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Dean A. Kopsell, David E. Kopsell and Joanne Curran-Celentano

Therapeutic compounds in herbal crops are gaining recent attention. Sweet basil (Ocimumbasilicum L.) is a popular culinary herbal crop grown for both fresh and dry leaf markets. Recently, basil (unidentified cultivar) was shown to rank highest among spices and herbal crops for xanthophylls carotenoids. This class of carotenoids is associated with decreased risks of certain cancer and age-related eye diseases. The research goal for the current study was to characterize the concentrations of nutritionally important carotenoid pigments among popular varieties of basil. Eight cultivars of sweet basil (`Genovese', `Italian Large Leaf', `Nufar', `Red Rubin', `Osmin Purple', `Spicy Bush', `Cinnamon', and `Sweet Thai') were grown in both field and greenhouse environments and evaluated for plant pigments using HPLC methodology. Environmental and cultivar differences were significant for all of the pigments analyzed. `Sweet Thai' accumulated the highest concentrations of lutein, zeaxanthin, and beta-carotene carotenoids, while `Italian Large Leaf' had the lowest concentrations. Comparing the two environments, cultivar means for carotenoid and chlorophyll pigments were higher in the field environment when expressed on both a fresh and dry weight basis. Exceptions were found only for the purple leaf basils (`Osmin Purple' and `Red Rubin'). Positive and highly significant correlations existed between carotenoid and chlorophyll pigments in both environments. This study demonstrates that sweet basil can accumulate high levels of nutritionally important carotenoids in both field and greenhouse environments.

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C.R. Brown, D. Culley, C.-P. Yang, R. Durst and R. Wrolstad

A breeding effort designed to increase the antioxidant level of potato (Solanum tuberosum L.) by means of high concentrations of anthocyanins and/or carotenoids provided selected materials for analysis. Extraction methods suitable for isolating both hydrophilic and lipophilic compounds were used and measurements of total anthocyanin and total carotenoid were made. Two methods of measurement of oxygen radical absorbance capacity (ORAC) adapted to hydrophilic and lipophilic compounds were applied. Total anthocyanin values varied between 9.5 and 38 mg per 100 g fresh weight (FW). The hydrophilic fraction ORAC measurements among anthocyanin-rich clones varied between 250 and 1420 μmol Trolox equivalents per 100 g FW. These two variables were significantly correlated, r = 0.73, and with significant positive slope in linear regression. Measurement of total carotenoids revealed differing degrees of yellowness covered a range of total carotenoid extending from 35 to 795 μg per 100 g FW. Dark yellow cultivars had roughly 10 times more total carotenoid than white-flesh cultivars. The lipophilic fraction ORAC values ranged from 4.6 to 15.3 nmoles α-tocopherol equivalents per 100 g FW. Total carotenoid was correlated with the lipophilic ORAC values, r = 0.77, and also had a statistically significant positive regression coefficient. Clones with red and yellow pigments visible in the flesh had anthocyanins and carotenoids in elevated levels and ORAC contributions from both fractions. The introgression of high levels of carotenoid from germplasm directly extracted from the Papa Amarilla (yellow potato) category of cultivars of South America into long-day adapted North American materials is presented here. Although anthocyanins and carotenoids are major contributors to antioxidant activity, other constituents of potato flesh likely play significant roles in total antioxidant values.

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Thomas C. Koch and Irwin L. Goldman

Carotenoids and tocopherols are health-functional phytochemicals that occur in a wide range of fruit and vegetable crops. These two classes of compounds are synthesized from a common precursor, geranyl-geranyl pyrophosphate, and are typically analyzed separately via high-performance liquid chromatography (HPLC) techniques. Because carotenoids and tocopherols are present in many edible horticultural crops, it would be advantageous to measure them simultaneously in plant tissues. Herein we report a one-pass reverse-phase HPLC method for extraction and analysis of carotenoids and tocopherols in carrot that can be extended to other high-moisture plant organs. Elution times ranged from 5 minutes for α-tocopherol to 24 minutes for β-carotene. This method improves the efficiency of analyzing these compounds by up to 50%, and should increase the efficiency of assessing carotenoid and tocopherol profiles in horticultural crops.

