12 W of UV-A [...] Read more.
In the present study, different intensities of UV-A were applied to compare their effects on growth, bioactive compounds and hypoglycemia-related enzyme activities in broccoli and radish sprouts. The growth of sprouts was decreased after UV-A irradiation. A total of 12 W of UV-A irradiation resulted in the highest content of anthocyanin, chlorophyll, polyphenol and ascorbic acid in broccoli and radish sprouts. The highest soluble sugar content was recorded in sprouts under 8 W of UV-A irradiation, while no significant difference was obtained in soluble protein content among different UV-A intensities. Furthermore, 12 W of UV-A irradiation induced the highest glucosinolate accumulation, especially glucoraphanin and glucoraphenin in broccoli and radish sprouts, respectively; thus, it enhanced sulforaphane and sulforaphene formation. The α-amylase, α-glucosidase and pancrelipase inhibitory rates of two kinds of sprouts were enhanced significantly after UV-A irradiation, indicating UV-A-irradiation-treated broccoli and radish sprouts have new prospects as hypoglycemic functional foods. Full article
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24 pages, 10962 KiB  
Article
Integration of Physiological, Transcriptomic, and Metabolomic Analyses Reveal Molecular Mechanisms of Salt Stress in Maclura tricuspidata
by Dezong Sui, Baosong Wang, Yousry A. El-Kassaby and Lei Wang
Plants 2024, 13(3), 397; https://doi.org/10.3390/plants13030397 - 29 Jan 2024
Viewed by 765
Abstract
Salt stress is a universal abiotic stress that severely affects plant growth and development. Understanding the mechanisms of Maclura tricuspidate’s adaptation to salt stress is crucial for developing salt-tolerant plant varieties. This article discusses the integration of physiology, transcriptome, and metabolome to [...] Read more.
Salt stress is a universal abiotic stress that severely affects plant growth and development. Understanding the mechanisms of Maclura tricuspidate’s adaptation to salt stress is crucial for developing salt-tolerant plant varieties. This article discusses the integration of physiology, transcriptome, and metabolome to investigate the mechanism of salt adaptation in M. tricuspidata under salt stress conditions. Overall, the antioxidant enzyme system (SOD and POD) of M. tricuspidata exhibited higher activities compared with the control, while the content of soluble sugar and concentrations of chlorophyll a and b were maintained during salt stress. KEGG analysis revealed that deferentially expressed genes were primarily involved in plant hormone signal transduction, phenylpropanoid and flavonoid biosynthesis, alkaloids, and MAPK signaling pathways. Differential metabolites were enriched in amino acid metabolism, the biosynthesis of plant hormones, butanoate, and 2-oxocarboxylic acid metabolism. Interestingly, glycine, serine, and threonine metabolism were found to be important both in the metabolome and transcriptome–metabolome correlation analyses, suggesting their essential role in enhancing the salt tolerance of M. tricuspidata. Collectively, our study not only revealed the molecular mechanism of salt tolerance in M. tricuspidata, but also provided a new perspective for future salt-tolerant breeding and improvement in salt land for this species. Full article
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20 pages, 9157 KiB  
Article
Metabolic Mechanisms Underlying Heat and Drought Tolerance in Lentil Accessions: Implications for Stress Tolerance Breeding
by Noureddine El Haddad, Youness En-nahli, Hasnae Choukri, Khawla Aloui, Rachid Mentag, Adil El-Baouchi, Kamal Hejjaoui, Karthika Rajendran, Abdelaziz Smouni, Fouad Maalouf and Shiv Kumar
Plants 2023, 12(23), 3962; https://doi.org/10.3390/plants12233962 - 24 Nov 2023
Cited by 2 | Viewed by 1101
Abstract
Climate change has significantly exacerbated the effects of abiotic stresses, particularly high temperatures and drought stresses. This study aims to uncover the mechanisms underlying heat and drought tolerance in lentil accessions. To achieve this objective, twelve accessions were subjected to high-temperature stress (32/20 [...] Read more.
