Beverly Clevidence, Inke Paetau and J. Cecil Smith Jr.
Wenhe Lu, Kathleen Haynes, Eugene Wiley and Beverly Clevidence
The yellow pigment in potato (Solanum L. sp.) tuber flesh is caused by various carotenoids that may protect against cancer, cardiovascular disease, and macular eye degeneration. The objectives of this research were to 1) identify and quantify the carotenoids present in 11 diploid clones from a hybrid population of Solanum phureja ssp. phureja Juz. & Bukasov-S. stenotomum ssp. stenotomum Juz. & Bukasov and two tetraploid potato cultivars (the yellow-fleshed `Yukon Gold' and the white-fleshed `Superior'), and 2) determine the relationship between tuber yellow intensity and carotenoid content. Yellow intensity was measured by a colorimeter programmed to calculate a yellowness index, YI E-313. Carotenoid analyses were performed on an automated high-performance liquid chromatography system with software for integration and quantitation with detection at 450 nm using a diode array detector. Six major carotenoids were detected: neoxanthin, violaxanthin, lutein-5,6-epoxide, lutein, zeaxanthin, and an unknown carotenoid. Total carotenoid content in the yellow-fleshed diploid clones was 3 to 13 times higher than `Yukon Gold' and 4 to 22 times higher than `Superior'. Both total and individual carotenoid contents were positively correlated with tuber yellow intensity. There was an exponential relationship between total carotenoid content and tuber yellow intensity. This suggests that selecting for more intense yellow flesh will result in higher levels of carotenoids. These specific diploid clones were selected for this study because they produced at least five percent 2n pollen; they have the potential to make significant contributions to improving the nutritional status of tetraploid potatoes through 4x-2x hybridizations.
Kathleen G. Haynes, Beverly A. Clevidence, David Rao and Bryan T. Vinyard
Carotenoids have a wide range of human health benefits. Yellow-fleshed tetraploid potato (Solanum tuberosum) cultivars have more than twice the concentration of carotenoids as white-fleshed cultivars. However, carotenoid concentrations in some diploid potatoes have been reported to be up to 13 times higher than in ‘Yukon Gold’, the most popular yellow-fleshed potato cultivar grown in the United States, and up to 22 times higher than in white-fleshed potatoes. The purpose of this study was to determine the feasibility of using these high-carotenoid diploids to develop high-carotenoid tetraploid germplasm. Three diploid clones with high (dark yellow-flesh), moderate (moderate yellow-flesh), and low (white–cream-flesh) carotenoid levels that produced 2n pollen were crossed with a light yellow-fleshed tetraploid advanced breeding selection to determine the inheritance of carotenoid content. Twenty-six to 43 progeny from these three 4x-2x families were grown in a replicated field experiment in Presque Isle, ME, for 2 years. After harvest, carotenoids were extracted and quantified by high-performance liquid chromatography in 13 to 14 randomly selected clones from each family; however, flesh color was scored as white or yellow in all progeny. A continuous distribution of carotenoid concentration with high- and low-carotenoid segregants was observed in all three families. There were no significant differences among these three families for individual or total carotenoid concentrations; however, there were significant differences among clones within families. Broad-sense heritability estimates were high for total carotenoid (0.81), lutein (0.77), zeaxanthin (0.73), and the lycopene beta-cyclase pathway carotenoids (0.73); moderate for neoxanthin (0.42); and low for violaxanthin (0.21) and antheraxanthin (0.13). Based on flesh color segregation, the two yellow-fleshed diploid parents were heterozygous for the Chy2 allele governing yellow-flesh and produced 2n gametes by a second division restitution mechanism. It appears that selection for high-carotenoid tetraploid germplasm can be made from within any family with at least one yellow-fleshed parent. Selections will have to be made on an individual clonal basis rather than on a family basis.
