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I.L. Goldman

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I.L. Goldman

Plants are the foundation for a significant part of human medicine and for many of the most widely used drugs designed to prevent, treat, and cure disease. Folkloric information concerning traditional remedies for disease has had inestimable value in establishing familial and cultural linkages. During the 20th century, modern medical science in the U.S. and other developed countries ushered in a new era focused on synthetic medicines. Even though many of these compounds were based on natural compounds found in plants, the drive towards synthetic pharmaceuticals created a knowledge gap concerning the health functionality of plants, crops, and food. Paralleling this development, biochemists and nutritional scientists pioneered the discovery of vitamins during the early decades of the 20th century. This research paved the way for dietary guidelines based on empirical data collected from animal feeding trials and set the stage for the current emphasis on phytonutrients. Three primary stages characterize the use of fruits and vegetable in human health. The first stage concerns the observation that many fruit and vegetable crops were originally domesticated for their medicinal properties. Making their way into the diet for this purpose, fruit and vegetable crops remained on the fringe from a culinary point of view. The second stage began when the role of vitamins became more widely understood, and fruit and vegetable plants were quickly recognized as a rich source of certain vitamins, minerals, and fiber. At this point, they became more than just an afterthought in the diet of most U.S. citizens. Cartoon icons such as Popeye made the case for the health functionality of leafy greens, while parents schooled their children on the virtues of carrots (Daucus carota), broccoli (Brassica oleracea), and green beans (Phaseolus vulgaris). This renaissance resulted in large increases in fresh fruit and vegetable consumption across the country, a trend that continues to this day. The third phase can be characterized by the recognition that fruit and vegetable crops contain compounds that have the potential to influence health beyond nutritional value. These so-called functional foods figure prominently in the dietary recommendations developed during the last decades of the 20th century. In recent years, surveys suggest nearly two-thirds of grocery shoppers purchase food specifically to reduce the risk of, or manage a specific health condition. Evidence abounds that consumers, including Baby Boomers, choose foods for specific health benefits, such as the antioxidant potential of vegetables, suggesting high levels of nutritional literacy. Clinical and in vitro data have, to some degree, supported the claims that certain foods have the potential to deter disease, however much research remains to be conducted in order to definitively answer specific dietary-based questions about food and health.

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I.L. Goldman

Wisconsin Fast Plants are rapid-cycling versions of various Brassica species amenable to a variety of genetic studies due to their short life cycle and ease of handling. I have recently developed a model system using Brassica rapa L. Fast Plants for teaching the cyclical selection process known as recurrent selection in the context of a course on plant breeding. The system allows for up to three cycles of recurrent selection during a 15-week semester and enables students to gain experience in planting, selection, pollination, and seed harvest during each cycle. Fourteen cycles of replicated, recurrent mass selection for high (H) and low (L) levels of anthocyanin pigment expression in hypocotyl tissue were practiced by students in Horticulture 502 during a period of four semesters. In addition to bi-directional selection; replicated unselected (D) control populations were maintained forcomparative purposes. Over 14 cycles, highly significant gains and losses in hypocotyl pigment production were realized for H and L populations, respectively. Plants in D populations showed no directional response to random selection and therefore did not exhibit genetic drift. Plants in H populations exhibited production of anthocyanin pigment in organs other than hypocotyls, suggesting selection goals could be modified to include pigmentation of specific organs or whole plants. Results from this selection program suggest significant gains from recurrent selection can be visualized through student-based selection activities in the classroom.

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I.L. Goldman

Carrots contribute ≈14% of the total Vitamin A to the human diet in the United States due to the presence of the provitamin A carotenoids α- and β-carotene. We have described a recessive gene (rp) that inhibits carotenoid biosynthesis in carrot by 93%, resulting in whitish-yellow roots. The rp mutation is also associated with relatively high levels of a tocopherol (Vitamin E, 0.61±0.15 mg α-tocopherol/100 g FW). Vitamin E is a powerful antioxidant that must be obtained from the diet. The biosynthesis of a tocopherol in carrot has not been studied in any detail; however, the rp gene may provide clues as to its mechanism. The production of carotenoids and tocopherols is biosynthetically linked by their common precursor, geranylgeranyl diphosphate (GGDP). GGDP is converted into phytoene by phytoene desaturase to produce carotenoids and combined with homogentisic acid to produce tocopherols. Carotenoid and tocopherol profiles for various carrot genotypes are presented alongside a model describing the potential relationship between root carotenoids and tocopherols in carrot. The presence of significant amounts of tocopherols in carrot could significantly raise the nutritional profile of this vegetable.

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I.L. Goldman

Pigments in orange carrot tissue, such alpha and beta carotene, are important vitamins in the human diet. Previously identified white or nonpigmented carrot roots, such as those from wild carrot and white derivatives of yellow or orange types, are dominant to the production of pigment, which is recessive. A nonpigmented carrot root was discovered during routine propagation of the inbred line W266 in 1992. Subsequent segregation analysis in the F2 and BC1 generations in three genetic backgrounds demonstrated the lack of pigmentation is due to a single recessive gene (reduced-pigment: rp). Total carotenoid content was reduced 92% in the roots of rprp genotypes compared to RPRP genotypes, however there were no differences in carotenoid content in leaves. Plants carrying rprp also exhibit white-speckled leaves during early stages of development, suggesting rp has an effect on leaf chlorophyll content. This character may prove useful in dissecting the complex inheritance of carotenoids in carrot.

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I.L. Goldman

Few genes have been identified in red beet. A spontaneously occurring dwarf mutant was identified in the late 1970s and again in 1994 in several breeding populations. Mutant plants are characterized by extreme dwarfing of both root and shoot. Young leaves are narrow, thin and strap-like while older leaves are thicker and deeply veined. The shoot axis forms a compressed rosette. Neither the shoot axis nor the root axis of field-grown plants exceeds 3 cm in height. Genetic analysis of F2 and backcross populations revealed the dwarf phenotype is conditioned by a single recessive gene. Several experiments were conducted to determine if the dwarf phenotype was due to a lack of gibberellic acid (GA) production. Exogenous application of GA3 at concentrations ranging from 1 to 1000 ppm on dwarf plants a) following seeding and b) during reproductive growth revealed a linear increase in plant height. Control dwarf plants receiving a water-only treatment were 18% as tall as plants receiving regular application of 1000 ppm GA3. A wild-type phenotype during reproductive growth was recoverable following regular GA3 application.

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I.L. Goldman

Onion consumption promotes cardiovascular health by inhibiting platelet activity. Bulbs are the only onion plant organ thus far examined for antiplatelet activity. The inbred line W420B was grown in replicated field trials at four United States locations in 1994. At bulb maturity, samples from each plot were tested for antiplatelet activity using human blood plasma. The remaining portion of the bulbs from each plot was stored, vernalized, and planted in a breeding nursery in 1995. Umbels were excised from 20 randomly selected plants when >50% of the flowers had opened and tested for antiplatelet activity. Inducement of antiplatelet activity was 336% higher by onion umbels than by bulbs. This finding indicates onion umbels are a more potent source of antiplatelet activity than onion bulbs. In addition, these data suggest that onion umbels may be a richer source of bioactive organosulfur compounds in onion tissue.