Brassinosteroids (BRs) play critical roles in plant growth and development, as well as in responses to abiotic stresses. The BRASSINAZOLE RESISTANT 1 (BZR1) and BRI1-EMS-SUPPRESSOR 1 (BES1) families of transcription factors have been elucidated largely in Arabidopsis and rice but not in other plant species. Here, we studied the functional characterization of a tomato (Solanum lycopersicum) BZR homolog gene, SlBZR1, in BR-regulated plant growth and tolerance to salt stress. SlBZR1 was highly expressed in the flowers and developing fruits of tomato. Both SlBZR1 and SlBZR1D (proline to leucine mutation at the 239th amino acid of SlBZR1) were transcriptional repressors and localized in the nucleus. SlBZR1 or SlBZR1D could interact with SlMYB30, SlMYBL2, SlPIF4, SlHAT1, SlIWS1 and SlREF6 in tomato. Overexpression of SlBZR1D enhanced the BR response and improved tolerance to salt stress in Arabidopsis, consistent with the phenotype of the Arabidopsis bes1-D mutant. Moreover, SlBZR1D-overexpressing tomato lines showed a short plant height, smaller and curly leaves, and delayed flowering. Additionally, SlBZR1D positively regulated salt tolerance in tomato and upregulated the expression of multiple stress-related genes. Our study provides new insights for understanding the function and mechanism of BZR transcription factors in BR-regulated plant growth and abiotic stress responses.

中文翻译：

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番茄 BZR/BES 转录因子 SlBZR1 正调控番茄和拟南芥中的 BR 信号传导和盐胁迫耐受性

油菜素类固醇 (BRs) 在植物生长和发育以及对非生物胁迫的响应中起着关键作用。BRASSINAZOLE RESISTANT 1 (BZR1) 和 BRI1-EMS-SUPPRESSOR 1 (BES1) 转录因子家族主要在拟南芥和水稻中阐明，但在其他植物物种中没有阐明。在这里，我们研究了番茄 (Solanum lycopersicum) BZR 同源基因 SlBZR1 在 BR 调节的植物生长和盐胁迫耐受性中的功能特征。SlBZR1 在番茄的花和发育果实中高度表达。SlBZR1 和 SlBZR1D（在 SlBZR1 的第 239 个氨基酸处脯氨酸到亮氨酸突变）都是转录抑制因子并定位于细胞核中。SlBZR1 或 SlBZR1D 可以与番茄中的 SlMYB30、SlMYBL2、SlPIF4、SlHAT1、SlIWS1 和 SlREF6 相互作用。SlBZR1D 的过表达增强了 BR 响应并提高了拟南芥对盐胁迫的耐受性，这与拟南芥 bes1-D 突变体的表型一致。此外，过表达 SlBZR1D 的番茄品系表现出矮小的株高、较小且卷曲的叶子和延迟开花。此外，SlBZR1D 正调节番茄的耐盐性并上调多个胁迫相关基因的表达。我们的研究为理解 BZR 转录因子在 BR 调节的植物生长和非生物胁迫响应中的功能和机制提供了新的见解。SlBZR1D 正调节番茄的耐盐性并上调多个胁迫相关基因的表达。我们的研究为理解 BZR 转录因子在 BR 调节的植物生长和非生物胁迫响应中的功能和机制提供了新的见解。SlBZR1D 正调节番茄的耐盐性并上调多个胁迫相关基因的表达。我们的研究为理解 BZR 转录因子在 BR 调节的植物生长和非生物胁迫响应中的功能和机制提供了新的见解。