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21 pages, 4206 KiB

Open AccessArticle

Differential Modulation of Brassinosteroid and Ethylene Signalling Systems by Native and Constitutively Active Forms of the AtCPK1 Gene in Transgenic Tobacco Plants Under Heat Stress

by Olga A. Tikhonova, Valeria P. Grigorchuk, Evgenia V. Brodovskaya and Galina N. Veremeichik

Plants 2025, 14(7), 1032; https://doi.org/10.3390/plants14071032 - 26 Mar 2025

Viewed by 363

Abstract

Among other calcium decoders, Ca²⁺-dependent protein kinases (CDPK) stands out for its ability, depending on calcium levels, to activate key components of the defence system. However, calcium dependence prevents the effective use of CDPKs in comprehensive investigations of their functions. Previously, [...] Read more.

Among other calcium decoders, Ca²⁺-dependent protein kinases (CDPK) stands out for its ability, depending on calcium levels, to activate key components of the defence system. However, calcium dependence prevents the effective use of CDPKs in comprehensive investigations of their functions. Previously, we showed that a modified constitutively active form of AtCPK1 improved heat tolerance in tobacco plants. At present, the role of calcium ions and their decoders in the regulation of heat tolerance is not fully understood. The response of plant cells to excessive temperature increases is regulated by complex interactions of hormonal signalling systems, among which the least studied is BR signalling. In the present work, we investigated the role of CDPK in the interactions of BR and ET signalling during heat stress. The use of a modified calcium-independent form of AtCPK1 in this work allowed us to answer a number of questions. We showed that dependence on heat-induced calcium ion currents determines the priority of the activation of ABA signalling. Thus, CPK-dependent activation of ABA signalling may not lead to an insufficient response from BR and ET signalling. Modified CPK1 activates BR signalling, which has a positive effect on the tolerance of transgenic plants to increased temperature. The obtained data shed light on heat-associated molecular processes and can draw attention to the possibility of using intradomain modifications of CDPK both for a comprehensive study of its functional features and as a bioengineering tool. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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16 pages, 1491 KiB

Open AccessArticle

A Comparative Analysis of the Effect of 24-Epibrassinolide on the Tolerance of Wheat Cultivars with Different Drought Adaptation Strategies Under Water Deficit Conditions

by Azamat Avalbaev, Ruslan Yuldashev, Anton Plotnikov and Chulpan Allagulova

Plants 2025, 14(6), 869; https://doi.org/10.3390/plants14060869 - 10 Mar 2025

Viewed by 502

Abstract

Drought is a serious environmental challenge that reduces the productivity of valuable crops, including wheat. Brassinosteroids (BRs) is a group of phytohormones that have been used to enhance wheat drought tolerance. Wheat cultivars with different adaptation strategies could have their own specific drought [...] Read more.

Drought is a serious environmental challenge that reduces the productivity of valuable crops, including wheat. Brassinosteroids (BRs) is a group of phytohormones that have been used to enhance wheat drought tolerance. Wheat cultivars with different adaptation strategies could have their own specific drought tolerance mechanisms, and could react differently to treatment with growth regulators. In this work, the effect of seed pretreatment with 0.4 µM 24-epibrassinolide (EBR) was investigated in two wheat (Triticum aestivum L.) cultivars contrasting in drought behavior, tolerant Ekada 70 (cv. E70) and sensitive Zauralskaya Zhemchuzhina (cv. ZZh), in early ontogenesis under dehydration (PEG-6000) or soil drought conditions. EBR pretreatment mitigated the stress-induced inhibition of seedling emergence and growth, as well as membrane damage in cv.E70 but not in ZZh. An enzyme-linked immunosorbent assay (ELISA) revealed substantial changes in hormonal balance associated with ABA accumulation and a drop in the levels of IAA and cytokinins (CKs) in drought-subjected seedlings of both cultivars, especially ZZh. EBR-pretreatment reduced drought-induced hormone imbalance in cv. E70, while it did not have the same effect on ZZh. EBR-induced changes in the content of wheat germ agglutinin (WGA) belonging to the protective proteins in E70 seedlings suggest its contribution to EBR-dependent adaptive responses. The absence of a detectable protective effect of EBR on the ZZh cultivar may be associated with its insensitivity to pre-sowing EBR treatment. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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14 pages, 9955 KiB

Open AccessArticle

Brassinosteroids Render Cell Walls Softer but Less Extensible in Growing Arabidopsis Hypocotyls

by Dmitry V. Suslov, Alexandra N. Ivanova, Daria Balcerowicz, Mariia S. Tarasova, Nuria K. Koteyeva and Kris Vissenberg

Plants 2025, 14(2), 176; https://doi.org/10.3390/plants14020176 - 10 Jan 2025

Viewed by 2948

Abstract

Cell wall extensibility is a key biophysical characteristic that defines the rate of plant cell growth. It depends on the wall structure and is controlled by numerous proteins that cut and/or (re)form links between the wall constituents. Cell wall extensibility is currently estimated [...] Read more.

