Intracellular levels of Mg²⁺ are tightly regulated, as Mg²⁺ deficiency or excess affects normal plant growth and development. In Arabidopsis, we determined that phospholipase Dα1 (PLDα1) is involved in the stress response to high‐magnesium conditions. The T‐DNA insertion mutant pldα1 is hypersensitive to increased concentrations of magnesium, exhibiting reduced primary root length and fresh weight. PLDα1 activity increases rapidly after high‐Mg²⁺ treatment, and this increase was found to be dose dependent. Two lines harbouring mutations in the HKD motif, which is essential for PLDα1 activity, displayed the same high‐Mg²⁺ hypersensitivity of pldα1 plants. Moreover, we show that high concentrations of Mg²⁺ disrupt K⁺ homeostasis, and that transcription of K⁺ homeostasis‐related genes CIPK9 and HAK5 is impaired in pldα1. Additionally, we found that the akt1, hak5 double mutant is hypersensitive to high‐Mg²⁺. We conclude that in Arabidopsis, the enzyme activity of PLDα1 is vital in the response to high‐Mg²⁺ conditions, and that PLDα1 mediates this response partially through regulation of K⁺ homeostasis.

中文翻译：

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磷脂酶Dα1通过调节K +稳态来介导高Mg2 +应激反应。

Mg ^2+的细胞内水平受到严格调节，因为Mg ²⁺缺乏或过量会影响正常植物的生长发育。在拟南芥中，我们确定磷脂酶Dα1（PLDα1）参与了对高镁条件的胁迫响应。T‐DNA插入突变体pldα1对增加的镁浓度非常敏感，表现出减少的初生根长度和鲜重。高Mg ²⁺处理后PLDα1活性迅速增加，并且发现这种增加是剂量依赖性的。HKD母题中有两个突变，这对PLDα1活性至关重要，它们显示出与pldα1相同的高Mg ²⁺超敏性植物。此外，我们发现，高浓度的Mg ²⁺会破坏K ⁺稳态，并且pldα1中会损害K ⁺稳态相关基因CIPK9和HAK5的转录。此外，我们发现akt1，hak5双突变体对高Mg ²⁺过敏。我们得出结论，在拟南芥中，PLDα1的酶活性在对高Mg ²⁺条件的反应中至关重要，并且PLDα1部分通过调节K ⁺稳态来介导此反应。