Abstract
Phosphorus is essential for plant viability. Phosphate-starved plants trigger membrane lipid remodeling to replace membrane phospholipids by non-phosphorus galactolipids presumably to acquire scarce phosphate source. Phosphoethanolamine/phosphocholine phosphatase 1 (PECP1) and phosphate starvation-induced gene 2 (PS2) belong to an emerging class of phosphatase induced by phosphate starvation and dephosphorylates phosphocholine and phosphoethanolamine (PEtn) in vivo. However, detailed spatiotemporal expression pattern as well as subcellular localization has not been investigated yet. Here, by constructing transgenic plants harboring functional translational promoter–reporter fusion system, we showed the expression pattern of PECP1 and PS2 in different tissues and in response to phosphate starvation. Besides, the Venus fluorescent reporter revealed that both are localized at the ER. Characterization of transgenic plants that overexpress PECP1 or PS2 showed that their activity toward PEtn may be different in vivo. We suggest that PECP1 and PS2 are ER-localized phosphatases that show similar expression pattern yet have a distinct substrate specificity in vivo.
Highlights
Phosphorus is an essential nutrient for plant growth and development
Under phosphate-starved condition, a slight but significant reduction was detected (Figure 5A), which indicates that Phosphoethanolamine/phosphocholine phosphatase 1 (PECP1) and phosphate starvation-induced gene 2 (PS2) may be involved in the dephosphorylation of PEtn in vivo under phosphate starvation
Membrane lipid remodeling is an important metabolic response for plants to cope with phosphate starvation (Nakamura, 2013)
Summary
Phosphorus is an essential nutrient for plant growth and development. Due to limited availability in many soils, metabolic change toward utilization of plant internal phosphate reserve is an important response to circumvent phosphate starvation. A metabolic conversion termed the membrane lipid remodeling (Nakamura, 2013) occurs that replaces phosphate-containing polar head group of phospholipids with non-phosphorus galactose group, thereby converting the membrane lipid content from phospholipids to galactolipids presumably to cope with phosphate starvation (Figure 1A). Gene knockout study that impedes the conversion process suggests that this metabolic remodeling is important in plant phosphate starvation tolerance (Nakamura et al, 2009), there is lack of evidence as to whether polar head group-derived phosphate is utilized as a phosphate source. This is because the identity and function of phosphatase(s) that dephosphorylates the polar head group has remained enigmatic in plants
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