Abstract
Phospholipase D (PLD) is the enzyme that hydrolyzes phosphatidylcholine and generates phosphatidic acid and choline. The Arabidopsis genome encodes 12 PLDs which are classified into 10 plant-specific PLDs and 2 eukaryote-general PLDs by their domain structures.
The promoter activity of PLDz2 is detected in upper region of root-tips and pollen grains, while that of PLDz1 is strongly detected in most of the tissues. Furthermore, expression of PLDz2 is increased under phosphate-starved condition. Mutations in 4 of the PHR1 recognition site upstream of PLDz2 gene reduced responsibility for phosphate starvation on PLDz2 expression. Additionally, PLDz2 expression remained unchanged under phosphate-starved condition in phr1 mutant. These results indicate that the response of PLDz2 to phosphate starvation is mediated through PHR1.
Interestingly PLDz2 mutants do not show phenotypic changes under normal or phosphate-starved conditions. Hypothesis on the role of PLDz2 to retrieve phosphate from plasma membrane under phosphate-starved condition will be discussed.
