relations, cell membrane properties, and ethylene production and sensitivity ( Borochov and Woodson, 1989 ; Halevy and Mayak, 1979 , 1981 ; Shvarts et al., 1997 ). Spathe color in anthurium is the result of carotenoids such as chlorophyll or colored
Winston Elibox and Pathmanathan Umaharan
Xunzhong Zhang, E.H. Ervin and R.E. Schmidt
Ultraviolet-B [UV-B (280-320 nm)] radiation is one of the major factors causing quality decline of transplanted sod. Pigments and antioxidants are associated with plant stress resistance, but their roles in turfgrass tolerance to UV-B damage are not well understood. The objectives of this study were to determine if kentucky bluegrass (Poa pratensis L.) cultivars with darker green genetic leaf color possessed greater pigment and antioxidant defense capacities and if such characteristics were associated with greater resistance to UV-B. Two cultivars, `Moonlight' (dark green) and `Limerick' (light green), were selected and subjected to continuous, artificial UV-B radiation (70 μmol·m-2·s-1). UV-B irradiation reduced turf quality by 58% (`Moonlight') and 77% (`Limerick') relative to day 1 when measured 10 days after initiation of UV-B exposure. Higher canopy photochemical efficiency (PEc) was found in `Moonlight' relative to `Limerick' under UV-B stress and during recovery. `Moonlight' contained greater levels of chlorophyll (1.5 to1.6-fold), carotenoids (1.3-fold), superoxide dismutase [SOD (1.0-fold)] and catalase [CAT (1.5-fold)] than `Limerick' when measured at 10 days after UV-B initiation. Turfgrass quality and PEc were positively correlated with pigments (chlorophyll and carotenoids) and antioxidant enzymes (SOD and CAT), and negatively correlated with lipid peroxidation. The results suggest that selecting dark-green cultivars with greater pigment content and antioxidant activity may be an effective approach for turfgrass breeders and sod producers to improve tolerance of newly transplanted sod to environments with higher UV-B radiation.
Mark G. Lefsrud, John C. Sorochan, Dean A. Kopsell and J. Scott McElroy
resultant hybrid heat-tolerant bluegrass ( P. pratensis × P. arachnifera ) is reported to have the ability to survive heat stress events ( Su et al., 2007 ) and, from visual comparison, may be able to maintain tissue pigmentation [carotenoids and
Richard T. Olsen, John M. Ruter and Mark W. Rieger
Illiciums, or star-anises, have increased in popularity in the nursery and landscape industries. However, confusion exists as to which taxa are tolerant of high light intensities during production and subsequent establishment in the landscape. We investigated the effect of two light intensity treatments, 45% and 100% full sunlight, on gas-exchange parameters of five Illicium taxa: Illicium anisatum L., I. floridanum Ellis. `Pebblebrook', I. henryi Diels., I. lanceolatum A.C. Sm., and I. parviflorum Michx. Ex. Vent. `Forest Green'. Light-response curves were determined for individual leaves, and mean response parameters calculated. Chlorophyll and total carotenoids were analyzed after extraction in acetone, with total chlorophyll also estimated with a SPAD chlorophyll meter. In general, highest rates of CO2 assimilation (Amax) and lowest rates of dark respiration (Rd) were found in the 45% light treatment for all taxa. Both Illicium anisatum and I. floridanum `Pebblebrook' had substantial reductions in Amax in 100% light, 94% and 81% respectively, compared to plants grown in the 45% light treatment. Illicium henryi failed to survive the 100% light treatment. Illicium lanceolatum and I. parviflorum `Forest Green' were least affected by the 100% light treatment. Severe photooxidative bleaching was noted and confirmed by SPAD and pigment data, although SPAD readings were a poor predictor of total chlorophyll. For taxa of Illicium in our study, photosynthetic gas-exchange parameters and foliage pigment characteristics were improved in the low light treatment, suggesting optimal growth occurs in shaded conditions.
Celso L. Moretti, Steven A. Sargent, Donald J. Huber, Adonai G. Calbo and Rolf Puschmann
`Solar Set' tomatoes (Lycopersicon esculentum Mill.) were harvested at the mature-green stage of development and treated with 50 μL·L-1 ethylene at 20 °C. Breaker-stage fruit were dropped from 40 cm onto a solid surface to induce internal bruising and held along with undropped fruit at 20 °C. At the ripe stage, pericarp, locule, and placental tissues were analyzed for soluble sugars, vitamin C, pigments, titratable acidity, soluble solids content, pericarp electrolyte leakage, extractable polygalacturonase activity, and locule tissue consistency. Bruising significantly affected chemical composition and physical properties of pericarp and locule tissues, but not placental tissue. For bruised locule tissue, carotenoids, vitamin C, and titratable acidity were 37%, 15%, and 15%, lower, respectively, than unbruised fruit. For bruised pericarp tissue, vitamin C content was 16% lower than for unbruised tissue, whereas bruising increased electrolyte leakage and extractable polygalacturonase activity by 25% and 33%, respectively. Evidence of abnormal ripening following impact bruising was confined to locule and pericarp tissues and may be related to the disruption of cell structure and altered enzyme activity.
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.
