Isolation and Characterization of Chalcone Synthase and Chalcone Isomerase cDNAs from Grapefruit (Citrus paradisi Macf.)

in HortScience
View More View Less
  • 1 Horticultural Sciences Dept., Institute of Food and Agricultural Sciences, Univ. of Florida, Gainesville, FL 32611

Many Citrus species accumulate large amounts of flavonoids, specifically flavanone glycosides, that impart an intensely bitter flavor to the fruit. In grapefruit, this bitterness decreases the acceptability of fresh fruit and juice; in other species, these compounds entirely prevent fruit consumption. No physiological purpose for the accumulation of these compounds has been determined; they do not function in color production or, as far as is known, in defense responses. As has been found in other plants, the accumulation of specific flavonoids in citrus appears to be under genetic control, but no definitive genetic analyses have been done. The long-term objective of this research is to determine whether the production of bitter-tasting flavanone glycosides (neohesperidosides) in citrus can be manipulated using molecular genetic techniques. As a first step, cDNAs for chalcone synthase and chalcone isomerase, the first two biosynthetic enzymes specific to the flavonoid pathway, were isolated from a grapefruit leaf cDNA library using heterologous probes. Southern analyses showed that both genes appear to be part of multigene families, as expected. Northern analyses are underway to determine steady state mRNA levels in various grapefruit tissues, and Western blots to characterize protein expression are also being attempted.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 43 12 2
PDF Downloads 67 25 10