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

Magnesium (Mg2+) is a macronutrient involved in essential cellular processes. Its deficiency or excess is a stress factor for plants, seriously affecting their growth and development and therefore, its accurate regulation is essential. Recently, we discovered that phospholipase D alpha 1 (PLD alpha 1) activity is vital in the stress response to high-magnesium conditions in Arabidopsis roots. This study shows that PLD alpha 1 acts as a negative regulator of high-Mg2+-induced leaf senescence in Arabidopsis. The level of phosphatidic acid produced by PLD alpha 1 and the amount of PLD alpha 1 in the leaves increase in plants treated with high Mg2+. A knockout mutant of PLD alpha 1 (pld alpha 1-1), exhibits premature leaf senescence under high-Mg2+ conditions. In pld alpha 1-1 plants, higher accumulation of abscisic and jasmonic acid (JA) and impaired magnesium, potassium and phosphate homeostasis were observed under high-Mg2+ conditions. High Mg2+ also led to an increase of starch and proline content in Arabidopsis plants. While the starch content was higher in pld alpha 1-1 plants, proline content was significantly lower in pld alpha 1-1 compared with wild type plants. Our results show that PLD alpha 1 is essential for Arabidopsis plants to cope with the pleiotropic effects of high-Mg2+ stress and delay the leaf senescence.

Automated summary

The study found that PLD alpha 1 plays a crucial role in Arabidopsis plants' response to high-magnesium stress, delaying leaf senescence. Knockout mutants of PLD alpha 1 exhibited premature leaf aging and disrupted homeostasis of essential nutrients such as magnesium, potassium, and phosphate under high-Mg2+ conditions. Additionally, high Mg2+ levels led to increased starch and proline content in Arabidopsis plants, with significantly different levels observed in the PLD alpha 1 mutant compared to wild type plants.