Progress 10/01/07 to 09/30/10
Outputs
OUTPUTS: During the past four years we completed studies of carotenoid content and profiles in breeding lines and selected varieties of squash. Visual methods for evaluating carotenoids were useful for selecting cultigens with high carotenoid content; however, spectrophotometric analysis often revealed variability in carotenoid content not readily ascertained visibly. Because of large genetic variability in carotenoid profiles, especially in the species Cucurbita moschata, HPLC analysis was needed for proper nutritional evaluation. Our data corroborate earlier studies showing increases in total carotenoid content during storage, but more importantly show that (1) a large proportion of total carotenoid content in fruits of most C. maxima cultigens and many C. moschata cultigens are those not identified as nutritionally beneficial, and (2) the nutritionally important carotenoid, beta-carotene, is preferentially enriched during storage of fruit. Increases in carotenoids during storage of fruit were highly correlated with increases in soluble solids content (primarily sugars), but were not associated with changes in dry matter. Although fruit of C. moschata and C. maxima cultigens appeared mature in terms of rind color and fruit size at 40 days after pollination (DAP), soluble solids and carotenoid levels were low. In C. maxima, fruit often attained acceptable eating quality and carotenoid content by the 60 day harvest period; whereas, fruit of C. moschata required an additional 30 to 60 days of storage at 15 C (after ripening period) to reach acceptable levels of soluble solids and near maximum carotenoid content. The after-ripening period in C. moschata could be reduced to two or three weeks by storing squash at higher temperatures (28 C daytime and 18 C nighttime temperatures) in a greenhouse. There was some seasonal variability in carotenoid content over three years of study, but in general, the relative differences in carotenoid content among cultigens remained the same. The major nutritionally beneficial carotenoids in C. maxima and C. moschata cultigens examined in this study were beta-carotene and lutein, the latter a key photoprotective pigment in the macula region of the eye. Zeaxanthin, another major macular pigment, was found in small amounts (about 5% of total) in some C. maxima cultigens. In most cultigens, lutein and zeaxanthin were in an esterified form, but in one breeding line about 70% of the lutein is non-esterified. Alpha-carotene comprised up to 13% of total carotenoids in a few C. moschata cultigens, but was absent in C. maxima cultigens. Although three commercial varieties of C. moschata averaged only about 20% beta-carotene, one breeding line contained over 50% beta-carotene. PARTICIPANTS: The project directors for this study were Dr. J. Brent Loy, Department of Biological Sciences and Dr. Joanne Curran-Celentano, Department of Molecular, Cellular and Biomedical Sciences. The lead researcher was Jennifer Noseworthy, a doctoral student in Plant Biology. Technical assistance in high pressure liquid chromatography was provided by Susan Jahlbert, a laboratory technician. Important technical assistance and guidance was provided by Dr. Dean Kopsell, an Associate Professor at the University of Tennessee, and acknowledged authority on plant carotenoids. TARGET AUDIENCES: The target audiences to date have been other research personnel, chiefly those working with cucurbit crops, vegetable extension specialists, and vegetable growers. There has been some effort to reach the consumer level through popular articles. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Nutritional surveys of plant foods sold in supermarkets are conducted by the USDA and provide useful dietary information for the consumer. Nonetheless, such surveys are not specific to varieties, and in the case of carotenoid content of vegetables, do not specify content of the nutritionally beneficial carotenoids. Carotenoids are a class of fat soluble, orange-pigmented, complex molecules, some of which are important human nutrients. Beta-carotene, important in development and eye function, is most widely known; however, a broader role in health has been attributed to carotenoids in reducing the risk of several degenerative health problems and certain cancers, in photoprotection of skin, and photoprotection of the eye provided by the carotenoids lutein and zeaxanthin. In a crop such as sweet potato, beta-carotene is the only major carotenoid constituent, so data on overall carotenoid content offers a good nutritional assessment. On the other hand, our results have shown highly diverse carotenoid profiles among different squash cultigens, and many cultigens contain abundant carotenoids not known to provide nutritional benefits. Furthermore, squash are unique in that many varieties are a good source of lutein, typically provided only by green leafy vegetables. Also, a major proportion of the carotenoids in many varieties of squash, including lutein, are molecularly linked to fatty acids by ester bonds (esterified), and these bonds have to be broken prior to absorption of carotenoids into the blood stream. We have developed squash breeding lines in which most of the lutein is non-esterified, and also squash lines in which beta-carotene (non-esterified) is the major carotenoid. These breeding lines are being utilized to develop new hybrid varieties with improved nutritional benefits in terms of carotenoid composition. Our research on eating quality and total carotenoid levels in squash in relation to harvest period and storage time provide base-line information on proper harvest period and storage time for maximizing eating quality and nutrition in squash. This information provides guidelines for growers and consumers of squash that can be disseminated through Cooperative Extension and presentations at grower meetings.
