Two Isozymes of a Novel Non-specific Phospholipase C Family, NPC4 and NPC5, Differentially Play Roles During Phosphate Starvation in Arabidopsis.

Abstract

Phosphate (Pi) is one of the most important growth-limiting nutrients. When plants suffer from phosphate limitation, overall phospholipid contents that correspond to 30% of total Pi storage is decreased and, conversely, contents of some non-phosphorus galactolipids such as digalactosyldiacylglycerol (DGDG) increase significantly. Although several studies reported that Pi starvation induces enzymes for galactolipid biosynthesis, the mechanisms for phospholipid degradation is yet unknown.
We identified a novel non-specific phospholipase C (NPC) family in Arabidopsis. Among them, NPC4 and NPC5 were both induced by Pi starvation but differentially localized. While NPC4 was responsible for the bulk NPC activity induced by Pi starvation, only npc5 showed decreased DGDG accumulation upon Pi deprivation. Thus, these isozymes are differentially play roles in the Pi starvation-inducible phospholipid degradation in vivo.