Amelioration of Salt Stress on Bermudagrass by the Fungus Aspergillus aculeatus

There is considerable evidence that plant abiotic-stress tolerance can be evoked by the exploitation of a globally abundant microbe. A. aculeatus, which was initially isolated from the rhizosphere of bermudagrass, has been shown to increase heavy metal tolerance in turfgrasses. Here, we report on the potential of A. aculeatus to induce tolerance to salt stress in bermudagrass. Physiological markers for salt stress, such as plant growth rate, lipid peroxidation, photosynthesis, and ionic homeostasis were assessed. Results indicated that strain A. aculeatus produced indole-3-acetic acid (IAA) and siderophores and exhibited a greater capacity for Na+ absorption under salt stress. The plant inoculation by A. aculeatus increased plant growth and attenuated the NaCl-induced lipid peroxidation in roots and leaves of bermudagrass. The fungus significantly elevated the amount of IAA and glutathione and slightly enhanced photosynthetic efficiency of salt-treated bermudagrass. Tissues of inoculated plants had significantly increased concentrations of K+ but lower Na+ concentrations than those of uninoculated regimes. It appears that the role of A. aculeatus in alleviating bermudagrass salt stress is partly to produce IAA, to increase the activity of antioxidases, to absorb Na+ by fungal hyphae, and to prevent the plant from ionic homeostasis disruption.

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Effect of Lead and Copper on Photosynthetic Apparatus in Citrus (Citrus aurantium L.) Plants. The Role of Antioxidants in Oxidative Damage as a Response to Heavy Metal Stress

Plants ◽

10.3390/plants10010155 ◽

2021 ◽

Vol 10 (1) ◽

pp. 155

Author(s):

Anastasia Giannakoula ◽

Ioannis Therios ◽

Christos Chatzissavvidis

Keyword(s):

Oxidative Stress ◽

Lipid Peroxidation ◽

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Membrane Integrity ◽

Photosynthetic Apparatus ◽

Heavy Metal Stress ◽

Photosynthetic Parameters ◽

Citrus Aurantium

Photosynthetic changes and antioxidant activity to oxidative stress were evaluated in sour orange (Citrus aurantium L.) leaves subjected to lead (Pb), copper (Cu) and also Pb + Cu toxicity treatments, in order to elucidate the mechanisms involved in heavy metal tolerance. The simultaneous effect of Pb− and Cu on growth, concentration of malondialdehyde (MDA), hydrogen peroxide (H2O2), chlorophylls, flavonoids, carotenoids, phenolics, chlorophyll fluorescence and photosynthetic parameters were examined in leaves of Citrus aurantium L. plants. Exogenous application of Pb and Cu resulted in an increase in leaf H2O2 and lipid peroxidation (MDA). Toxicity symptoms of both Pb and Cu treated plants were stunted growth and decreased pigments concentration. Furthermore, photosynthetic activity of treated plants exhibited a significant decline. The inhibition of growth in Pb and Cu-treated plants was accompanied by oxidative stress, as indicated by the enhanced lipid peroxidation and the high H2O2 concentration. Furthermore, antioxidants in citrus plants after exposure to high Pb and Cu concentrations were significantly increased compared to control and low Pb and Cu treatments. In conclusion, this study indicates that Pb and Cu promote lipid peroxidation, disrupt membrane integrity, reduces growth and photosynthesis and inhibit mineral nutrition. Considering the potential for adverse human health effects associated with high concentrations of Pb and Cu contained in edible parts of citrus plants the study signals that it is important to conduct further research into the accessibility and uptake of the tested heavy metals in the soil and whether they pose risks to humans.

