The occurrence of phosphoenolpyruvate carboxykinase (PEPCK) and enzymes related to photosynthesis and organic acid/nitrogen metabolism in apricot flowers (Prunus armeniaca L.)

This study determined the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) and some enzymes involved in photosynthesis and organic acid/nitrogen metabolism in the different parts of apricot flowers and some other tissues of apricot. Both PEPCK protein and activity were detected in the petal, carpel, stamen filament and in the flesh of both unripe and ripe fruits, but not in the sepal or mature leaf. Both PEPCK polypeptide and activity were most abundant in the flesh of ripe fruits. In floral tissues the photosynthetic enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and putative plastidic glutamine synthase and plastidic aldolase were most abundant in the sepal in which PEPCK was not detected. The potential functions of PEPCK in the different tissues of apricot are discussed. This study highlights the potential importance of gluconeogenesis in floral metabolism.