We thank Tony Vanden Hombergh and Carrie Young of Kalsec, Inc. for spectrophotometric analysis of root tissue, Anwar Ali and Carol Lovatt of the Univ. of California for preparation of the beta-carotene standard curve, Grimmway and Bolthouse
Milton E. McGiffen Jr. and Edmund J. Ogbuchiekwe
Philipp W. Simon, Xenia Y. Wolff, C. E. Peterson, Dale S. Kammerlohr, Vince E. Rubatzky, James O. Strandberg, Mark J. Bassett, and J. M. White
Carotenes from vegetables and fruits are vitamin A precursors that contribute about half of the vitamin A in the U.S. diet (3) and two-thirds of the world diet (5). Carrots typically contain 65 to 90 ppm carotenes (1) and are estimated to be the major source of carotene for U.S. consumers (3). Few pro-vitamin A sources surpass the carotene content of typical carrots, although red palm oil can contain >825 ppm carotenes (2). Genetic selection for higher carotene levels in carrots could increase the dietary consumption of carotene and consequently vitamin A. A high carotene mass carrot population was developed for use in breeding, genetic, and biochemical studies of carrot (Fig. 1).
Stephanie Rossi and Bingru Huang
carotenes or xanthophylls, depending on their molecular structure and where they are located in the chloroplast ( Zaripheh and Erdman, 2002 ). More specifically, carotenes are localized in the core complexes of photosystems I and II, whereas xanthophylls are
Nan Wang, Shi Liu, Peng Gao, Feishi Luan, and Angela R. Davis
abundant carotenoid. In contrast, white-fleshed watermelon contains only trace amounts of carotenoids. Orange-fleshed watermelon contains β/ζ-carotene, prolycopene, and phytoene, and yellow-fleshed watermelon mainly contains violaxanthin and/or neoxanthin
Fekadu Gurmu, Shimelis Hussein, and Mark Laing
another major focus area, among which improving β-carotene content (provitamin A) is the top priority. Breeding for high β-carotene content is crucial because vitamin A deficiency (VAD) is a serious health problem that results in blindness, weak resistance
A six-parent diallel which included carrot inbreds with a range of carotene content from 80 to 490 ppm was evaluated over 2 years. General combining ability accounted for most of the variation observed. Phenotypic mass selection was exercised for high carotene content in three carrot populations. Response to selection continued to be high in one population, HCM, after 11 cycles of selection. In contrast, after three generations of selection, little progress was able to be made in a population derived from primarily Nantes-type open-pollinated cultivars. Realized heritability estimates varied from 15% to 49%. Environment contributed significantly to variation in carotene content.
Genes for reduced carotene content (white, yellow, and pale orange) and for anthocyanin pigmentation were identified in Daucus carota PI 173687 and in progeny derived from crosses of this Plant Introduction with orange-rooted inbred lines. Monogenic inheritance for each of these root color variants was examined. Mixed cell cultures of callus derived from white and orange roots indicated autonomy of carotene gene expression in carrot cell cultures. Strategies for incorporation of carrot genes conditioning pigment content will depend upon gene combinations sought.
There is increasing medical evidence for the health benefits derived from dietary intake of carotenoid antioxidants, such as β-carotene and lutein. Enhancing the nutritional levels of vegetables would improve the nutrient intake without requiring an increase in consumption. A breeding program to improve the nutritional quality of lettuce (Lactuca sativa L.) must start with an assessment of the existing genetic variation. To assess the genetic variability in carotenoid contents, 52 genotypes including crisphead, leaf, romaine, butterhead, primitive, Latin, and stem lettuces, and wild species were planted in the field in Salinas, Calif., in the Summer and Fall of 2003 with four replications. Duplicate samples from each plot were analyzed for chlorophyll (a and b), β-carotene, and lutein concentrations by high-performance liquid chromatography (HPLC). Wild accessions (L. serriola L., L. saligna L., L. virosa L., and primitive form) had higher β-carotene and lutein concentrations than cultivated lettuces, mainly due to the lower moisture content of wild lettuces. Among major types of cultivated lettuce, carotenoid concentration followed the order of: green leaf or romaine > red leaf > butterhead > crisphead. There was significant genetic variation in carotenoid concentration within each of these lettuce types. Crisphead lettuce accumulated more lutein than β-carotene, while other lettuce types had more β-carotene than lutein. Carotenoid concentration was higher in summer than in the fall, but was not affected by the position of the plant on the raised bed. Beta-carotene and lutein concentrations were highly correlated, suggesting that their levels could be enhanced simultaneously. Beta-carotene and lutein concentrations were both highly correlated with chlorophyll a, chlorophyll b, and total chlorophyll concentrations, suggesting that carotenoid content could be selected indirectly through chlorophyll or color measurement. These results suggest that genetic improvement of carotenoid levels in lettuce is feasible.
Silver Tumwegamire, Regina Kapinga, Patrick R. Rubaihayo, Don R. LaBonte, Wolfgang J. Grüneberg, Gabriela Burgos, Thomas zum Felde, Rosemary Carpio, Elke Pawelzik, and Robert O.M. Mwanga
-fleshed. Carotenoid pigments provide OFSP storage roots the orange flesh color. More than 60 mg total carotenoids in 100 g DM have been reported ( Woolfe, 1992 ). A constant high proportion (≈90%) of β-carotene in relation to total carotenoids in OFSP has been known
Jack E. Staub, Philipp W. Simon, and Hugo E. Cuevas
The Agricultural Research Service, U.S. Department of Agriculture, released the high β-carotene cucumber ( Cucumis sativus var. sativus L.) line EOM 402-10 in Jan. 2011. Line EOM 402-10 was made available to U.S. cucumber breeders to supply a