Background and aimsContinuous cropping obstacles (CCOs) are frequently encountered during the cultivation of Lagenaria siceraria (L. siceraria) in the same field for many years, which is related to the secondary metabolites secreted by plants, among which vanillin is one of the factors causing CCOs of L. siceraria. This study investigated the effects of different concentrations of exogenous brassinolide (BR) on L. siceraria under CCOs.MethodsHigh-performance liquid chromatography (HPLC) was used to determine the contents of vanillin in rhizosphere soil of non-planted soil, 1-year-old, 2-year-old, and 3-year-old L. siceraria cultivation. This study investigated the effects of BR at concentrations of 0.05, 0.10, 0.20 and 0.40 mg/mL on L. siceraria under CCOs by applying 6.00 mg/mL vanillin to simulate CCOs.ResultsThe contents of vanillin in the rhizosphere soil of non-planted soil, 1-year-old, 2-year-old, and 3-year-old were 0.01, 0.03, 0.06 and 0.10 mg/g. The BR could effectively alleviate the stress imposed by vanillin and enhance the tolerance of L. siceraria to vanillin stress. When the concentration of BR was 0.20 mg/mL, the alleviation effect on vanillin stress was the most significant. Compared with the vanillin stress group, the plant height, the projected area of the root, number of tips, and total root length enhanced by 1.52, 4.21, 4.43, and 6.12 times. When the light intensity was 1200 lx, the transpiration rate and stomatal conductance increased by 68.57% and 48.00%. At the same time, the antioxidant enzyme activities had the best alleviation at 0.20 mg/mL.ConclusionThe vanillin significantly inhibited the growth of L. siceraria seedlings at elevated concentrations. Furthermore, its persistent accumulation in the soil via root exudation was identified as a contributing factor to CCOs. It was worth noting that 0.20 mg/mL BR could alleviate the damage caused by CCOs to L. siceraria seedlings.

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.

The application of 2,4-epibrassinolide (EBR) is considered an effective and environment friendly method to improve plant growth under heavy metal (HM) stress, which is crucial for crop productivity and environmental phytoremediation. This meta-analysis evaluated plant responses to exogenous EBR under HM stress by compiling data from 73 studies, including 2480 observations. Results showed that the most significant effects of exogenous EBR on plant growth and HM uptake parameters were observed on shoot/root length (47.9 %) and HM concentration in plant tissues (-32.9 %). EBR application enhanced photosynthesis and the mitigation of oxidative damage by significantly boosting antioxidant enzyme activity, non-enzymatic antioxidants, and metabolites. Exogenous EBR induced the largest percentage changes in plant growth and HM uptake under nickel stress, with an average increase of 57.5 % and a decline of 38.5 %, respectively. The greatest effects of exogenous EBR on plant growth and HM uptake parameters were observed in plants of the Cruciferae family, while the lowest effects were in the Gramineae family. In terms of EBR application characteristics, seed soaking with lower EBR concentrations (<= 1 nM) is recommended for crop production in HM-contaminated soils. These findings underscore the potential of exogenous EBR in achieving sustainable agriculture and environmental phytoremediation in HM-contaminated soils.

Purpose: Anthropogenic factors have become the dominant cause of environmental pollution particularly salinity in soils resulting in alternation in plant's physiological and biochemical responses. Salinity-induced stress deleteriously affects crop productivity and has damaged about 6 million hectares in Pakistan. Sodium fluoride (NaF) has emerged as a prominent source of salinity stress and its accumulation in crops has become a major concern worldwide. Seed priming has marked its position as a beneficial technique for salt stress attenuation in various crops. Methods: The current research work was intended to scrutinize the valuable aspect of seed priming with 28-homobrassinolide (HBR) on morphological and biochemical attributes of Pisum sativum L. (pea) plants under NaF stress. P. sativum seeds were subjected to seed priming with three different concentrations of HBR (1 mu M, 5 mu M, and 10 mu M L-1). Results: Sodium fluoride-induced toxicity exhibited a significant decline in the growth of pea plants. The results showed that NaF negatively affected total chlorophyll content (25%), stomatal conductance (28%), and rate of transpiration (46%) and photosynthetic rate (28%) as compared to Control. Nevertheless, seed priming with HBR2 enhanced carotenoid content (65%) and consequent improvement in shoot length (64%), and root's dry biomass (59%) of plants as compared to Control plants were ascertained. All three treatments improved the above-mentioned traits but a maximum increment was observed in response to 5 mu M L-1HBR treatment as compared to the Control. Furthermore, HBR2 improved the gas exchange parameters and proline content (74%) under stress conditions. Conclusions: Although, plants under saline stress demonstrated a decline in morpho-physiological attributes of pea plants but these deleterious effects of salinity were alleviated by HBR priming of the pea seeds.