Joshua R. Hyman, Jessica Gaus and Majid R. Foolad
Lycopene is the red pigment and a major carotenoid in tomato (Lycopersicon esculentum Mill.) fruit. It is a potent natural antioxidant, and the focus of many tomato genetics and breeding programs. Crop improvement for increased fruit lycopene content requires a rapid and accurate method of lycopene quantification. Among the various available techniques, high-performance liquid chromatography (HPLC) can be accurate, however, it is laborious and requires skilled labor and the use of highly toxic solvents. Similarly, spectrophotometric methods, although easier than HPLC, also require time-consuming extractions and may not be as accurate as HPLC, as they often overestimate fruit lycopene content. Colorimetric estimation of fruit lycopene using chromaticity values has been proposed as an alternative rapid method. Previous studies that examined the utility of this technique, however, were confined to the evaluation of only one or few cultivars and, therefore, lacked broad applicability. The purpose of the present study was to examine the utility of chromaticity values for estimating lycopene and β-carotene contents in tomato across diverse genetic backgrounds. Measurements of the chromaticity values (L*, a*, b*, C*, h*) were taken on whole fruit and purée of 24 tomato genotypes and were compared with HPLC measurements of fruit lycopene and β-carotene. Examination of different regression models indicated that a model based on the transformed value a*4 from purée measurements explained up to 94.5% of the total variation in fruit lycopene content as measured by HPLC. When this model was applied to a second set of fruit harvested at a later date from the same 24 genotypes, it explained more than 90% of the total variation in lycopene, suggesting its reliability. The best estimation for β-carotene content was obtained by using the b* chromaticity value from whole fruit measurements or the transformed a*2 value from purée measurements. Neither model, however, could explain more than 55% of the variation in β-carotene content, suggesting that chromaticity values may not be appropriate for estimating tomato β-carotene content. The overall results indicated that fruit lycopene content could be measured simply and rather accurately across a wide range of tomato genotypes using chromaticity values taken on fruit purée.
Kathleen G. Haynes, Lincoln Zotarelli, Christian T. Christensen and Stephanie Walker
-day adaptation to the United States ( Haynes, 1972 , 2008 ), hereinafter referred to as phu-stn. High levels of carotenoids have been reported in the long-day adapted phu-stn population ( Lu et al., 2001 ). Carotenoids may protect against a variety of chronic
Jane E. Lancaster, Carolyn E. Lister, Peter F. Reay and Christopher M. Triggs
The color of fruits and vegetables results from the presence of chlorophyll, carotenoid, and anthocyanin pigments. Instrumental measurements of color are used routinely in describing processes of changing color, such as fruit ripening. The applicability of using skin color measurements to predict changes in pigment composition was investigated using a wide range of fruit and vegetables. Skin color was measured using a Hunter Colorlab and represented as the coordinates X, Y, Z, L*, a*, b*, chroma (C*), and hue angle (ho). Identical skin samples were extracted and analyzed for chlorophyll, carotenoid, and anthocyanin concentration. Sets of pairwise scatter plots were generated for each set of color variables and for the chlorophyll, anthocyanin, and carotenoid pigments. There were linear relationships between ho and anthocyanin concentration and between L* and log [chlorophyll concentration]. Multiple regressions for each pigment variable and sets of color variables also were calculated. However, there was no unique linear combination of pigments that gave rise to a unique point in the color space. Conversely, a given set of coordinates in the color space can be accounted for by many combinations of pigments. Therefore, a given color measurement cannot be described in terms of a unique combination of pigments. Caution is urged in interpreting tristimulus color coordinates in terms of a simple change in pigment composition without prior knowledge of the pigment composition within the fruits and vegetables. The surface topography of fruits and vegetables may be of considerable significance in measuring color.
Peter M. Hanson, Ray-yu Yang, Jane Wu, Jen-tzu Chen, Dolores Ledesma, Samson C.S. Tsou and Tung-Ching Lee
Tomato (Lycopersicon esculentum Mill.) is among the most widely consumed vegetables worldwide and an important source of certain antioxidants (AO) including lycopene, β-carotene, and vitamin C. Improvement of tomato for content of AO and overall antioxidant activity (AOA) could potentially benefit human health in many countries. We evaluated 50 L. esculentum and three L. pimpinellifolium (L.) Mill. entries for contents of lycopene, β-carotene, ascorbic acid, total phenolics, and two assays for antioxidant activity [anti-radical power (ARP) and inhibition of lipid peroxidation (ILP)] for 2 years during the same period in south Taiwan. We detected high levels of genetic diversity for the AO and AOA measured in this study. Group means of the L. pimpinellifolium entries were significantly higher than L. esculentum group means for ARP, ILP, lycopene, ascorbic acid, phenolics, and soluble solids concentration, suggesting that introgression of alleles from L. pimpinellifolium may have potential to improve cultivated tomato for these traits. Ranking of entries for ILP and ARP were consistent between years, particularly for those entries with the highest means and these assays could be adopted by tomato breeders. Results from ILP and ARP assays were highly correlated (r = 0.82**) and it would be unnecessary to use both assays for tomato. Lycopene, β-carotene, ascorbic acid, soluble solids, and total phenolics were all positively correlated with ARP. Among AO, total phenolics content was most closely associated with ARP (r = 0.90**) and ILP (r = 0.83**); this suggests that phenolics make a major contribution to AOA in tomato fruit. Fruit size was negatively correlated with ARP (r = -0.74**) and ILP (r = -0.71**), indicating that combining large fruit size and high AOA will be challenging.