Abstract：
VIP1, an Arabidopsis thaliana basic leucine zipper transcription factor, and its close homologs are imported from the cytoplasm to the nucleus when cells are exposed to mechanical stress. They bind to AGCTG (G/T) and regulate mechanical stress responses in roots. However, their role in leaves is unclear. To clarify this, mutant lines (QM1 and QM2) that lack the functions of VIP1 and its close homologs (bZIP29, bZIP30 and PosF21) were generated. Brushing more severely damaged QM1 and QM2 leaves than wild-type leaves. Genes regulating stress responses and cell wall properties were downregulated in brushed QM2 leaves and upregulated in brushed VIP1-GFP-overexpressing (VIP1-GFPox) leaves compared to wild-type leaves in a transcriptome analysis. The VIP1-binding sequence AGCTG (G/T) was enriched in the promoters of genes downregulated in brushed QM2 leaves compared to wild-type leaves and in those upregulated in brushed VIP1-GFPox leaves. Calmodulin-binding transcription activators (CAMTAs) are known regulators of mechanical stress responses, and the CAMTA-binding sequence CGCGT was enriched in the promoters of genes upregulated in the brushed QM2 leaves and in those downregulated in the brushed VIP1-GFPox leaves. These findings suggest that VIP1 and its homologs upregulate genes via AGCTG (G/T) and influence CAMTA-dependent gene expression to enhance mechanical stress tolerance in leaves.
摘要：
拟南芥碱性亮氨酸拉链转录因子VIP1,当细胞受到机械应力时，其紧密同源物从细胞质输入到细胞核。它们结合AGCTG(G/T)并调节根中的机械应激反应。然而,它们在树叶中的作用尚不清楚。为了澄清这一点，产生了缺乏VIP1及其紧密同源物（bZIP29，bZIP30和PosF21）功能的突变系（QM1和QM2）。刷洗对QM1和QM2叶片的损害比野生型叶片严重。在转录组分析中，与野生型叶片相比，调节应激反应和细胞壁特性的基因在刷过的QM2叶片中下调，而在刷过的VIP1-GFP过表达（VIP1-GFPox）叶片中上调。与野生型叶相比，VIP1结合序列AGCTG（G/T）富集在拉丝QM2叶中下调的基因启动子中，以及在拉丝VIP1-GFPox叶中上调的基因启动子中。钙调蛋白结合转录激活因子（CAMTA）是机械应激反应的已知调节剂，CAMTA结合序列CGCGCGT富集在拉丝QM2叶片中上调的基因启动子和拉丝VIP1-GFPox叶片中下调的基因启动子中。这些发现表明VIP1及其同源物通过AGCTG（G/T）上调基因，并影响CAMTA依赖性基因表达以增强叶片的机械胁迫耐受性。
