Exogenous Proline Improves Salt Tolerance of Alfalfa through Modulation of Antioxidant Capacity, Ion Homeostasis, and Proline Metabolism

Guo, Shuaiqi; Ma, Xuxia; Cai, Wenbin; Wang, Yuan; Gao, Xueqin; Fu, Bingzhe; Li, Shuxia

doi:10.3390/plants11212994

Cited by 17 publications

(8 citation statements)

References 60 publications

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“…can contribute their own electrons to convert oxygen radicals into stable substances ( Deng et al., 2022 ). Exogenous proline and 4-aminobutyric acid reduce the oxidative damage of barley seedlings under aluminium and proton stress by enhancing the activities of the antioxidant enzymes SOD, POD and CAT ( Song et al., 2010 ; Guo et al., 2022 ). Acidic amino acids, including glutamic acid and aspartic acid, can act as proton donors to pair with lone pair electrons and thus exert antioxidant effects ( Zhang et al., 2016 ; Li et al., 2021 ) or enhance the antioxidant capacity by increasing antioxidant enzyme activity ( Liu and Yang, 2015 ; Fardus et al., 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Exogenous leucine alleviates heat stress and improves saponin synthesis in Panax notoginseng by improving antioxidant capacity and maintaining metabolic homeostasis

Liu

Yang

et al. 2023

Front. Plant Sci.

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Panax notoginseng saponins (PNSs) are used as industrial raw materials to produce many drugs to treat cardio-cerebrovascular diseases. However, it is a heat-sensitive plant, and its large-scale artificial cultivation is impeded by high temperature stress, leading to decreases in productivity and PNSs yield. Here, we examined exogenous foliar leucine to alleviate heat stress and explored the underlying mechanism using metabolomics. The results indicated that 3 and 5 mM exogenous foliar leucine significantly alleviated heat stress in one-year- and two-year-old P. notoginseng in pots and field trials. Exogenous foliar leucine enhanced the antioxidant capacity by increasing the activities of antioxidant enzymes (POD, SOD) and the contents of antioxidant metabolites (amino acids). Moreover, exogenous foliar leucine enhanced carbohydrate metabolism, including sugars (sucrose, maltose) and TCA cycle metabolites (citric acid, aconitic acid, succinic acid and fumaric acid), in P. notoginseng leaves, stems, and fibrous roots to improve the energy supply of plants and further alleviate heat stress. Field experiments further verified that exogenous foliar leucine increased the productivity and PNSs accumulation in P. notoginseng. These results suggest that leucine application is beneficial for improving the growth and quality of P. notoginseng under heat stress. It is therefore possible to develop plant growth regulators based on leucine to improve the heat resistance of P. notoginseng and other crops.

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Section: Discussionmentioning

confidence: 99%

Exogenous leucine alleviates heat stress and improves saponin synthesis in Panax notoginseng by improving antioxidant capacity and maintaining metabolic homeostasis

Liu

Yang

et al. 2023

Front. Plant Sci.

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“…In this study, H 2 O 2 concentration was revealed to be inhibited in a dose-dependent manner among the NaCl concentrations. CAT, SOD, POD, and ascorbate peroxidase (APX) are the main antioxidant enzymes that scavenge excess ROS in plants [ 56 ]. SOD is regarded as the key enzyme that facilitates the catalyzing of O 2 •− to H 2 O 2 whereas CAT rapidly decomposes H 2 O 2 , producing H 2 O and O 2 [ 47 , 54 ].…”

Section: Discussionmentioning

confidence: 99%

“…In L. ruthenicum , P5CS activity and expression of LrP5CS1 , -2 and -3 genes were promoted under high NaCl treatments. Other scholars have reported that in hybrid glycophyte Medicago sativa , increased in P5CS activity and P5CS expression after NaCl treatment revealed an involvement of P5CS in proline biosynthesis [ 56 ]. Also, in halophyte K. virginica , it is reported that overexpression of KvP5CS1 resulted in proline hyperaccumulation [ 50 ], and the overexpression of VaP5CS and LrP5CS in some glycophyte species such as Vigna aconitifolia and Lilium regale revealed proline accumulation and consequently enhanced stress tolerance [ 50 , 61 , 62 , 63 ].…”

Section: Discussionmentioning

confidence: 99%

Proline Metabolism Process and Antioxidant Potential of Lycium ruthenicum Murr. in Response to NaCl Treatments