Publications
- Uretsky, J. and J.B. Loy. 2010. Vegetative growth in bush Cucurbita maxima x vine Cucurbita moschata interspecies hybrids, p. 105-108. In: Thies, J.A., S. Kousik and A. Levi (eds.), Proceedings Cucurbitaceae 2010, ASHS Press, Alexandria, VA.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: The key nutritional benefit of winter squash, other than being an excellent carbohydrate source, is its high content of carotenoids. Beta-carotene and alpha-carotene as precursors to vitamin A have long been known to be important for eye function. In addition, however, carotenoids have antioxidant properties, and have been implicated in reducing risk of cardiovascular disease, certain cancers, cataracts and age-related macular degeneration. During the past three years we conducted studies of carotenoid content and profiles in cultigens of Cucurbita maxima and moschata with three major objectives: (1) determine the degree of variability in carotenoid content among different cultivars and breeding lines, (2) determine the effect of premature harvest and storage on carotenoid content, and (3) examine variability in carotenoid profiles among cultigens, with a focus on the most nutritionally important carotenoids - beta-carotene, lutein and zeaxanthin. PARTICIPANTS: Jennifer Noseworthy, doctoral student at University of New Hampshire, is conducting the carotenoid research as part of her dissertation research. Sue Jalbert, a technician in the laboratory of Dr. Joanne Curren-Celentano (co-investigator), is responsible for running carotenoid analyses on HPLC. Seed of the three of the hybrid squash varieties of Cucurbita maxima used in the project were provided by Rupp Seed Company; the varieties were developed at University of New Hampshire. Seed of a fourth commercial variety were provided by Johnny's Selected Seeds, a New England seed company that cooperates with UNH in developing and releasing new varieties of squash and pumpkin. Three of the inbred Cucurbita moschata lines used in the carotenoid study were developed in conjunction with a cooperative breeding project with Hybrid Seeds of New Zealand. TARGET AUDIENCES: Target audiences are consumers of vegetables, produce managers at retail produce outlets, wholesale brokers and distributors of vegetables, vegetable growers, Cooperative Extension Specialists, food scientists, and horticulturists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our spectrophotometric analysis of total carotenoid contents in mesocarp tissue of six C. maxima inbred lines, four C. maxima hybrids, two C. moschata open pollinated cultivars, and five C. moschata inbred lines confirmed visual observations that most modern cultigens of these two species contain relatively high amounts of carotenoids and that selection can be effective in developing breeding lines with exceptionally high levels. We found that carotenoid levels in most cultigens are 30 to 85% higher in squash harvested at maturity (60 days after pollination) than those harvested prematurely at 40 DAP, and in most cultigens, carotenoid levels increase between 20 to 65% with 30 days of storage at 14 C. Nutritional information on vegetable crops is important, both as a marketing tool and to assist consumers in making better dietary choices on food purchases. Squash is one of the leading vegetable crops grown in the Northeast, and is a popular fall vegetable sold at roadside retail markets. Most adult consumers probably associate the deep orange flesh of squash as being a good source of beta-carotene, the major source of provitamin A necessary for good eye health. However, we have found that beta-carotene is not the major carotenoid in the commercial varieties of squash we have evaluated. Moreover, a broader role in health has been attributed to a wider array of carotenoids in reducing the risk of several degenerative health problems such as cardiovascular diseases, certain cancers, and age-related macular degeneration of the retina. Knowledge about the types of carotenoids which comprise popular varieties of squash is not only important to consumers for evaluating health benefits of what they consume, but is also instrumental for breeders to develop new varieties with optimum carotenoid profiles for human health. Our results from examining a limited number of cultigens indicate extensive variability in types of carotenoids in flesh of squash fruit, and a high likelihood that the content of the most important carotenoids implicated in human health - beta-carotene, lutein and zeaxanthin - can be substantially increased through selection in a conventional breeding program. Our research on eating quality and total carotenoid levels in squash in relation to harvest period and storage time provide base-line information on proper harvest period and storage time for optimizing eating quality and nutrition in squash. This information provides for establishment of guidelines on squash quality which can be disseminated to the general public, produce managers, vegetable growers, wholesale brokers and distributors, and professional horticulturists and food scientists through Cooperative Extension, popular articles, newspaper articles, web sites and presentations at grower meetings.