Climate change has significantly exacerbated the effects of abiotic stresses, particularly high temperatures and drought stresses. This study aims to uncover the mechanisms underlying heat and drought tolerance in lentil accessions. To achieve this objective, twelve accessions were subjected to high-temperature stress (32/20 °C), while seven accessions underwent assessment under drought stress conditions (50% of field capacity) during the reproductive stage. Our findings revealed a significant increase in catalase activity across all accessions under both stress conditions, with ILL7814 and ILL7835 recording the highest accumulations of 10.18 and 9.33 under drought stress, respectively, and 14 µmol H2O2 mg protein−1 min−1 under high temperature. Similarly, ascorbate peroxidase significantly increased in all tolerant accessions due to high temperatures, with ILL6359, ILL7835, and ILL8029 accumulating the highest values with up 50 µmol ascorbate mg protein−1 min−1. In contrast, no significant increase was obtained for all accessions subjected to water stress, although the drought-tolerant accessions accumulated more APX activity (16.59 t to 25.08 µmol ascorbate mg protein−1 min−1) than the sensitive accessions. The accessions ILL6075, ILL7814, and ILL8029 significantly had the highest superoxide dismutase activity under high temperature, while ILL6363, ILL7814, and ILL7835 accumulated the highest values under drought stress, each with 22 to 25 units mg protein−1. Under both stress conditions, ILL7814 and ILL7835 recorded the highest contents in proline (38 to 45 µmol proline/g FW), total flavonoids (0.22 to 0.77 mg QE g−1 FW), total phenolics (7.50 to 8.79 mg GAE g−1 FW), total tannins (5.07 to 20 µg CE g−1 FW), and total antioxidant activity (60 to 70%). Further, ILL7814 and ILL6338 significantly recorded the highest total soluble sugar content under high temperature (71.57 and 74.24 mg g−1, respectively), while ILL7835 achieved the maximum concentration (125 mg g−1) under drought stress. The accessions ILL8029, ILL6104, and ILL7814 had the highest values of reducing sugar under high temperature with 0.62 to 0.79 mg g−1, whereas ILL6075, ILL6363, and ILL6362 accumulated the highest levels of this component under drought stress with 0.54 to 0.66 mg g−1. Overall, our findings contribute to a deeper understanding of the metabolomic responses of lentil to drought and heat stresses, serving as a valuable reference for lentil stress tolerance breeding. Full article
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12 pages, 2336 KiB  
Article
Investigation into the Relationship between Spermidine Degradation and Phenolic Compounds Biosynthesis in Barley Seedlings under Ultraviolet B Stress
by Chong Xie, Yahui Zhu, Chaoqun Leng, Qiaoe Wang, Pei Wang and Runqiang Yang
Plants 2023, 12(20), 3533; https://doi.org/10.3390/plants12203533 - 11 Oct 2023
Viewed by 808
Abstract
Barley germination under ultraviolet B (UV-B) illumination stress induces effective accumulation of phenolic compounds in the barley. Spermidine can enhance the biosynthesis of phenolic compounds and alleviate the oxidative damage caused by UV-B. To better understand the function of spermidine, inhibitors of enzymes [...] Read more.