Cell wall extensibility is a key biophysical characteristic that defines the rate of plant cell growth. It depends on the wall structure and is controlled by numerous proteins that cut and/or (re)form links between the wall constituents. Cell wall extensibility is currently estimated by different in vitro biomechanical tests. We used the creep method, in which isolated cell walls are extended under a constant load and their time-dependent deformation (creep) is recorded to reveal the biophysical basis of growth inhibition of Arabidopsis thaliana hypocotyls in the presence of 24-epibrassinolide (EBL), one of the most active natural brassinosteroids. We found that EBL rendered the walls of hypocotyl cells softer, i.e., more deformable under mechanical force, which was revealed using heat-inactivated cell walls to eliminate endogenous activities of cell-wall-loosening/tightening proteins. This effect was caused by the altered arrangement of cellulose microfibrils. At the same time, EBL made the walls less extensible, which was detected with native walls under conditions optimized for activities of endogenous cell-wall-loosening proteins. These apparently conflicting changes in the wall mechanics can be an adaptation by which EBL enables plant cells to grow under stress conditions. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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17 pages, 3328 KiB

Open AccessArticle

Preliminary Treatment by Exogenous 24-Epibrassinolide Influences Burning-Induced Electrical Signals and Following Photosynthetic Responses in Pea (Pisum sativum L.)

by Ekaterina Sukhova, Lyubov Yudina, Elizaveta Kozlova and Vladimir Sukhov

Plants 2024, 13(23), 3292; https://doi.org/10.3390/plants13233292 - 23 Nov 2024

Viewed by 802

Abstract

Long-distance electrical signals (ESs) are an important mechanism of induction of systemic adaptive changes in plants under local action of stressors. ES-induced changes in photosynthesis and transpiration play a key role in these responses increasing plant tolerance to action of adverse factors. As [...] Read more.

Long-distance electrical signals (ESs) are an important mechanism of induction of systemic adaptive changes in plants under local action of stressors. ES-induced changes in photosynthesis and transpiration play a key role in these responses increasing plant tolerance to action of adverse factors. As a result, investigating ways of regulating electrical signaling and ES-induced physiological responses is a perspective problem of plant electrophysiology. The current work was devoted to the analysis of the influence of preliminary treatment (spraying) by exogenous 24-epibrassinolide (EBL) on burning-induced ESs and following photosynthetic and transpiratory responses in pea (Pisum sativum L.). It was shown that preliminary treatment by 1 µM EBL (1 day before the experiment) increased the amplitude of burning-induced ESs (variation potentials) in leaves and decreased the time of propagation of these signals from the stem to the leaf. The EBL treatment weakly influenced the magnitudes of burning-induced decreasing the photosynthetic linear electron flow and CO₂ assimilation, but these changes were accelerated. Burning-induced changes in the cyclic electron flow around photosystem I were also affected by the EBL treatment. The influence of the EBL treatment on burning-induced changes in the stomatal water conductance was not observed. Our results show that preliminary treatment by EBL can be used for the modification of electrical signals and following photosynthetic responses in plants. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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19 pages, 2162 KiB

Open AccessArticle

Effects of Lactone- and Ketone-Brassinosteroids of the 28-Homobrassinolide Series on Barley Plants under Water Deficit

by Liliya V. Kolomeichuk, Ol’ga K. Murgan, Elena D. Danilova, Mariya V. Serafimovich, Vladimir A. Khripach, Raisa P. Litvinovskaya, Alina L. Sauchuk, Daria V. Denisiuk, Vladimir N. Zhabinskii, Vladimir V. Kuznetsov and Marina V. Efimova

Plants 2024, 13(10), 1345; https://doi.org/10.3390/plants13101345 - 13 May 2024

Cited by 2 | Viewed by 1638

Abstract

The aim of this work was to study the ability of 28-homobrassinolide (HBL) and 28-homocastasterone (HCS) to increase the resistance of barley (Hordeum vulgare L.) plants to drought and to alter their endogenous brassinosteroid status. Germinated barley seeds were treated with 0.1 [...] Read more.

