Priming Effect of Exogenous ABA on Heat Stress Tolerance in Rice Seedlings is Associated with the Upregulation of Antioxidative Defense Capability and Heat Shock-Related Genes

Abstract Heat stress is a major restrictive factor that suppresses rice production. In this study, we investigated the potential priming effect of exogenous abscisic acid (ABA) on heat tolerance in rice seedlings. Seedlings were pretreated with 10 μM ABA by root drenching for 24 h and then subjected to heat stress conditions of 40 °C day/35 °C night. ABA pretreatment significantly decreased leaf withering by 2.5– 28.5% and chlorophyll loss by 12.8–35.1% induced by heat stress in rice seedlings. ABA application also mitigated cell injury, as shown by lower malondialdehyde (MDA) content, membrane injury and expression of cell death-related genes OsKOD1 , OsCP1 and OsNAC4 , while expression of OsBI1 , a cell death-suppressor gene, was upregulated by ABA pretreatment. Moreover, ABA pretreatment improved antioxidant defense capacity, as shown by an obvious upregulation of ROS-scavenging genes and a decrease in ROS content (O 2 – and H 2 O 2 ) and downregulation of the OsRbohs gene. The application of fluridone, an ABA biosynthesis inhibitor, increased membrane injury and the accumulation of ROS under heat stress. Exogenous potent antioxidants (proanthocyanidins, PC) significantly alleviated leaf withering by decreasing ROS overaccumulation and membrane injury induced by heat stress. In addition, ABA pretreatment significantly superinduced the expression of ABA-responsive genes SalT and OsWsi18 , the ABA biosynthesis genes OsNCED3 and OsNCED4 , and the heat shock-related genes OsHSP23.7 , OsHSP17.7 , OsHSF7 and OsHsfA2a . Taken together, these results suggest that exogenous ABA has a potential priming effect for enhancing heat stress tolerance of rice seedlings mainly by improving antioxidant defense capacity and heat shock-related genes.

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Role of Heat Shock Proteins (HSPs) and Heat Stress Tolerance in Crop Plants

Sustainable Agriculture in the Era of Climate Change ◽

10.1007/978-3-030-45669-6_9 ◽

2020 ◽

pp. 211-234

Author(s):

Zeba Khan ◽

Durre Shahwar

Keyword(s):

Heat Stress ◽

Heat Shock ◽

Heat Shock Proteins ◽

Stress Tolerance ◽

Crop Plants ◽

Heat Stress Tolerance ◽

Shock Proteins

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Chitosan (CTS) Alleviates Heat-Induced Leaf Senescence in Creeping Bentgrass by Regulating Chlorophyll Metabolism, Antioxidant Defense, and the Heat Shock Pathway

Molecules ◽

10.3390/molecules26175337 ◽

2021 ◽

Vol 26 (17) ◽

pp. 5337

Author(s):

Cheng Huang ◽

Yulong Tian ◽

Bingbing Zhang ◽

Muhammad Jawad Hassan ◽

Zhou Li ◽

...

Keyword(s):

