College of Horticulture, Shanxi Agricultural University, Taigu, 030801, P. R. China.
Shanxi Key Laboratory of Germplasm Resources Innovation and Utilization of Vegetable and Flower, Taiyuan, 030031, P. R. China.
Plant J. 2024 Nov;120(4):1536-1551. doi: 10.1111/tpj.17065. Epub 2024 Oct 8.
Cytokinin is central to coordinating plant adaptation to environmental stresses. Here, we first demonstrated the involvement of cytokinin in Arabidopsis responses to arsenite [As(III)] stress. As(III) treatment reduced cytokinin contents, while cytokinin treatment repressed further primary root growth in Arabidopsis plants under As(III) stress. Subsequently, we revealed that the cytokinin signaling members ARR1 and ARR12, the type-B ARABIDOPSIS RESPONSE REGULATORs, participate in cytokinin signaling-mediated As(III) responses in plants as negative regulators. A comprehensive transcriptome analysis of the arr1 and arr12 single and arr1,12 double mutants was then performed to decipher the cytokinin signaling-mediated mechanisms underlying plant As(III) stress adaptation. Results revealed important roles for ARR1 and ARR12 in ion transport, nutrient responses, and secondary metabolite accumulation. Furthermore, using hierarchical clustering and regulatory network analyses, we identified two NODULIN 26-LIKE INTRINSIC PROTEIN (NIP)-encoding genes, NIP1;1 and NIP6;1, potentially involved in ARR1/12-mediated As(III) uptake and transport in Arabidopsis. By analyzing various combinations of arr and nip mutants, including high-order triple and quadruple mutants, we demonstrated that ARR1 and ARR12 redundantly function as negative regulators of As(III) tolerance by acting upstream of NIP1;1 and NIP6;1 to modulate their function in arsenic accumulation. ChIP-qPCR, EMSA, and transient dual-LUC reporter assays revealed that ARR1 and ARR12 transcriptionally activate the expression of NIP1;1 and NIP6;1 by directly binding to their promoters and upregulating their expression, leading to increased arsenic accumulation under As(III) stress. These findings collectively provide insights into cytokinin signaling-mediated plant adaptation to excessive As(III), contributing to the development of crops with low arsenic accumulation.
细胞分裂素在协调植物适应环境胁迫方面起着核心作用。在这里，我们首先证明了细胞分裂素参与了拟南芥对亚砷酸盐（As(III)）胁迫的反应。As(III)处理降低了细胞分裂素的含量，而细胞分裂素处理抑制了拟南芥植物在 As(III)胁迫下的主根进一步生长。随后，我们揭示了细胞分裂素信号成员 ARR1 和 ARR12，即 B 型拟南芥响应调节剂，作为负调节剂参与植物中细胞分裂素信号介导的 As(III)反应。然后对 arr1 和 arr12 单突变体和 arr1,12 双突变体进行了全面的转录组分析，以破译植物适应 As(III)胁迫的细胞分裂素信号介导机制。结果表明，ARR1 和 ARR12 在离子运输、养分响应和次生代谢物积累中发挥了重要作用。此外，通过层次聚类和调控网络分析，我们鉴定出两个可能参与 ARR1/12 介导的拟南芥 As(III)摄取和转运的 NODULIN 26-LIKE INTRINSIC PROTEIN (NIP)-编码基因，NIP1;1 和 NIP6;1。通过分析包括高阶三重和四重突变体在内的各种 arr 和 nip 突变体的组合，我们证明了 ARR1 和 ARR12 通过作为 NIP1;1 和 NIP6;1 的上游负调节剂来冗余地发挥作用，调节它们在砷积累中的功能，从而提高对 As(III)的耐受性。ChIP-qPCR、EMSA 和瞬时双-LUC 报告基因测定显示，ARR1 和 ARR12 通过直接结合其启动子并上调其表达，转录激活 NIP1;1 和 NIP6;1 的表达，导致在 As(III)胁迫下砷积累增加。这些发现共同深入了解了细胞分裂素信号介导的植物对过量 As(III)的适应，为开发低砷积累作物提供了依据。
