Brassinosteroids (BRs) are well-ascertained growth regulators that play prime roles in alleviation of a stress in plants. The current investigation determined the impact of epibrassinolide (EBR) applied as seed pretreatment on growth attributes, physiological attributes and antioxidant potential of tomato plants grown under Cr(VI) metal stress. Applications of EBR were found to be effective in improving growth of control as well as Cr-stressed plants in terms of lengths of shoot and root and their dry weights. Of the physiological parameters, stomatal conductance was the most sensitive to chromium exposure exhibiting 72.15% decline, while photosynthetic rate decreased to 33.16%. Chromium stress led to decline in non-enzymatic antioxidants like GSH by 41.85% and in total flavonoid by 69.48%. Application of EBR modulated more significantly the titres of antioxidants (glutathione, ascorbic acid, total flavonoids and activities of antioxidant enzymes (ascorbate peroxidase, catalase, superoxide dismutase, glutathione- S -transferase and glutathione reductase) as well as proline and glycine betaine in Cr-stressed plants compared to those in plants receiving no supply of EB. Diminution of Cr stress by EBR was also maintained by higher values of stress indices, such as flavonoids, photosynthetic pigments and reduction in malondialdehyde and H 2 O 2 levels in the Cr-treated plants than those in the controls. Restricted production of ROS and improved quenching of ROS were also recorded due to EBR application under Cr stress. At the same time, insignificant reduction in uptake of Cr was noticed due to application of EBR in leaves compared to that in roots of Cr-stressed plants. Overall, our results reveal that application of EBR can effectively act as a growth stimulant in plants subjected to Cr stress. Therefore, it can be conjectured that the interaction of 24-epibrassinolide remodulates the physiological, metabolic and defence system of the tomato thriving under chromium stress by equilibrating the Cr accumulation.

中文翻译：

---

24-Epibrassinolide 减轻番茄植物中 Cr(VI) 毒性的有害影响：对生长、生理生化特性、抗氧化活性和抗坏血酸-谷胱甘肽和乙二醛酶循环的调节的洞察

油菜素类固醇 (BRs) 是公认的生长调节剂，在减轻植物压力方面发挥主要作用。目前的研究确定了表油菜素内酯 (EBR) 作为种子预处理对在 Cr(VI) 金属胁迫下生长的番茄植株的生长属性、生理属性和抗氧化潜力的影响。发现 EBR 的应用在提高对照植物和 Cr 胁迫植物的芽和根长度及其干重方面是有效的。在生理参数中，气孔导度对铬暴露最敏感，下降 72.15%，而光合速率下降至 33.16%。铬胁迫导致谷胱甘肽等非酶抗氧化剂减少 41.85%，总黄酮减少 69.48%。与 Cr 胁迫植物的根相比，由于在叶子中应用 EBR，注意到对 Cr 的吸收显着减少。总体而言，我们的结果表明，在受到铬胁迫的植物中，EBR 的应用可以有效地充当生长刺激剂。因此，可以推测，24-表布拉斯内酯的相互作用通过平衡Cr积累来重新调节在铬胁迫下茁壮成长的番茄的生理、代谢和防御系统。