Phospholipase Dα1 mediates the high‐Mg²⁺ stress response partially through regulation of K⁺ homeostasis

Abstract

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.

Phospholipase Dα1 Acts as a Negative Regulator of High Mg2+-Induced Leaf Senescence in Arabidopsis

“…Knockout line pldα1-1 (SALK_067533) was obtained from the NASC. Complemented lines pldα1-1 Com1 and pldα1-1 Com2 were described previously ( Kocourková et al, 2020 ).…”

“…Plates were kept in a growth chamber at 22°C during the day, 21°C at night, under long day (16h of light) conditions at 100μmolm −2 s −1 of light. Hydroponic plant cultivation was described in Kocourková et al (2020) . Twenty-four-day-old hydroponically cultivated plants were treated with either ½ Hoagland’s solution (control) or ½ Hoagland’s solution with 15mM MgSO 4 added.…”

“…Western blot analysis was performed as described previously ( Kocourková et al, 2020 ) with minor changes. Protein extracts were prepared as described above for TLC analysis.…”

Physiological and genetic analysis of tomato from two cultivars differing in potassium deficiency resistance

“…The accumulation of Ca 2+ and Mg 2+ has been reported to be associated with LK response (Behera et al 2016;Kocourková et al 2020;Dong et al 2021), and we measured the content of Ca 2+ and Mg 2+ in both JZ18 and JZ34 plants after LK treatment. The content of Ca 2+ and Mg 2+ were higher in the root of JZ34 than JZ18,while there were no significant difference in the shoots (Fig.…”

“…By contrast, in root and shoot tissues, the JZ34 showed lower Na + content than the JZ18 plants, which caused a higher Na + /K + ratio in JZ18 plants after LK stress. Especially, after LK treatment for 7 days in the roots, these Na + /K + ratio existed a significant difference between JZ34 and JZ18 plants, showing that the damage of ion homeostasis becomes more serious as the treatment time of LK stress increases in the roots of JZ18 plants.Recent research found that high concentrations of Mg 2+ disrupt K + homeostasis, and that transcription of K + homeostasis-related genes CIPK9 and HAK5 is changed to limit the elongation of root length (Kocourková et al 2020)…”