The role of brassinosteroids (BRs) in enabling plants to respond effectively to adverse conditions is well known, though the precise mechanism of action that helps plants cope with arsenic (As) toxicity is still difficult to interpret. Therefore we tested the effect of brassinolide (BL) spray (0, 0.5, and 1 mg · L−1) on As (0, and 10 mg · L−1) stressed tomato defense responses As stress led to the induction of oxidative stress, impaired chlorophyll and nitrogen metabolism, and Fe uptake, in conjunction with a reduction in plant growth and biomass. BL spray, on the contrary, protected the photosynthetic system and helped plants grow better under As stress. This was achieved by controlling the metabolism of chlorophyll and proline and lowering the amounts of methylglyoxal and H2O2 through glyoxalase I and II and antioxidant enzymes. BL decreased arsenic accumulation by directing As sequestration towards vacuoles and increased Fe amount in the leaves and roots by regulating the expression of As (Lsi1 and Lsi2) and Fe (IRT1, IRT2, NRAMP1, and NRAMP3) transporters in As-stressed tomatoes. Furthermore, BL boosted adaptability against As phytotoxicity, while reducing the damaging impacts on photosynthesis, nitrogen metabolism, sulfur asimilation, and Fe absorption. These results offer a solid framework for the development of exogenous BRs-based breeding strategies for safer agricultural development.

中文翻译：

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芸苔素内酯改善番茄中砷的有害影响：深入了解铁和砷的吸收、抗氧化能力、氮和硫的同化


油菜素类固醇 （BRs） 在使植物能够有效应对不利条件方面的作用是众所周知的，尽管帮助植物应对砷 （As） 毒性的确切作用机制仍然难以解释。因此，我们测试了油菜素内酯 （BL） 喷雾剂（0、0.5 和 1 mg ·L−1） 对 As（0 和 10 mg ·L−1） 应激番茄防御反应 As 应激导致氧化应激的诱导，叶绿素和氮代谢受损，以及铁的吸收受损，同时植物生长和生物量减少。相反，BL 喷雾保护了光合系统，帮助植物在 As 胁迫下生长得更好。这是通过控制叶绿素和脯氨酸的代谢以及通过乙二醛酶 I 和 II 以及抗氧化酶降低甲基乙二醛和 H 2 O 2 的含量来实现的。BL 通过调节 As （Lsi1 和 Lsi2） 和 Fe （IRT1、IRT2、NRAMP1 和 NRAMP3） 转运蛋白的表达，通过调节 As 胁迫西红柿中液泡的螯合来减少砷积累，并增加叶片和根中 Fe 的含量。此外，BL 提高了对 As 植物毒性的适应性，同时减少了对光合作用、氮代谢、硫同化和 Fe 吸收的破坏性影响。这些结果为开发基于外源 BRs 的育种策略以实现更安全的农业发展提供了坚实的框架。