Oxidative stress and plant responses to pathogens under drought conditions

It is no longer doubted that calcium functions as a second messenger in animals and plants. This is only possible because cells maintain cytosolic calcium concentrations many orders of magnitude below that of extracellular or organelle calcium. Environmental stimuli are perceived by receptor proteins which trigger transient elevation of cytosolic calcium using internal or external sources. The spatial and temporal distribution and the magnitude of calcium elevation determines the specific cellular response at the molecular level (Cheek 1991). The fine balance of cytosolic calcium homeostasis in animal cells is highly sensitive to oxidising conditions (Duncan 1991). Elevated cytosolic calcium resulting from oxidative perturbation of calcium homeostasis is believed to be responsible for the subsequent cellular injury and death (Nicotera et al. 1991). Transient stimulation of cytosolic calcium in sublethal oxidative stress may be a mechanism by which oxidative attack is perceived by the animal cell (Nicotera et al. 1991). Our understanding of oxidative stress and plant responses to it would be greatly advanced if it can be shown that similar processes occur in plant cells. This paper briefly presents the mechanism of oxidative disruption of calcium homeostasis in animal cells and summarises the evidence that the same scenario applies to plants.

Download Full-text

Oxidative Stress in Plants Under Drought Conditions and the Role of Different Enzymes

Enzyme Engineering ◽

10.4172/2329-6674.1000136 ◽

2016 ◽

Vol 5 (1) ◽

Cited By ~ 7

Author(s):

Leonora Mansur Mattos ◽

Celso Luiz Moretti

Keyword(s):

Oxidative Stress ◽

Drought Conditions

Download Full-text

Overexpression of MdATG8i Enhances Drought Tolerance by Alleviating Oxidative Damage and Promoting Water Uptake in Transgenic Apple

International Journal of Molecular Sciences ◽

10.3390/ijms22115517 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5517

Author(s):

Xin Jia ◽

Xiaoqing Gong ◽

Xumei Jia ◽

Xianpeng Li ◽

Yu Wang ◽

...

Keyword(s):

Drought Stress ◽

Drought Tolerance ◽

Oxidative Damage ◽

Water Uptake ◽

Transcript Level ◽

Root Water Uptake ◽

Plant Responses ◽

Severe Drought ◽

Root Hydraulic Conductivity ◽

Drought Conditions

Water deficit adversely affects apple (Malus domestica) productivity on the Loess Plateau. Autophagy plays a key role in plant responses to unfavorable environmental conditions. Previously, we demonstrated that a core apple autophagy-related protein, MdATG8i, was responsive to various stresses at the transcript level. Here, we investigated the function of this gene in the response of apple to severe drought and found that its overexpression (OE) significantly enhanced drought tolerance. Under drought conditions, MdATG8iOE apple plants exhibited less drought-related damage and maintained higher photosynthetic capacities compared with the wild type (WT). The accumulation of ROS (reactive oxygen species) was lower in OE plants under drought stress and was accompanied by higher activities of antioxidant enzymes. Besides, OE plants accumulated lower amounts of insoluble or oxidized proteins but greater amounts of amino acids and flavonoid under severe drought stress, probably due to their enhanced autophagic activities. Particularly, MdATG8iOE plants showed higher root hydraulic conductivity than WT plants did under drought conditions, indicating the enhanced ability of water uptake. In summary, the overexpression of MdATG8i alleviated oxidative damage, modulated amino acid metabolism and flavonoid synthesis, and improved root water uptake, ultimately contributing to enhanced drought tolerance in apple.

Download Full-text

Foliar Sprayed Green Zinc Oxide Nanoparticles Mitigate Drought-Induced Oxidative Stress in Tomato

Plants ◽

10.3390/plants10112400 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2400

Author(s):

Manal El-Zohri ◽

Naseem A. Al-Wadaani ◽

Sameera O. Bafeel

Keyword(s):

