State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, China.
State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, China.
Plant Physiol Biochem. 2020 Jun;151:157-165. doi: 10.1016/j.plaphy.2020.03.001. Epub 2020 Mar 8.
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, GA 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 HO 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.
油菜素内酯（BR）信号通路中的 BR 不敏感转录因子（BZR）在植物生长和非生物胁迫过程中发挥着重要作用。然而，关于 BZR 转录因子在桦树中的功能和调控机制的研究较少。本研究从桦树中鉴定出 5 个 BZR 基因。qRT-PCR 结果表明，在 NaCl 和 PEG 胁迫或 ABA、GA 和 JA 处理后，大多数 BpBZRs 的表达水平在至少一种器官中显著下调和/或上调。特别是，BpBZR1 在 NaCl 胁迫下所有三个器官的表达均发生变化，表明该基因可能参与盐胁迫。酵母双杂交试验表明，BpBZR1 转录因子具有转录激活活性。通过瞬时转化系统，我们发现与对照植株相比，在盐胁迫下，桦树中 BpBZR1 的过表达导致 HO 和 MDA 积累减少，SOD 和 POD 活性增加，并且保持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 基因的过表达提高了桦树对盐胁迫的耐受性。