Heat Stress ◽

Heat Shock ◽

Leaf Senescence ◽

Heat Tolerance ◽

Antioxidant Defense ◽

Creeping Bentgrass ◽

Grass Species ◽

Antioxidant Enzyme Activities ◽

Ros Scavenging ◽

Chlorophyll Metabolism

Chitosan (CTS) is a deacetylated derivative of chitin that is involved in adaptive response to abiotic stresses. However, the regulatory role of CTS in heat tolerance is still not fully understood in plants, especially in grass species. The aim of this study was to investigate whether the CTS could reduce heat-induced senescence and damage to creeping bentgrass associated with alterations in antioxidant defense, chlorophyll (Chl) metabolism, and the heat shock pathway. Plants were pretreated exogenously with or without CTS (0.1 g L−1) before being exposed to normal (23/18 °C) or high-temperature (38/33 °C) conditions for 15 days. Heat stress induced detrimental effects, including declines in leaf relative water content and photochemical efficiency, but significantly increased reactive oxygen species (ROS) accumulation, membrane lipid peroxidation, and Chl loss in leaves. The exogenous application of CTS significantly alleviated heat-induced damage in creeping bentgrass leaves by ameliorating water balance, ROS scavenging, the maintenance of Chl metabolism, and photosynthesis. Compared to untreated plants under heat stress, CTS-treated creeping bentgrass exhibited a significantly higher transcription level of genes involved in Chl biosynthesis (AsPBGD and AsCHLH), as well as a lower expression level of Chl degradation-related gene (AsPPH) and senescence-associated genes (AsSAG12, AsSAG39, Asl20, and Ash36), thus reducing leaf senescence and enhancing photosynthetic performance under heat stress. In addition, the foliar application of CTS significantly improved antioxidant enzyme activities (SOD, CAT, POD, and APX), thereby effectively reducing heat-induced oxidative damage. Furthermore, heat tolerance regulated by the CTS in creeping bentgrass was also associated with the heat shock pathway, since AsHSFA-6a and AsHSP82 were significantly up-regulated by the CTS during heat stress. The potential mechanisms of CTS-regulated thermotolerance associated with other metabolic pathways still need to be further studied in grass species.

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Humic acid enhances heat stress tolerance via transcriptional activation of Heat-Shock Proteins in Arabidopsis

Scientific Reports ◽

10.1038/s41598-020-71701-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Joon-Yung Cha ◽

Sang-Ho Kang ◽

Imdad Ali ◽

Sang Cheol Lee ◽

Myung Geun Ji ◽

...

Keyword(s):

Heat Stress ◽

Humic Acid ◽

Heat Shock ◽

Stress Tolerance ◽

Transcriptional Activation ◽

Molecular Mechanisms ◽

Agronomic Traits ◽

Enrichment Analysis ◽

Gene Families ◽

Heat Stress Tolerance

Abstract Humic acid (HA) is composed of a complex supramolecular association and is produced by humification of organic matters in soil environments. HA not only improves soil fertility, but also stimulates plant growth. Although numerous bioactivities of HA have been reported, the molecular evidences have not yet been elucidated. Here, we performed transcriptomic analysis to identify the HA-prompted molecular mechanisms in Arabidopsis. Gene ontology enrichment analysis revealed that HA up-regulates diverse genes involved in the response to stress, especially to heat. Heat stress causes dramatic induction in unique gene families such as Heat-Shock Protein (HSP) coding genes including HSP101, HSP81.1, HSP26.5, HSP23.6, and HSP17.6A. HSPs mainly function as molecular chaperones to protect against thermal denaturation of substrates and facilitate refolding of denatured substrates. Interestingly, wild-type plants grown in HA were heat-tolerant compared to those grown in the absence of HA, whereas Arabidopsis HSP101 null mutant (hot1) was insensitive to HA. We also validated that HA accelerates the transcriptional expression of HSPs. Overall, these results suggest that HSP101 is a molecular target of HA promoting heat-stress tolerance in Arabidopsis. Our transcriptome information contributes to understanding the acquired genetic and agronomic traits by HA conferring tolerance to environmental stresses in plants.

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Mechanisms of plant adaptation/memory in rice seedlings under arsenic and heat stress: expression of heat-shock protein gene HSP70

AoB Plants ◽

10.1093/aobpla/plq023 ◽

2010 ◽

Vol 2010 ◽

Cited By ~ 17

Author(s):

Alakananda Goswami ◽

Rahul Banerjee ◽

Sanghamitra Raha

Keyword(s):

Heat Stress ◽

Heat Shock ◽

Heat Shock Protein ◽

Protein Gene ◽

Rice Seedlings ◽

Plant Adaptation ◽

Heat Shock Protein Gene

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Melatonin Ameliorates Thermotolerance in Soybean Seedling through Balancing Redox Homeostasis and Modulating Antioxidant Defense, Phytohormones and Polyamines Biosynthesis

Molecules ◽

10.3390/molecules26175116 ◽

2021 ◽

Vol 26 (17) ◽

pp. 5116

Author(s):