The aim of this work was to study the ability of 28-homobrassinolide (HBL) and 28-homocastasterone (HCS) to increase the resistance of barley (Hordeum vulgare L.) plants to drought and to alter their endogenous brassinosteroid status. Germinated barley seeds were treated with 0.1 nM HBL or HCS solutions for two hours. A water deficit was created by stopping the watering of 7-day-old plants for the next two weeks. Plants responded to drought through growth inhibition, impaired water status, increased lipid peroxidation, differential effects on antioxidant enzymes, intense proline accumulation, altered expression of genes involved in metabolism, and decreased endogenous contents of hormones (28-homobrassinolide, B-ketones, and B-lactones). Pretreatment of plants with HBL reduced the inhibitory effect of drought on fresh and dry biomass accumulation and relative water content, whereas HCS partially reversed the negative effect of drought on fresh biomass accumulation, reduced the intensity of lipid peroxidation, and increased the osmotic potential. Compared with drought stress alone, pretreatment of plants with HCS or HBL followed by drought increased superoxide dismutase activity sevenfold or threefold and catalase activity (by 36%). The short-term action of HBL and HCS in subsequent drought conditions partially restored the endogenous B-ketone and B-lactone contents. Thus, the steroidal phytohormones HBL and HCS increased barley plant resistance to subsequent drought, showing some specificity of action. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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22 pages, 3045 KiB

Open AccessArticle

Exogenous Application of 24-Epibrassinolide Confers Saline Stress and Improves Photosynthetic Capacity, Antioxidant Defense, Mineral Uptake, and Yield in Maize

by Mahmoud F. Seleiman, Awais Ahmad, ElKamil Tola, Bushra Ahmed Alhammad, Khalid F. Almutairi, Rangaswamy Madugundu and Khalid A. Al-Gaadi

Plants 2023, 12(20), 3559; https://doi.org/10.3390/plants12203559 - 13 Oct 2023

Cited by 10 | Viewed by 1819

Abstract

Salinity is one of the major environmental stresses threatening crop production, the natural ecosystem, global food security, and the socioeconomic health of humans. Thus, the development of eco-friendly strategies to mitigate saline stress and/or enhance crop tolerance is an important issue worldwide. Therefore, [...] Read more.

Salinity is one of the major environmental stresses threatening crop production, the natural ecosystem, global food security, and the socioeconomic health of humans. Thus, the development of eco-friendly strategies to mitigate saline stress and/or enhance crop tolerance is an important issue worldwide. Therefore, this study was conducted during the summer of 2022 to investigate the potential of 24-Epibrassinolide (EBL) for mitigating saline stress and improving photosynthetic capacity, antioxidant defense systems, mineral uptake, and yield in maize (Zea mays L.) grown under a controlled hydroponic system. Three saline stress levels—S1 (control/no added NaCl), S2 (60 mM NaCl), and S3 (120 mM NaCl)—were continuously applied with nutrient solution, whereas exogenous EBL (i.e., control, 0.1 µM and 0.2 µM) was applied as exogenous application three times (i.e., 40, 55, 70 days after sowing). The experiment was designed as a split-plot in a randomized complete block design (RCBD) in which saline stress was the main factor and EBL treatment was the sub-factor. Results showed that saline stress significantly affected plant growth, physiological performance, biochemistry, antioxidant activity, and yield attributes. However, the exogenous application of EBL at 0.2 µM significantly mitigated the salt stress and thus improved plant performance even under 120 mM NaCl saline stress. For instance, as compared to untreated plants (control), 0.2 µM EBL application improved plant height (+18%), biomass (+19%), SPAD (+32%), Fv/Fm (+28%), rate of photosynthesis (+11%), carboxylation efficiency (+6%), superoxide dismutase (SOD +14%), catalase (CAT +18%), ascorbate peroxidase (APX +20%), K⁺ (+24%), 100-grain weight (+11%), and grain yield (+47%) of maize grown under salt stress. Additionally, it resulted in a 23% reduction in Na⁺ accumulation in leaves and a 25% reduction in for Na⁺/K⁺ ratio under saline stress as compared to control. Furthermore, the Pearson’s correlation and principal component analysis (PCA) highlighted the significance of exogenous EBL as saline stress mitigator in maize. Overall, our results indicated the protective effects of EBL application to the alleviation of saline stress in crop plants. However, further exploration of its mechanism of action and crop-specific response is suggested prior to commercial use in agriculture. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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16 pages, 1598 KiB