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Down-Regulation of SlGRAS10 in Tomato Confers Abiotic Stress Tolerance

Genes ◽

10.3390/genes12050623 ◽

2021 ◽

Vol 12 (5) ◽

pp. 623

Author(s):

Sidra Habib ◽

Yee Yee Lwin ◽

Ning Li

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Plant Growth ◽

Stress Tolerance ◽

Abiotic Stresses ◽

Abiotic Stress Tolerance ◽

Functional Characterization ◽

Flavonoid Biosynthesis ◽

Ros Scavenging ◽

Down Regulation

Adverse environmental factors like salt stress, drought, and extreme temperatures, cause damage to plant growth, development, and crop yield. GRAS transcription factors (TFs) have numerous functions in biological processes. Some studies have reported that the GRAS protein family plays significant functions in plant growth and development under abiotic stresses. In this study, we demonstrated the functional characterization of a tomato SlGRAS10 gene under abiotic stresses such as salt stress and drought. Down-regulation of SlGRAS10 by RNA interference (RNAi) produced dwarf plants with smaller leaves, internode lengths, and enhanced flavonoid accumulation. We studied the effects of abiotic stresses on RNAi and wild-type (WT) plants. Moreover, SlGRAS10-RNAi plants were more tolerant to abiotic stresses (salt, drought, and Abscisic acid) than the WT plants. Down-regulation of SlGRAS10 significantly enhanced the expressions of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) to reduce the effects of reactive oxygen species (ROS) such as O2− and H2O2. Malondialdehyde (MDA) and proline contents were remarkably high in SlGRAS10-RNAi plants. Furthermore, the expression levels of chlorophyll biosynthesis, flavonoid biosynthesis, and stress-related genes were also enhanced under abiotic stress conditions. Collectively, our conclusions emphasized the significant function of SlGRAS10 as a stress tolerate transcription factor in a certain variety of abiotic stress tolerance by enhancing osmotic potential, flavonoid biosynthesis, and ROS scavenging system in the tomato plant.

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Role of Nitric Oxide in Plant Abiotic Stress Tolerance

Improving Abiotic Stress Tolerance in Plants ◽

10.1201/9780429027505-8 ◽

2020 ◽

pp. 131-154

Author(s):

Gábor Feigl ◽

Árpád Molnár ◽

Dóra Oláh ◽

Zsuzsanna Kolbert

Keyword(s):

Nitric Oxide ◽

Abiotic Stress ◽

Stress Tolerance ◽

Abiotic Stress Tolerance ◽

Plant Abiotic Stress

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Mechanisms of Response to Salt Stress in Oleander (Nerium oleander L.)

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Horticulture ◽

10.15835/buasvmcn-hort:12287 ◽

2016 ◽

Vol 73 (2) ◽

pp. 249

Author(s):

Dinesh Kumar ◽

Mohamad Al Hassan ◽

Oscar Vicente ◽

Veena Agrawal ◽

Monica Boscaiu

Keyword(s):

Salt Stress ◽

Abiotic Stress Tolerance ◽

Soluble Sugar ◽

Soluble Sugars ◽

Nerium Oleander ◽

Antioxidant Systems ◽

Change Scenario ◽

Antioxidant Compounds ◽

Stress Dependent

Elucidating the mechanisms of abiotic stress tolerance in different species will help to develop more resistant plant varieties, contributing to improve agricultural production in a climate change scenario. Basic responses to salt stress, dependent on osmolyte accumulation and activation of antioxidant systems, have been studied in Nerium oleander, a xerophytic species widely used as ornamental. Salt strongly inhibited growth, but the plants survived one-month treatments with quite high NaCl concentrations, up to 800 mM, indicating the the species is relatively resistant to salt stress, in addition to drought. Levels of proline, glycine betaine and soluble sugars increased only slightly in the presence of salt; however, soluble sugar absolute contents were much higher than those of the other osmolytes, suggesting a functional role of these compounds in osmotic adjustment, and the presence of constitutive mechanisms of response to salt stress. High salinity generated oxidative stress in the plants, as shown by the increase of malondialdehyde levels. Antioxidant systems, enzymatic and non-enzymatic, are generally activated in response to salt stress; in oleander, they do not seem to include total phenolics or flavonoids, antioxidant compounds which did not accumulate significantly in salt-trated plants

