Phospholipase Dα1 acts as a negative regulator of high Mg2+-induced leaf senescence in Arabidopsis

Abstract

Magnesium 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 D1 (PLD1) activity is vital in the stress response to high-magnesium conditions in Arabidopsis roots. This study shows that PLD1 acts as a negative regulator of high-Mg2+-induced leaf senescence in Arabidopsis. The level of phosphatidic acid produced by PLD1 and the amount of PLD1 in the leaves increase in plants treated with high Mg2+. A knockout mutant of PLD1 (plda1-1), exhibits premature leaf senescence under high-Mg2+ conditions. In pld1-1 plants, higher accumulation of abscisic and jasmonic acid 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 plda1-1 plants, proline content was significantly lower in plda1-1 compared with WT. Our results show that PLD1 is essential for Arabidopsis plants to cope with the pleiotropic effects of high-Mg2+ stress and delay the leaf senescence.