Muhammad Imran ◽

Muhammad Aaqil Khan ◽

Raheem Shahzad ◽

Saqib Bilal ◽

Murtaza Khan ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Heat Stress ◽

High Temperature ◽

Heat Shock ◽

Plant Growth ◽

Growth And Development ◽

Antioxidant Defense ◽

Plant Growth And Development ◽

Positive Effects ◽

Soybean Plants

Global warming is impacting the growth and development of economically important but sensitive crops, such as soybean (Glycine max L.). Using pleiotropic signaling molecules, melatonin can relieve the negative effects of high temperature by enhancing plant growth and development as well as modulating the defense system against abiotic stresses. However, less is known about how melatonin regulates the phytohormones and polyamines during heat stress. Our results showed that high temperature significantly increased ROS and decreased photosynthesis efficiency in soybean plants. Conversely, pretreatment with melatonin increased plant growth and photosynthetic pigments (chl a and chl b) and reduced oxidative stress via scavenging hydrogen peroxide and superoxide and reducing the MDA and electrolyte leakage contents. The inherent stress defense responses were further strengthened by the enhanced activities of antioxidants and upregulation of the expression of ascorbate–glutathione cycle genes. Melatonin mitigates heat stress by increasing several biochemicals (phenolics, flavonoids, and proline), as well as the endogenous melatonin and polyamines (spermine, spermidine, and putrescine). Furthermore, the positive effects of melatonin treatment also correlated with a reduced abscisic acid content, down-regulation of the gmNCED3, and up-regulation of catabolic genes (CYP707A1 and CYP707A2) during heat stress. Contrarily, an increase in salicylic acid and up-regulated expression of the defense-related gene PAL2 were revealed. In addition, melatonin induced the expression of heat shock protein 90 (gmHsp90) and heat shock transcription factor (gmHsfA2), suggesting promotion of ROS detoxification via the hydrogen peroxide-mediated signaling pathway. In conclusion, exogenous melatonin improves the thermotolerance of soybean plants and enhances plant growth and development by activating antioxidant defense mechanisms, interacting with plant hormones, and reprogramming the biochemical metabolism.

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CaHsfA1d Improves Plant Thermotolerance via Regulating the Expression of Stress- and Antioxidant-Related Genes

International Journal of Molecular Sciences ◽

10.3390/ijms21218374 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8374

Author(s):

Wen-Xian Gai ◽

Xiao Ma ◽

Yang Li ◽

Jing-Jing Xiao ◽

Abid Khan ◽

...

Keyword(s):

Heat Stress ◽

Heat Shock ◽

High Temperatures ◽

Regulatory Mechanism ◽

Dynamic Balance ◽

Transcription Activator ◽

Glutathione S Transferase ◽

Class A ◽

Transgenic Lines ◽

Heat Stress Tolerance

Heat shock transcription factor (Hsf) plays an important role in regulating plant thermotolerance. The function and regulatory mechanism of CaHsfA1d in heat stress tolerance of pepper have not been reported yet. In this study, phylogenetic tree and sequence analyses confirmed that CaHsfA1d is a class A Hsf. CaHsfA1d harbored transcriptional function and predicted the aromatic, hydrophobic, and acidic (AHA) motif mediated function of CaHsfA1d as a transcription activator. Subcellular localization assay showed that CaHsfA1d protein is localized in the nucleus. The CaHsfA1d was transcriptionally up-regulated at high temperatures and its expression in the thermotolerant pepper line R9 was more sensitive than that in thermosensitive pepper line B6. The function of CaHsfA1d under heat stress was characterized in CaHsfA1d-silenced pepper plants and CaHsfA1d-overexpression Arabidopsis plants. Silencing of the CaHsfA1d reduced the thermotolerance of the pepper, while CaHsfA1d-overexpression Arabidopsis plants exhibited an increased insensitivity to high temperatures. Moreover, the CaHsfA1d maintained the H2O2 dynamic balance under heat stress and increased the expression of Hsfs, Hsps (heat shock protein), and antioxidant gene AtGSTU5 (glutathione S-transferase class tau 5) in transgenic lines. Our findings clearly indicate that CaHsfA1d improved the plant thermotolerance via regulating the expression of stress- and antioxidant-related genes.

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