Oxidative Stress ◽

Zinc Oxide ◽

Drought Stress ◽

Zinc Oxide Nanoparticles ◽

Foliar Spray ◽

Oxide Nanoparticles ◽

Severe Drought ◽

Zno Nps ◽

Drought Conditions ◽

Tomato Growth

This study explored the effectiveness of green zinc oxide nanoparticles (ZnO-NPs) foliar spray on tomato growth and oxidative stress relief under drought conditions. Tomato plant subjected to four water regimes (100, 75, 50, and 25% FC), and in the same while seedlings were sprayed with 25, 50, and 100 mg/L green ZnO-NPs. The results showed that tomato growth parameters reduced significantly by increasing drought stress levels, while ZnO-NPs enhanced plant growth under all studied drought levels. Out of three ZnO-NPs concentrations tested, 25 and 50 mg/L ZnO-NPs proved to be the optimum treatments for alleviating drought stress. They increased shoot and root biomass compared to untreated controls. Application of 25 and 50 mg/L ZnO-NPs enhanced shoot dry weight by about 2–2.5-fold, respectively, under severe drought conditions (25%) compared to ZnO-NPs untreated plants. The application of 25 and 50 mg/L green ZnO-NPs decreased the drought-induced oxidative stress as indicated by the reduction in malondialdehyde and hydrogen peroxide concentrations compared to untreated controls. While 100 mg/L ZnO-NPs further increased oxidative stress. The beneficial effects of ZnO-NPs were evident in the plants’ defensive state, in which the concentration of ascorbic acid, free phenols, and the activity of superoxide dismutase, catalase, and ascorbate peroxidase were maintained at higher levels compared to NPs-untreated plants. At severe drought conditions, 25 mg/L ZnO-NPs induced SOD, CAT, and APX activity by about 3.99-, 3.23-, and 2.82-fold of their corresponding controls, respectively. Likewise, at 25% FC, SOD, CAT, and APX activity increased with 50 mg/L ZnO-NPs by about 4.58-, 3.57-, and 3.25-fold consecutively compared with their respective controls. Therefore, foliar use of green ZnO-NPs at lower concentrations might be suggested as an efficient way for enhancing tomato tolerance to drought stress.

Download Full-text

Transcriptome analysis of drought-tolerant sorghum genotype SC56 in response to water stress reveals an oxidative stress defense strategy

10.21203/rs.2.13124/v1 ◽

2019 ◽

Author(s):

Farida Olden ◽

Arthur G. Hunt ◽

Randy Dinkins

Keyword(s):

Oxidative Stress ◽

Water Stress ◽

Drought Tolerance ◽

Stress Tolerance ◽

Differential Expression ◽

Expression Analysis ◽

Transcriptome Analysis ◽

Differential Expression Analysis ◽

Drought Tolerant ◽

Drought Conditions

Abstract Background Drought tolerance is a crucial trait for crops to curtail the yield loss inflicted by water stress to crops, yet genetic improvement efforts are challenged by the complexity of this character. The adaptation of sorghum to abiotic stress, its genotypic variability, and relatively small genome make this species well-suited to dissect the molecular basis of drought tolerance. One efficient approach to this question is the use of differential transcriptome analysis, which provides a snapshot of the processes underlying drought response as well as genes that might be determinants of the drought tolerance trait. Results RNA sequencing was used to compare the transcriptome profiles of two sorghum lines, the drought-tolerant SC56 and the drought-sensitive Tx7000. The differential expression analysis revealed unambiguous genotypic disparities, including a massive increase of upregulated transcripts in SC56. Concomitantly, gene ontology enrichment showed that SC56 biologically outperformed Tx7000 in wet conditions, since it upregulated processes driving growth and guaranteeing homeostasis. The drought tolerance of SC56 seems to be an intrinsic trait that occurs through the overexpression of stress tolerance genes in wet conditions, notably those acting in defense against oxidative stress (SOD1, SOD2, VTC1, MDAR1, MSRB2, and ABC1K1). Under drought conditions, SC56 enhanced its transmembrane transport and maintained growth-promoting mechanisms similar to those implemented under wet conditions. SC56 also appears to preserve its biological function, in a limiting environment, by relying on reported validated stress tolerance genes that heighten the antioxidant capacity (SOD1, RCI3, VTE1, UCP1, FD1, and FD2), regulatory factors (CIPK1 and CRK7), and repressors of premature senescence (SAUL1). Of the stress tolerance genes overexpressed under both wet and drought conditions, DHAR2 might be a key determinant of drought tolerance since its role in recycling ascorbic acid was described to be directly linked to protection against reactive oxygen species-mediated damage, positive effects on photosynthetic activity, higher rate of plant growth, and delayed leaf aging. Conclusion The differential expression analysis uncovered biological processes which upregulation enables SC56 to be a better accumulator of biomass and connects the drought tolerance trait to key stress tolerance genes, making this genotype a judicious choice for isolation of tolerance genes.

Download Full-text