Brassinolide (BR) enhances the efficiency of photosynthetic machinery through the activation of metabolic pathways, photochemistry, and ribulose activity. However, the potential transcriptional mechanism mediating these processes through BR signaling still needed to be elucidated. In this study, we found the concealed BR-signaling mediated effects on tomato leaf morpho-physiological and biochemical traits, including chlorophyll accumulation, and photosynthetic efficiency. Under controlled conditions, the altered brassinolide sensitivity1 (abs1) mutant showed decreased leaf area and biomass associated with substantially reduced vascularization and epidermal cell size. abs1 mutant displayed significantly decreased chlorophyll accumulation and suppression in photosynthetic machinery components like photochemical quenching, electron transport rate, the maximal quantum yield of PSII photochemistry, and net photosynthetic rate. Whereas an increase in minimal fluorescence yield and non-photochemical quenching, suggests that abs1 mutant leaf has weakened abilities to harvest and transfer light energy. Moreover, the transcriptome analysis revealed differentially expressed genes involved in the chlorophyll biosynthesis and photosystem (PSI and PSII) reaction center. The abs1 mutant depicted the decreased expression level of genes encoding light-harvesting chlorophyll a / b binding proteins and photosystem II binding protein A required for the reaction center of the PSII complex. In addition, hormonal profiling of the abs1 mutant indicates the complexity of the BR and other phytohormones interactions. Our findings concluded that the BR signaling reduction transcriptionally impairs chlorophyll synthesis, quantum photon harvesting, and light energy transfer, leading to a decrease in photosynthetic capacity.

中文翻译：

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改变油菜素内酯敏感性 1 转录抑制番茄叶绿素合成和光合作用能力

芸苔素内酯 (BR) 通过激活代谢途径、光化学和核酮糖活性来提高光合机制的效率。然而，仍然需要阐明通过 BR 信号传导介导这些过程的潜在转录机制。在这项研究中，我们发现隐藏的 BR 信号介导对番茄叶片形态生理和生化性状的影响，包括叶绿素积累和光合效率。在受控条件下，改变的芸苔素内酯敏感性1（abs1）突变体显示出与血管化和表皮细胞大小显着减少相关的叶面积和生物量减少。abs1 突变体在光合机械组件（如光化学淬灭、电子传递速率、PSII 光化学的最大量子产率和净光合速​​率。而最小荧光产量和非光化学猝灭的增加，表明 abs1 突变体叶片收获和转移光能的能力减弱。此外，转录组分析揭示了参与叶绿素生物合成和光系统（PSI 和 PSII）反应中心的差异表达基因。abs1 突变体描述了编码捕光叶绿素 a/b 结合蛋白和光系统 II 结合蛋白 A 的基因表达水平降低，这些蛋白是 PSII 复合物的反应中心所需的。此外，abs1 突变体的激素分析表明 BR 和其他植物激素相互作用的复杂性。