Open AccessArticle

28-Homobrassinolide Primed Seed Improved Lead Stress Tolerance in Brassica rapa L. through Modulation of Physio-Biochemical Attributes and Nutrient Uptake

by Mawra Khan, Shakil Ahmed, Nasim Ahmad Yasin, Rehana Sardar, Muhammad Hussaan, Abdel-Rhman Z. Gaafar and Faish Ullah Haider

Plants 2023, 12(20), 3528; https://doi.org/10.3390/plants12203528 - 11 Oct 2023

Cited by 4 | Viewed by 1730

Abstract

Brassinosteroids (BRs) influence a variety of physiological reactions and alleviate different biotic and abiotic stressors. Turnip seedlings were grown with the goal of further exploring and expanding their function in plants under abiotic stress, particularly under heavy metal toxicity (lead stress). This study’s [...] Read more.

Brassinosteroids (BRs) influence a variety of physiological reactions and alleviate different biotic and abiotic stressors. Turnip seedlings were grown with the goal of further exploring and expanding their function in plants under abiotic stress, particularly under heavy metal toxicity (lead stress). This study’s objective was to ascertain the role of applied 28-homobrassinolide (HBL) in reducing lead (Pb) stress in turnip plants. Turnip seeds treated with 1, 5, and 10 µM HBL and were grown-up in Pb-contaminated soil (300 mg kg⁻¹). Lead accumulation reduces biomass, growth attributes, and various biochemical parameters, as well as increasing proline content. Seed germination, root and shoot growth, and gas exchange characteristics were enhanced via HBL treatment. Furthermore, Pb-stressed seedlings had decreased total soluble protein concentrations, photosynthetic pigments, nutrition, and phenol content. Nonetheless, HBL increased chlorophyll a and chlorophyll b levels in plant, resulting in increased photosynthesis. As a result, seeds treated with HBL2 (5 µM L⁻¹) had higher nutritional contents (Mg⁺², Zn⁺², Na⁺², and K⁺¹). HBL2-treated seedlings had higher DPPH and metal tolerance indexes. This led to the conclusion that HBL2 effectively reduced Pb toxicity and improved resistance in lead-contaminated soil. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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Review

Jump to: Research

21 pages, 1297 KiB

Open AccessReview

Brassinosteroids in Micronutrient Homeostasis: Mechanisms and Implications for Plant Nutrition and Stress Resilience

by Laiba Usmani, Adiba Shakil, Iram Khan, Tanzila Alvi, Surjit Singh and Debatosh Das

Plants 2025, 14(4), 598; https://doi.org/10.3390/plants14040598 - 17 Feb 2025

Cited by 2 | Viewed by 1394

Abstract

Brassinosteroids (BRs) are crucial plant hormones that play a significant role in regulating various physiological processes, including micronutrient homeostasis. This review delves into the complex roles of BRs in the uptake, distribution, and utilization of essential micronutrients such as iron (Fe), zinc (Zn), [...] Read more.

Brassinosteroids (BRs) are crucial plant hormones that play a significant role in regulating various physiological processes, including micronutrient homeostasis. This review delves into the complex roles of BRs in the uptake, distribution, and utilization of essential micronutrients such as iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and boron (B). BRs influence the expression of key transporter genes responsible for the absorption and internal distribution of these micronutrients. For iron, BRs enhance the expression of genes related to iron reduction and transport, improve root architecture, and strengthen stress tolerance mechanisms. Regarding zinc, BRs regulate the expression of zinc transporters and support root development, thereby optimizing zinc uptake. Manganese homeostasis is managed through the BR-mediated regulation of manganese transporter genes and chlorophyll production, essential for photosynthesis. For copper, BRs influence the expression of copper transporters and maintain copper-dependent enzyme activities crucial for metabolic functions. Finally, BRs contribute to boron homeostasis by regulating its metabolism, which is vital for cell wall integrity and overall plant development. This review synthesizes recent findings on the mechanistic pathways through which BRs affect micronutrient homeostasis and discusses their implications for enhancing plant nutrition and stress resilience. Understanding these interactions offers valuable insights into strategies for improving micronutrient efficiency in crops, which is essential for sustainable agriculture. This comprehensive analysis highlights the significance of BRs in micronutrient management and provides a framework for future research aimed at optimizing nutrient use and boosting plant productivity. Full article

(This article belongs to the Special Issue Brassinosteroids: Signaling and Role in Plant Responses to Biotic and Abiotic Stresses)

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