Publications
- Lelley, T., Loy, B. and M. Murkovic. 2010. Breeding Oil Seed Pumpkins. In: Handbook on Plant Breeding, V.4:469-492, Oil Crops, J. Vollman and I Rajcan (eds.), Springer, New York.
|
Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Studies of Cucurbita pepo and Cucurbita maxima squash have shown that proper time of harvest and length of storage are factors paramount to attaining good eating quality and nutrition. However, in cultivars of butternut squash (Cucurbita moschata), one of the most popular types in North America, the major attributes of eating quality, % soluble solids and % dry matter, have not been adequately evaluated nor has the relationship between those parameters of eating quality and the nutritional content in terms of carotenoid levels been investigated. Squash samples from different cultigens (breeding lines, commercial open-pollinated varieties, and F1 hybrids) obtained from replicated field plots were analyzed at four time periods, 40 days post-anthesis (DAP), 60 DAP, 60 DAP + 30 day storage at 15 C, and 60 DAP + 60 day storage. Fruit are considered mature in terms of seed development at about 55 DAP, but appear mature according to size and rind color at 40 DAP. Peak dry matter in squash was reached by 40 DAP, but soluble solids in most cultigens increased progressively from 40 DAP until storage at 60 DAP. In most but not all cultigens an acceptable soluble solids level of 11% or greater was attained by 60 days of storage. Carotenoids were low in all cultigens at immature harvest (40 DAP), and in most cultigens, increased progressively until 60 days of storage. In some cultigens increases in carotenoids during storage could be accounted for by moisture loss and accompanying shrinkage of tissues; however, carotenoid increases in some cultigens from sampling at 40 DAP to harvest at 60 DAP followed by 60 days of storage was more than three-fold, compared to weight losses of only 15 to 17%. In C. maxima cultigens, the predominant carotenoids were either β-carotene or β-carotene and lutein. In most C. moschata cultigens β-carotene was the only major carotenoid, but a few cultigens characterized by mottled green rind had significant amounts of lutein. An interspecies hybrid between C. maxima and C. moschata (NH1937), currently being evaluated for possible release, was found to have a complex carotenoid profile. PARTICIPANTS: Much of the research being reported on this project is being conducted by a doctoral student in Plant Biology, Jennifer Noseworthy. Assistance on breeding work related to the project has been provided by a research technician, Reed Loy, and a summer research assistant, Jacob Uretsky. TARGET AUDIENCES: Information gleaned on squash eating quality and nutritional content is being disseminated to growers with the assistance of Becky Grube, Extension Specialist, through talks at grower meetings, at the UNH Greenhouse Openhouse during the spring, in classes on vegetable production, and recently through an article published in American Vegetable Grower magazine. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
There has been a resurgence in consumer interest in obtaining locally grown produce. To command the premium prices that growers must often charge for locally grown produce, and to continually expand the customer base, local small markets must offer high quality produce. Squash is traditionally a popular food in New England, but fruit offered by local markets exhibit considerable variability in eating and nutritional quality, much of which can be attributed to harvesting fruit at the improper stage and not providing, when necessary, a suitable storage period for optimizing eating quality and nutritional content. Our research on eating quality and carotenoid levels in squash in relation to harvest period and storage time is providing base-line information for developing guidelines for growers and consumers of squash that can be disseminated through Cooperative Extension and presentations at grower meetings. In addition, we are developing nutritional information on popular commercial cultivars and on cultivars either released or being developed at the New Hampshire Agricultural Experiment Station. The knowledge base being acquired on carotenoid profiles in breeding lines is being used for improving the nutritional content of squash.
Publications
- Noseworthy, J. and B. Loy. 2008. Improving eating quality and carotenoid in squash, P. 521-528. In Cucurbitaceae 2008, IXth EUCARPIA Meeting on Genetics and Breeding of Cucurbitaceae, (Pitrat, M, ed.), INRA, Avignon (France), 637 pages.
|
|