ARS | Publication request: Evaluation of grapefruit plants transformed with genes from the flavanoid pathway

Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract
Publication Acceptance Date: July 20, 2005
Publication Date: July 20, 2005
Citation: Koca, U., Berhow, M.A., Eyal, Y., Frydman, A., Moore, G. 2005. Evaluation of grapefruit plants transformed with genes from the Flavanoid pathway [abstract]. Plant Biology Annual Meeting. p. A634.

Technical Abstract: Flavonoids are the largest class of secondary metabolites functioning mostly in scavenging of free radicals; in protection from UV light; in pollination and seed dispersal via their color features in plants. Many flavonoid compounds have variety of biological activities in animals, such as anticarcinogenic, antioxidant, anti-inflammatory, anti-allergic and anti-mutagenic. The flavanone glycosides are the major flavonoids in citrus, which are produced throughout the plant. They affect the taste rather than color. Flavanone rutinosides are tasteless, while flavanone neohesperidosides are bitter. Naringin is the major bitter compound in grapefruit, which deprives consumers of having the nutritional and health benefits of them. Our main goal is to manipulate the biosynthesis of flavanone glycosides in grapefruit using molecular genetics and transformation techniques in order to decrease the bitter taste or increase the pharmacological value. cDNAs of the structural genes chalcone synthase (CHS) and chalcone isomerase (CHI) were isolated from citrus at the beginning of the project. Sense and antisense constructs of these cDNAs were transferred to grapefruit to suppress the target gene expression and/or increase the nonbitter flavonoid compounds which may have pharmacological benefits. Further, sense and hairpin (hp) forming constructs of the 1,2 rhamnosyl transferase (1,2 RT) cDNA, which catalyzes the last biochemical step in the production of naringin were utilized for the transformation. Transformed plants were evaluated for their transgene copy numbers via molecular techniques and flavonoid content by HPLC. They are being evaluated for their morphology and steady state RNA levels.