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Milton E. McGiffen Jr. and Edmund J. Ogbuchiekwe

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

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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

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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

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Philipp Simon

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.

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P.W. Simon

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.

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Beiquan Mou

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.

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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

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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

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Thomas C. Koch* and Irwin L. Goldman

Carotenoids (provitamin A) and tocopherols (vitamin E) are powerful antioxidants in plants and in the human diet. Carrot (Daucus carota) has been selected for increased levels of carotenoids, contributing to its orange color and reported health benefits. Selection for increased tocopherol has shown success in seed oils, but little progress has been made in the edible portions of most vegetable crops. HPLC measurement following a simultaneous heptane extraction of both compounds has shown a significant (P ≤ 0.001) positive correlation of α-tocopherol with α-carotene (r = 0.65) and β-carotene (r = 0.52). To increase both the tocopherols and carotenoids in plants, 3 populations have been established from select open-pollinated varieties grown in 2002. These populations consist of half-sib families with these differing selection schemes: based strictly on increased α-tocopherol levels; an index to increase α-carotene, β-carotene and α-tocopherol; and a random population in which no selection is occurring. After one cycle of selection, populations were grown on muck soil during the summer of 2003. Compared with the random population, an increase of 24.68% in α-tocopherol concentration was recorded for the population selected strictly on α-tocopherol while increases of 8.47% in α-tocopherol, 9.31% in α-carotene and 7.31% in β-carotene were recorded for the population with index selection. The continuation of these carrot populations shows promise to produce carrot germplasm with improved human nutritive value.

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Alexandra B. Napier, Kevin M. Crosby, and Soon O. Park

Muskmelons (Cucumis melo L.) play an important role in the American diet. Ranked as one of the top 10 most-consumed fruits by the USDA, cantaloupe melons have the highest amount of beta-carotene of all the ranked fruits. Beta-carotene, also called pro-Vitamin A, is an essential nutrient required for eye health, and may have the potential, as an antioxidant to reduce the risks associated with cancer, heart disease, and other illnesses. Breeding melons with increased levels of beta-carotene will benefit consumer health. Research has found phytonutrients are most bioavailable when consumed in their fresh form, rather than as vitamin supplements. The high level of beta-carotene found in some melons has a genotypic component, which may be exploited to breed melons high in beta-carotene. Molecular markers and marker-assisted selection (MAS) can be used to increase the efficacy of the breeding process, while lowering breeding costs. An F2 population was created using `Sunrise', the female parent, containing no beta-carotene crossed with `TAM Uvalde', a high beta-carotene variety. A field population consisting of 115 F2 individuals and a greenhouse population containing 90 F2 individuals were grown. The resulting fruit were screened phenotypically and ranked according to beta-carotene content. Chisquare values fit the previously reported model of a single dominant gene for presence of beta-carotene (orange-flesh) vs. absence (green or white flesh). A continuous distribution of beta-carotene concentrations from high to low suggested quantitative inheritance for this trait. Two eight-plant DNA bulks composed of either high or low beta-carotene F2 individuals were screened for polymorphic molecular markers using the amplified fragment-length polymorphism technique.