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Role of Phytochelatins (PCs), Metallothioneins (MTs), and Heavy Metal ATPase (HMA) Genes in Heavy Metal Tolerance

Fungal Biology - Mycoremediation and Environmental Sustainability ◽

10.1007/978-3-319-77386-5_2 ◽

2018 ◽

pp. 39-60 ◽

Cited By ~ 4

Author(s):

Khushboo Chaudhary ◽

Swati Agarwal ◽

Suphiya Khan

Keyword(s):

Heavy Metal ◽

Metal Tolerance ◽

Heavy Metal Tolerance ◽

Heavy Metal Atpase

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Arabidopsis Plastid-RNA Polymerase RPOTp Is Involved in Abiotic Stress Tolerance

Plants ◽

10.3390/plants9070834 ◽

2020 ◽

Vol 9 (7) ◽

pp. 834

Author(s):

Abel Lidón-Soto ◽

Eva Núñez-Delegido ◽

Iván Pastor-Martínez ◽

Pedro Robles ◽

Víctor Quesada

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Rna Polymerase ◽

Stress Tolerance ◽

Abiotic Stress Tolerance ◽

Retrograde Signaling ◽

Compensatory Mechanism ◽

Transcript Levels ◽

Plastid Rna Polymerase

Plastid gene expression (PGE) must adequately respond to changes in both development and environmental cues. The transcriptional machinery of plastids in land plants is far more complex than that of prokaryotes. Two types of DNA-dependent RNA polymerases transcribe the plastid genome: a multimeric plastid-encoded polymerase (PEP), and a monomeric nuclear-encoded polymerase (NEP). A single NEP in monocots (RPOTp, RNA polymerase of the T3/T7 phage-type) and two NEPs in dicots (plastid-targeted RPOTp, and plastid- and mitochondrial-targeted RPOTmp) have been hitherto identified. To unravel the role of PGE in plant responses to abiotic stress, we investigated if Arabidopsis RPOTp could function in plant salt tolerance. To this end, we studied the sensitivity of T-DNA mutants scabra3-2 (sca3-2) and sca3-3, defective in the RPOTp gene, to salinity, osmotic stress and the phytohormone abscisic acid (ABA) required for plants to adapt to abiotic stress. sca3 mutants were hypersensitive to NaCl, mannitol and ABA during germination and seedling establishment. Later in development, sca3 plants displayed reduced sensitivity to salt stress. A gene ontology (GO) analysis of the nuclear genes differentially expressed in the sca3-2 mutant (301) revealed that many significantly enriched GO terms were related to chloroplast function, and also to the response to several abiotic stresses. By quantitative RT-PCR (qRT-PCR), we found that genes LHCB1 (LIGHT-HARVESTING CHLOROPHYLL a/b-BINDING1) and AOX1A (ALTERNATIVE OXIDASE 1A) were respectively down- and up-regulated in the Columbia-0 (Col-0) salt-stressed plants, which suggests the activation of plastid and mitochondria-to-nucleus retrograde signaling. The transcript levels of genes RPOTp, RPOTmp and RPOTm significantly increased in these salt-stressed seedlings, but this enhanced expression did not lead to the up-regulation of the plastid genes solely transcribed by NEP. Similar to salinity, carotenoid inhibitor norflurazon (NF) also enhanced the RPOTp transcript levels in Col-0 seedlings. This shows that besides salinity, inhibition of chloroplast biogenesis also induces RPOTp expression. Unlike salt and NF, the NEP genes were significantly down-regulated in the Col-0 seedlings grown in ABA-supplemented media. Together, our findings demonstrate that RPOTp functions in abiotic stress tolerance, and RPOTp is likely regulated positively by plastid-to-nucleus retrograde signaling, which is triggered when chloroplast functionality is perturbed by environmental stresses, e.g., salinity or NF. This suggests the existence of a compensatory mechanism, elicited by impaired chloroplast function. To our knowledge, this is the first study to suggest the role of a nuclear-encoded plastid-RNA polymerase in salt stress tolerance in plants.

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