Quantifying Vitamin C and Flavonoid Levels In a Unique F2 Pepper Family

Peppers (Capsicum spp.) are a diverse group of economically important plants that have gained attention for containing various phytochemicals in their fruit tissue; some of these phytochemicals have beneficial effects on the health of people who consume them on a regular basis.  Laboratory analysis has confirmed pepper fruit contains carotenoids, polyphenolics, capsaicinoids, flavonoids, and various vitamins (Howard et al., 2000).  Of these, vitamin C (ascorbic acid) and flavonoids (quercetin and luteolin) are currently being targeted for genetic improvement.  As more people learn of the importance a healthy diet can play in the longevity of their life, development of fruits and vegetables with elevated levels of these different compounds will progress.  Previously, our extensive screening for flavonoid levels in diverse pepper germplasm identified extremely high concentrations of quercetin and luteolin in line CA377.  In March of 2008, we planted approximately 150 F₂ progeny of the cross - CA377 x B22, at the Texas AgriLife research station in Uvalde, TX.  Plants were grown with commercial practices, and fully mature fruit were harvested and transported to College Station, TX.  Peppers were held at -80^O C until they were analyzed at the analytical core unit of the Vegetable and Fruit Improvement Center.  3% meta-phosphoric acid and 100% methanol were the solvents used to extract vitamin C and flavonoids respectively.  At the end of the preparation process, each sample was inserted into a High-Performance Liquid Chromatography (HPLC) machine to complete the analysis.  An alpha bond amino 10μm isocratic column (254nm, 0.8ml/min., 10 min.) and a Nova-pak C-18 4μm isocratic column (0.5% H₃PO₄, 360nm, 1ml/min, 20 min.) were used for vitamin C and flavonoids respectively.  Vitamin C levels varied between 500 and 2,000 μg/g while total flavonoid levels varied from 85 to 500 μg/mL.  DNA was also extracted from leaf tissue of each F₂ progeny plant.  This data is currently being utilized to screen DNA bulks from high and low progeny as well as both parents to identify polymorphic RAPD markers.  Reproducible candidate markers will be utilized to screen all progeny to confirm linkage to major QTL contributing to elevated levels of vitamin C and flavonoids.  The goal is to enhance marker assisted selection for relevant fruit quality genes.