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W.Y.L. Poon and I.L. Goldman

Carotenoids have been shown to be important both nutritionally and medicinally. Carotenoid accumulation was compared during growth and storage of four carrot genotypes: YY y1y1y2y2RPRP, yyY1 Y1Y2Y2 RPRP, YY Y1 Y1Y2Y2 RPRP, and rprp. These genotypes exhibit orange, yellow, white, and pale-orange roots respectively. The orange and pale-orange genotypes are near-isogenic for rp, a gene that reduces total carotenoid content by 93%. Genotypes were grown in replicated field plots during 1996 and stored for 8 months at 4°C. Samples of root tissue were removed at 7-day intervals during vegetative growth and 4-week intervals during the postharvest period. Total carotenoid content were quantified using HPLC and spectrophotometric analyses. Increases in carotenoid content of 119% and 79% in rprp and YY y1y1y2y2RPRP and decreases of 6% and 64% in YYY1 Y1Y2Y2RPRP and yyY1 Y1Y2Y2RPRP, respectively, were measured between 62 and 100 days after planting. At 100 days after planting, YY y1y1y2y2RPRP exhibited 10-fold greater carotenoid content than rprp. Carotenoid content in yyY1 Y1Y2Y2RPRP and YY y1y1y2y2RPRP increased during the first 28 days of storage and decreased subsequently. Meanwhile, rprp began to decrease in carotenoid content at day 14 of storage. HPLC analysis at l = 445 nm revealed two large unique peaks in rprp with elution times of 27 and 28.7 minutes that were of lesser abundance in YY y1y1y2y2RPRP, suggesting that the rate of β- and α-carotene accumulation is not the only difference between YY y1y1y2y2RPRP and rprp.

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W.Y.L. Poon and I.L. Goldman

The rp allele causes a significant reduction in total carotenoid pigmentation in carrot (Daucus carota L.) roots. The objective was to investigate the effect of rp on the composition, accumulation, and retention of carotenoids in two near-isolines of carrot, W266RPRP and W266rprp, during vegetative growth and postharvest storage. Field experiments were conducted during 1996 and 1997 in which roots were sampled weekly from 62 to 100 days after seed-sowing and biweekly during postharvest storage at 4 °C up to 386 days after sowing. Linear increases in total carotenoid concentration were observed for W266RPRP and W266rprp during vegetative growth. The average daily rate of increase in total carotenoid concentration in W266RPRP and in W266rprp was 12.7 and 1.3 mg·g-1 dry weight, respectively. A linear decrease in carotenoid concentration was measured for W266RPRP but not for W266rprp during postharvest storage. At 100 days after sowing, high-performance liquid chromatography analyses showed W266rprp had 20-fold lower concentrations of a-carotene and 50-fold lower concentrations of β-carotene in root tissue compared to W266RPRP. Levels of β-carotene and lutein in the first true leaves were reduced by ≈50% in W266rprp compared to W266RPRP. Results from this investigation suggest that the rp allele affects the concentration of root and foliage carotenoids, as well as the rate of carotenoid accumulation and degradation in carrot roots. The impact of the rp allele is far greater in root tissue than in foliage, suggesting it may act as a transcription factor or structural gene affecting primarily root carotenoid biosynthesis.

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Marisa M. Wall, Cynthia A. Waddell and Paul W. Bosland

The β-carotene and total carotenoid content of either fresh or dried tissue of fruits of a total of 57 cultivars of six Capsicum species were analyzed using high performance liquid chromatography (HPLC). β-Carotene levels in ripe fruit varied from 0 to 166 μg·g-1 fresh weight, and carotenoid levels were from 1 to 896 μg·g-1 in ripe fruit in 1996. The range of values for β-carotene was similar in 1997, but that for total carotenoids was wider (4 to 1173 μg·g-1 fresh weight). Fresh fruit of the cultivars Greenleaf Tabasco, Pulla, Guajillo, NuMex Conquistador, Ring-O-Fire, and Thai Dragon contained greater amounts of β-carotene per 100 g fresh weight than the recommended dietary allowance (RDA) for vitamin A for the average adult. For dried Capsicum entries, New Mexican, aji, pasilla, and ancho types had the highest levels of β-carotene. In 1996, β-carotene levels among the dried Capsicum germplasm ranged from 2 to 739 μg·g-1 dry weight, and carotenoid levels from 111 to 6226 μg·g-1. Values were higher in 1997, ranging from 24 to 1198 μg·g-1 dry weight for β-carotene and from 187 to 10,121 μg·g-1 for total carotenoids. A pasilla type (C. annuum L.) had the highest total carotenoid content among the dried entries in both years.

