Water deficit has a negative effect on the physiological aspects of plants, such as stomatal closure and consequent decline in photosynthetic carbon assimilation. Numerous water deficit mitigation strategies have been investigated, such as the use of bioregulators to minimize the damage caused. This study aimed at assessing the effects of brassinosteroids on the physiological aspects of a & ccedil;a & iacute; seedlings in inducing drought tolerance. The experiment was conducted using two water conditions (well-watered and water-deficit plants) and three brassinosteroid concentrations (0, 0.05 and 0.10 mu M of 24-epibrassinolide-EBL), with six repetitions. At 120 days, seedlings were transplanted to pots and watered, leaving the soil near field capacity for 56 days. Next, a group of plants were well-watered, and another submitted to water deficit for 18 days. Water deficit reduced gas exchange and photosynthetic efficiency with a lower decrease at EBL concentrations of 0.05 and 0.10 mu M, while larger declines were observed in plants without EBL. Relative water content and leaf succulence were maintained in water-deficit plants, while proline content rose, mainly with 0.10 mu M of EBL. Applying EBL also improved water use efficiency and maintained the leaf chlorophyll and stem dry matter of stressed plants. It was concluded that leaf brassinosteroid application alleviate of harmful effects of water deficit in young a & ccedil;a & iacute; plants, promoting proline accumulation, which increases water use efficiency, and maintaining photosynthetic pigments and water status, contributing to improving drought tolerance in a & ccedil;a & iacute;.

This study investigates the role of 24-epibrassinolide (BR, 10- 2 mu M) in mitigating arsenic (As)-induced stress in maize (Zea mays L. cv. 704). Seedlings were exposed to As at concentrations of 0, 5, 10, 25, 50, 100, and 250 mu M, with or without BR application. Arsenic exposure increased oxidative damage markers such as MDA and H2O2 while BR treatment significantly enhanced antioxidant enzymes activities including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione Stransferase (GST), reducing reactive oxygen species (ROS) levels, and minimizing oxidative damage. Additionally, BR significantly increased proline, phenolic compounds, flavonoids, and soluble sugars, contributing to osmoprotection and stress tolerance, as well as enhancing FRAP and DPPH antioxidant activities. Furthermore, BR increased amino acids (AAs) such as proline (Pro), cysteine (Cys), glutamine (Gln), and glutamate (Glu). Gene expression analysis revealed significant upregulation of detoxification-related genes including cytochrome P450 monooxygenases (CYPs), GT1, GST27 and multidrug resistance-associated proteins (MRPs) under BR treatment. These findings suggest that BR enhances maize tolerance to As toxicity by activating detoxification pathways, improving antioxidant defense, and stabilizing metabolic processes. The results underscore the potential application of BR in sustainable agriculture to improve crop resilience in As-contaminated soils.

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 mu M 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.