Brassinosteroids (BRs) are a class of plant-specific steroid hormones that play key roles in plant physiology and that actively participate in the regulation of plant responses to stress. Thus, these compounds are also considered biostimulants that could be applied to crops to improve plant performance and induce abiotic stress tolerance. In this study, with a combined physiological and molecular approach, new insights into the effects of 24-epibrassinolide (EBL), a synthetic BR, on hydroponically grown maize seedlings were gained. To this aim, a preliminary assessment of the effect of different EBL concentrations and treatment times on root elongation was evaluated to determine the concentration to use in subsequent experiments. Treatment with 1 nM EBL and an exposure time of 48 h were selected to better assess the effects of this molecule on shoot growth and the root gravitropic response. Subsequently, an untargeted RNA-Seq-based approach was applied to obtain an overview of the transcriptomic regulation occurring in the roots, shoots and leaves upon exogenous brassinosteroid application. Our outcomes highlight the substantial influence exerted by this molecule on the growth and root gravitropic response of maize seedlings. Moreover, new insights into the BR response and BR signalling in plants were gained by performing the functional characterization of differentially expressed genes via Gene Ontology (GO) and pathway analyses. Overall, this study provides useful information that could help future agricultural applications of these substances.

中文翻译：

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油菜素类固醇的应用通过调节根、芽和叶中的基因表达影响玉米的生长和向地性反应

油菜素类固醇 (BRs) 是一类植物特异性类固醇激素，在植物生理学中起关键作用，并积极参与植物对胁迫反应的调节。因此，这些化合物也被认为是可应用于作物以提高植物性能和诱导非生物胁迫耐受性的生物刺激剂。在这项研究中，结合生理学和分子学方法，获得了对合成 BR 24-表油菜素内酯 (EBL) 对水培玉米幼苗影响的新见解。为此，初步评估了不同 EBL 浓度和处理时间对根伸长的影响，以确定后续实验中使用的浓度。选择用 1 nM EBL 处理和 48 小时的暴露时间以更好地评估该分子对枝条生长和根向重力反应的影响。随后，应用基于非靶向 RNA-Seq 的方法来概述外源油菜素类固醇应用后根、芽和叶中发生的转录组调控。我们的结果强调了这种分子对玉米幼苗的生长和根向重力反应产生的重大影响。此外，通过基因本体论 (GO) 和通路分析对差异表达基因进行功能表征，获得了对植物中 BR 响应和 BR 信号传导的新见解。总的来说，这项研究提供了有用的信息，可以帮助这些物质的未来农业应用。