Tiika,

Duan,

Yang

et al. 2023

IJMS

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Salinity influences the level of antioxidants and proline content, which are both involved in the regulation of stress responses in plants. To examine the interplay between the antioxidant system and proline metabolism in plant stress acclimation, explants of Lycium ruthenicum were subjected to NaCl treatments, and the growth characteristics, antioxidant enzyme activities, proline accumulation, and metabolic enzyme content were analyzed. The results revealed that NaCl concentrations between 50 to 150 mM have a positive effect on the growth of L. ruthenicum explants. Increasing NaCl concentrations elevated the activities of superoxide dismutase (SOD) and catalase (CAT), while hydrogen peroxide (H2O2) content was inhibited, suggesting that the elevated antioxidants play a central protective role in superoxide anion (O2•−) and H2O2 scavenging processes in response to NaCl treatments. Also, high proline levels also protect antioxidant enzyme machinery, thus protecting the plants from oxidative damage and enhancing osmotic adjustment. Increasing levels of pyrroline-5-carboxylate synthetase (P5CS), pyrroline-5-carboxylate reductase (P5CR), and ornithine-δ-aminotransferase (δ-OAT) were observed, resulting in elevated level of proline. In addition, the expression levels of LrP5CS1, -2, -3, LrOAT-1, and -2 were promoted in NaCl treatments. According to the combined analysis of metabolic enzyme activities and their relative expression, it is confirmed that the glutamate (Glu) pathway is activated in L. ruthenicum faced with different levels of NaCl concentrations. However, Glu supplied by δ-OAT is fed back into the main pathway for proline metabolism.

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“…In this context, studying the molecular regulation mechanism of salt tolerance in alfalfa can accelerate the development of new salt-tolerant varieties, effectively addressing the limitations imposed by soil salinization on alfalfa cultivation areas. Consequently, this will enhance the scale and level of the forage industry and play a vital role in promoting the development of circular ecological agriculture centered around forage and animal husbandry [12][13][14]. Existing research has elucidated the mechanisms underlying salt-alkali tolerance in alfalfa, focusing on areas such as seed germination, plant growth and development, physiological and biochemical reactions, and molecular biology [15].…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic Analysis of Melatonin-Mediated Salt Stress Response in Germinating Alfalfa

Liu,

Ren,

Zhu

et al. 2024

Agriculture

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Salt stress poses a significant threat to crop yields worldwide. Melatonin (MT), an endogenous hormone synthesized in plants, has emerged as a crucial player in plant responses to various abiotic stresses, including drought, salinity, heat, and cold. However, the precise molecular mechanisms underlying MT-mediated abiotic stress responses remain incompletely understood. To elucidate the key genes and pathways involved in MT-mediated alleviation of salt stress, we conducted physiological, biochemical, and transcriptomic analyses on alfalfa seedlings. Our results demonstrated that alfalfa seedlings treated with melatonin exhibited higher germination rates, longer bud lengths, and greater fresh weights compared to those subjected to salt stress alone. Furthermore, the levels of malondialdehyde (MDA) and superoxide anion (O2−) were reduced, while the activities and contents of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and glutathione (GSH) increased in response to melatonin treatment. Transcriptome analysis revealed 2181 differentially expressed genes (DEGs) in the salt-treated group, with 780 upregulated and 1401 downregulated genes. In contrast, the MT-treated group exhibited 4422 DEGs, including 1438 upregulated and 2984 downregulated genes. Functional annotation and pathway enrichment analysis indicated that DEGs were primarily involved in the biosynthesis of flavonoids, isoflavones, plant hormones, glutathione (GSH), soluble sugars, and other substances, as well as in ABC transporter and MAPK signaling pathways. Notably, the MT-treated group showed greater enrichment of DEGs in these pathways, suggesting that MT mitigates salt stress by modulating the expression of genes related to phytohormones and antioxidant capacity. Overall, our findings provide valuable insights into the molecular mechanisms underlying MT-mediated salt tolerance in alfalfa, with important implications for breeding salt-tolerant alfalfa and other crops.

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Exogenous Proline Improves Salt Tolerance of Alfalfa through Modulation of Antioxidant Capacity, Ion Homeostasis, and Proline Metabolism

Cited by 17 publications

References 60 publications

Exogenous leucine alleviates heat stress and improves saponin synthesis in Panax notoginseng by improving antioxidant capacity and maintaining metabolic homeostasis

Exogenous leucine alleviates heat stress and improves saponin synthesis in Panax notoginseng by improving antioxidant capacity and maintaining metabolic homeostasis

Proline Metabolism Process and Antioxidant Potential of Lycium ruthenicum Murr. in Response to NaCl Treatments

Transcriptomic Analysis of Melatonin-Mediated Salt Stress Response in Germinating Alfalfa

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