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Marisa Wall, Cynthia Waddell, Paul Bosland and Stephanie Walker

The β-carotene and total carotenoid content of different Capsicum fruit types and species were analyzed using HPLC. This information is useful for breeding high carotenoid chiles (New Mexican type) for the food industry, and also provides nutritional data for the range of fruit types within the Capsicum genus. Fresh fruit from 25 accessions and dried fruit from 39 accessions were evaluated in 1996 and 1997. β-carotene levels varied from 0 to 16.6 mg/100 g fresh weight, and carotenoid levels were from 0.1 to 89.6 mg/100 g in red ripe fruit in 1996. The range of values for β-carotene was similar in 1997, but a wider range in total carotenoids (0.4 to 117.3 mg/100 g fresh weight) was observed. Fresh fruit (100 g) of the cultivars `Greenleaf Tabasco', `Pulla', `Guajillo', `NuMex Conquistador', `Ring-O-Fire', and `Thai Dragon' contained greater amounts of β-carotene than the RDA for vitamin A for the average adult. For dried Capsicum entries, New Mexican, aji, pasilla, ancho, and guajillo types had the highest levels of β-carotene. In 1996, β-carotene levels among the dried Capsicum germplasm ranged from 0 to 739.2 μg/g dry weight, and carotenoid levels were from 21.3 to 6,225.9 μg/g. Values were higher in 1997, and ranged from 23.7 to 1,198.1 μg/g dry weight for β-carotene and from 76.9 to 10,120.6 μg/g for total carotenoids. A pasilla type (C. annuum) had the highest total carotenoid content among the dried entries in both years.

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Brian J. Just* and Philipp W. Simon

While the carotenoid biosynthetic pathway has been studied several horticultural and agronomic crops, very little information exists for this conserved pathway in carrot, a primary source of dietary carotenoids. Though orange carrots are the most familiar color to Western consumers, yellow, red, and white carrots also exist and have been historically important. Modern carrot breeders are showing renewed interest in these unusual color phenotypes. Beta- and alpha-carotene are the primary pigments in orange carrot roots. Yellow carrots accumulate xanthophylls (oxygenated carotenes), red carrots accumulate lycopene (the precursor to alpha- and beta-carotene), and white carrots accumulate no detectable pigments. Differences between these phenotypes are usually monogenic or oligogenic. Our research has focused on identifying putative genes for carotenoid biosynthetic enzymes in the carrot genome, mapping them, and examining expression patterns in various tissues and carrot root pigment phenotypes. We are using this information to create a carrot pigment biosynthesis function map incorporating biosynthetic enzymes, major carrot color genes, and gene expression information.

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José A. Narváez, Patricia Flores-Pérez, Virginia Herrera-Valencia, Fernando Castillo, Roberto Ku-Cauich, Blondy B. Canto-Canché, Nancy Santana Buzzy and Renata Rivera-Madrid

The tropical plant Bixa orellana L. (annatto) is the sole source of bixin, the most frequently employed natural pigment in the food industry. Little is known about the physiology, biochemistry, and molecular genetics of this crop. Our purpose was to establish a set of analytical tools that could be applied in the genetic improvement of B. orellana, particularly for the screening of characteristics such as bixin content and resistance to diseases or pests. Some preliminary results on the study of carotenoid synthesis are presented. In vitro cultures from several B. orellana tissues were established and DNA, RNA, and proteins were extracted from them and analyzed. Similarly, bixin and total carotenoids were quantified.

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Haejeen Bang*, Daniel I. Leskovar and Kilsun Yoo

This experiment was conducted to determine the effects of deficit irrigation and growing season on fruit quality, carotenoid content and yield of red-, orange-, and yellow-fleshed diploid and triploid watermelon. Irrigation rates were 1.0 evapotranspiration (ET) and 0.5 ET. Diploid cultivars were Summer Flavor 710 (red), Tendersweet (orange), and Summer Gold (yellow). Triploid cultivars were Summer Sweet 5244 (red), Sunshine (orange), and Amarillo (yellow). Four-week old containerized transplants were planted in the field at TAES-Uvalde on 27 Mar. and 21 May 2003. Deficit irrigation imposed after plants were fully established reduced the individual fruit weight and size in the early planting. Soluble solids content (SSC) and firmness was not affected by irrigation rate in both plantings. SSC varied across cultivars and increased with maturity, particularly for the triploid cultivar Amarillo. In general, triploids were firmer than diploid cultivars. Total carotenoid content was not affected by irrigation during early planting. Diploid and triploid red-fleshed watermelon cultivars had significantly higher carotenoid content than orange- and yellow-fleshed cultivars. The major carotenoid was lycopene (more than 65%), followed by prolycopene (20%) and B-carotene (7%).