Brassinazole-resistant (BZR) transcription factors have important roles in the brassinosteroid (BR) signalling pathway and are widely involved in plant growth and abiotic stress processes. However, there are few studies on the functions and regulatory mechanisms of BZR TFs in birch. In this study, 5 BZR genes were identified from birch. The qRT-PCR results showed that the expression levels of most BpBZRs were significantly downregulated and/or upregulated in at least one organ following NaCl and PEG stress or ABA, GA3 and JA treatments. In particular, BpBZR1 expression was changed in all three organs after exposure to NaCl stress at all time points, indicating that this gene may be involved in salt stress. The BpBZR1 transcription factor was shown to have transcriptional activation activity in a yeast two-hybrid assay. Through a transient transformation system, we found that overexpression of BpBZR1 in birch resulted in lower H2O2 and MDA accumulation, higher SOD and POD activities and maintained a higher photosynthetic intensity and a lower chlorophyll degradation rate than those of the control plants under salt stress. These results preliminarily showed that overexpression of the BpBZR1 gene increased the tolerance of birch to salt stress.

中文翻译：

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白桦BpBZR基因对非生物胁迫和激素处理的响应。

耐油菜籽素（BZR）转录因子在油菜素类固醇（BR）信号传导途径中具有重要作用，并广泛参与植物生长和非生物胁迫过程。但是，关于桦木中BZR TF的功能和调控机制的研究很少。在这项研究中，从桦树中鉴定出5个BZR基因。qRT-PCR结果表明，在NaCl和PEG胁迫或ABA，GA3和JA处理后，至少一个器官中大多数BpBZRs的表达水平显着下调和/或上调。特别是，在所有时间点都暴露于NaCl胁迫后，所有三个器官的BpBZR1表达均发生了变化，表明该基因可能与盐胁迫有关。BpBZR1转录因子在酵母双杂交检测中显示具有转录激活活性。通过瞬时转化系统，我们发现在盐胁迫下，桦木中BpBZR1的过表达导致了H2O2和MDA的积累，较高的SOD和POD活性，并保持了较高的光合强度和较低的叶绿素降解率。这些结果初步表明，BpBZR1基因的过表达增加了桦树对盐胁迫的耐受性。