Immunohistochemical localization of phospholipase D in strawberry (Fragaria ananassa Duch.) fruits

Phospholipase D, the key enzyme involved in membrane phospholipid catabolism, was localized in strawberry (Fragaria ananassa Duch.) fruits during development using immunohistochemical techniques. Typical structural features such as the nucleus, cell wall, plasma membrane, mitochondria and vacuole were noticeable in cells of young strawberry fruits. Cytoplasmic structural features were less pronounced in fully grown and turning red fruits, except cell wall, which was considerably enlarged. Also, extensive microvesiculation from the plasma membrane was noticeable in ripening fruits. The number of visible gold particles indicative of phospholipase D increased during development. Phospholipase D was found to be associated with membranous structures and vacuole. Interestingly, gold-particles could also be observed in the cell wall space in ripening fruits suggesting that cytosolic contents may have leaked into the cell wall space as a result of membrane deterioration and loss of compartmentalization. The role of phospholipase D during development and ripening of strawberry, a non-climacteric fruit, is discussed.