Ingrid M. Fordham, Beverly A. Clevidence, Eugene R. Wiley and Richard H. Zimmerman
Autumn olive (Elaeagnus umbellata Thunb.) has edible fruit with brilliant red or yellow pigmentation. An analysis of the pigment in fruit of five cultivars and six naturalized plants showed that the berries contain lycopene, α-cryptoxanthin, β-cryptoxanthin, β-carotene, lutein, phytoene, and phytofluene. The lycopene content per 100 g ranged from 15 to 54 mg in fresh fruit from the naturalized plants and from 17 to 48 mg in the four cultivars with red-pigmented fruit. A cultivar with yellow fruit had only 0.47 mg/100 g fresh fruit. In contrast, fresh tomato fruit, the major dietary source of lycopene, has a lycopene content per 100 g of ≈3 mg. This newly identified source of lycopene may provide an alternative to tomato as a dietary source of lycopene and related carotenoids.
Kathleen G. Haynes, Beverly A. Clevidence, David Rao, Bryan T. Vinyard and J. Marion White
Consumption of carotenoid-containing foods can promote human health. Although yellow-fleshed potatoes (Solanum tuberosum) have a higher carotenoid content than white-fleshed potatoes, little is known about how growing environments may affect individual and total carotenoid content in different potato clones. The purposes of this study were to estimate the amount of genetic variability in potato for five xanthophyll carotenoids, their concentration, and to determine the stability of these carotenoids across environments. Nine white- or yellow-fleshed tetraploid clones were grown in Maine and Florida for 2 years. Carotenoids were extracted in acetone and analyzed by high-performance liquid chromatography. There were significant differences among clones for zeaxanthin, antheraxanthin, lutein, and total carotenoid content. There were significant clone × environment interactions for zeaxanthin, antheraxanthin, violaxanthin, neoxanthin, lutein, and total carotenoid. Broad-sense heritabilities (and their 95% confidence intervals) were 0.89 (0.79–0.98) for zeaxanthin, 0.93 (0.87–0.99) for antheraxanthin, 0.68 (0.14–0.92) for violaxanthin, 0.51 (0.00–0.88) for neoxanthin, 0.85 (0.70–0.97) for lutein, and 0.96 (0.89–0.99) for total carotenoid. Clonal mean total carotenoid content ranged from 101 to 511 μg/100 g fresh weight. A higher proportion of carotenoids were produced by the lycopene epsilon cyclase branch of the carotenoid biosynthetic pathway in white-fleshed than yellow-fleshed clones. Total carotenoid content in B2333-5 was significantly greater than in ‘Yukon Gold’. With genetic variation for individual and total carotenoid content in potatoes, improving the levels of carotenoids has been and should continue to be feasible; however, concentrations are likely to vary in different environments.
Craig S. Charron, Steven J. Britz, Roman M. Mirecki, Dawn J. Harrison, Beverly A. Clevidence and Janet A. Novotny
Isotopic labeling of plants provides a unique opportunity for understanding metabolic processes. A significant challenge of isotopic labeling during plant growth is that isotopes must be administered without disrupting plant development and at sufficient levels for mass spectral analysis. We describe a system for isotopic labeling of leafy vegetables with 13C and demonstrate successful incorporation of 13C into anthocyanins of preheading red cabbage (Brassica oleracea L. var. capitata L.). ‘Super Red’ red cabbage seedlings were grown for 34 days in an airtight acrylic labeling chamber supplied with 13CO2 to maintain 400 μL·L−1. Nutrient solution was delivered hydroponically without allowing infusion of natural CO2 into the labeling chamber. Plants were initially grown at 22 °C ± 1 °C in constant light of 228 μmol·m−2·s−1. Upon canopy closure, anthocyanin development was promoted by reducing the nutrient solution concentration and reducing the temperature to 10.5 °C ± 1.5 °C. Total shoot fresh weight (FW) was 1556 g and root FW was 491 g at harvest. Analysis of red cabbage shoot tissue by high-performance liquid chromatography/tandem mass spectrometry indicated the presence of 37 anthocyanins, of which 14 are reported here for the first time. Mass shifts representing 13C incorporation into anthocyanins were evident in mass spectra of anthocyanins from labeled tissue and demonstrate successful isotopic labeling.