Barley germination under ultraviolet B (UV-B) illumination stress induces effective accumulation of phenolic compounds in the barley. Spermidine can enhance the biosynthesis of phenolic compounds and alleviate the oxidative damage caused by UV-B. To better understand the function of spermidine, inhibitors of enzymes that are involved in the degradation of spermidine and the synthesis of gamma-aminobutyric acid (GABA), the product of spermidine degradation, were applied to barley germinated under UV-B treatment. The results showed a more severe oxidative damage, and a decrease in phenolic acid contents were observed when spermidine degradation was inhibited. However, GABA application did attenuate an increase in electrolyte permeability and MDA content caused by UV-B induced oxidative damage and improved the respiration rate. Meanwhile, GABA application can elevate the accumulation of phenolic compounds by ca. 20%, by elevating the activities of some key enzymes. Furthermore, the application of GABA, together with the inhibitor of spermidine degradation, can alleviate its suppression of the synthesis of phenolic acids, and resistance to UV-B stress. In conclusion, spermidine alleviated oxidative damage and enhanced the accumulation of phenolic compounds using its degradation product. Full article
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19 pages, 2885 KiB  
Article
Comparative Physiological and Transcriptome Analyses Reveal Mechanisms of Salicylic-Acid-Reduced Postharvest Ripening in ‘Hosui’ Pears (Pyrus pyrifolia Nakai)
by Jing Zhang, Mengmeng Wen, Rong Dai, Xiao Liu and Chunlei Wang
Plants 2023, 12(19), 3429; https://doi.org/10.3390/plants12193429 - 28 Sep 2023
Viewed by 920
Abstract
Postharvest ripening of sand pear fruit leads to quality deterioration, including changes in texture, flavor, and fruit color. Salicylic acid (SA), an important defense-related hormone, delays fruit ripening and maintains fruit quality, but the underling mechanism remains unclear. Herein, we evaluated the efficacy [...] Read more.
Postharvest ripening of sand pear fruit leads to quality deterioration, including changes in texture, flavor, and fruit color. Salicylic acid (SA), an important defense-related hormone, delays fruit ripening and maintains fruit quality, but the underling mechanism remains unclear. Herein, we evaluated the efficacy of SA in delaying the ripening process of Pyrus pyrifolia cv. ’Hosui’ pear fruit, as evidenced by the reduction in fruit weight loss, inhibition of firmness loss, cell wall degradation and soluble sugars, and retention of total phenols. Based on comparative transcriptomic data, a total of 3837 and 1387 differentially expressed genes (DEGs) were identified during room-temperature storage of control fruit and between SA-treated and control fruit, respectively. Further KEGG analysis revealed that the DEGs were mainly implicated in plant hormone signal transduction, starch and sugar metabolism, and cell wall modification. Moreover, exogenous SA treatment also altered the expression of many transcription factor (TF) families, including those in the ethylene-responsive factor (ERF), NAM, ATAF, CUC (NAC), basic helix-loop-helix (bHLH), basic leucine zipper (bZIP), and v-myb avian myeloblastosis viral oncogene homolog (MYB) families. Together, the results offer important insights into the role of SA-responsive genes in controlling fruit ripening in sand pears. Full article
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15 pages, 2366 KiB  
Article
GABA Application Enhances Drought Stress Tolerance in Wheat Seedlings (Triticum aestivum L.)
by Qiuyan Zhao, Yan Ma, Xianqing Huang, Lianjun Song, Ning Li, Mingwu Qiao, Tiange Li, Dan Hai and Yongxia Cheng
Plants 2023, 12(13), 2495; https://doi.org/10.3390/plants12132495 - 29 Jun 2023
Cited by 6 | Viewed by 1277
Abstract
In this study, the effects of γ-aminobutyric acid (GABA) on physio-biochemical metabolism, phenolic acid accumulation, and antioxidant system enhancement in germinated wheat under drought stress was investigated. The results showed that exogenous GABA reduced the oxidative damage in wheat seedlings caused by drought [...] Read more.
In this study, the effects of γ-aminobutyric acid (GABA) on physio-biochemical metabolism, phenolic acid accumulation, and antioxidant system enhancement in germinated wheat under drought stress was investigated. The results showed that exogenous GABA reduced the oxidative damage in wheat seedlings caused by drought stress and enhanced the content of phenolics, with 1.0 mM being the most effective concentration. Six phenolic acids were detected in bound form, including p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid, and sinapic acid. However, only syringic acid and p-coumaric acid were found in free form. A total of 1.0 mM of GABA enhanced the content of total phenolic acids by 28% and 22%, respectively, compared with that of drought stress, on day four and day six of germination. The activities of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate coenzyme A ligase (4CL) were activated by drought stress plus GABA treatment. Antioxidant enzyme activities were also induced. These results indicate that GABA treatment may be an effective way to relieve drought stress as it activates the antioxidant system of plants by inducing the accumulation of phenolics and the increase in antioxidant enzyme activity. Full article
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