Kapri, R., Department of Citriculture, Institute of Horticulture, Agricultural Research Organization, P.O. Box 6, 50250 Bet Dagan, Israel
Dahan, E., Department of Citriculture, Institute of Horticulture, Agricultural Research Organization, P.O. Box 6, 50250 Bet Dagan, Israel
Sadka, A., Department of Citriculture, Institute of Horticulture, Agricultural Research Organization, P.O. Box 6, 50250 Bet Dagan, Israel
Zehavi, U., Kennedy-Leigh Centre for Horticultural Research, Faculty of Agriculture, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, 76100 Rehovot, Israel
Goren, R., Kennedy-Leigh Centre for Horticultural Research, Faculty of Agriculture, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, 76100 Rehovot, Israel

As part of a study of sugar metabolism in citrus fruit, a full-length cDNA encoding for the two subunits of the PPi-dependent phosphofructokinase (PFPa; PFPβ) were cloned from grapefruit juice sac cells. The clones share over 85% homology with PFPs of other plants. Expression of the genes was studied during orange fruit development. Both genes exhibit the highest level of expression in the flower. A different pattern is observed in fruits: PFPα is barely detected in young fruits of 20-30 mm, and is induced in 35-40 mm fruits, whereas PFPβ is constitutively expressed in fruits of 20-40 mm. These results suggest that the ratio of PFPα/PFPβ changes at various stages of fruit development.