Progress 10/01/05 to 09/30/11
Outputs
OUTPUTS: Among vegetables, sweet corn (Zea mays L.) and broccoli (Brassica oleracea L. ssp. italica) are important sources of dietary carotenoids and tocopherols. On an annual per capita consumption basis, sweet corn provides approximately 40% more carotenoids and tocopherols to American diets than broccoli, a vegetable with broad nutritional appeal. There is evidence for a negative correlation between the amounts of these antioxidant compounds consumed and incidence of lung, stomach, cervical, and colorectal cancers, cataract risk and age-related macular degeneration (AMD) and cardiovascular disease. Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose-dependent manner, development of elite sweet corn and broccoli germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. Specific outputs include: 1. Partitioning of variance for tocopherol, carotenoid, and glucosinolate (broccoli only) phytochemical concentrations in 41 and 25 cultivars of sweet corn and broccoli, respective indicated that genetic differences among the genotypes accounted for the largest proportion of the variation (67 and 55% of total phenotypic variation for sweet corn and broccoli, respectively). 2. Identified and mapped over 20 QTL in two segregating F2:3 sweet corn populations that control variation in carotenoid and tocopherol content over three growing seasons. 3. Identified and mapped 2 QTL controlling carotenoid variations, 7 QTL associated with tocopherol content, and 7 QTL regulating aliphatic glucosinolate concentrations in a F2:3 segregating broccoli population. 4. Development of an Agrobacterium tumafaciens-mediated transformation system for corn and broccoli. We are currently in the process of using this transformation system to enhance phytochemical profiles and the nutritional quality of broccoli and corn. PARTICIPANTS: J.A. Juvik, PI. Graduate Students: H.S. Kim (Ph.D.), K.S. Ibrahim (Ph.D.), A.F. Brown (Ph.D.), H.-R. Oh (M.S.), and K. Kobira (M.S.) - all received graduate degree at the University of Illinois in the lab of Dr. Juvik. Collaborators: E.H. Jeffery, C. Yu, J.Y. Kang, and D.W. Kim. TARGET AUDIENCES: This research is targeted to academic vegetable breeders and private seed companies and is designed to provide information on public genotypes that can be used to develop sweet corn and broccoli germplasm with improved nutritional quality. PROJECT MODIFICATIONS: While this project is directed toward work on sweet corn, due to similar project objectives I have included research and outcomes from our work with broccoli (another vegetable with the potential to be genetically modified for enhanced health-promoting bioactivity).
Impacts
Outcomes and impacts include: 1. Our investigations uncovered significant phenotypic variability for all the compounds assayed in both sweet corn and broccoli. The heritability estimates for the primary phytochemicals suggest that currently available commercial and public germplasm can be utilized in breeding programs to develop new sweet corn and broccoli germplasm with elevated carotenoid and tocopherol content. Partitioning of the variance suggests that genetic differences among the sweet corn and broccoli genotypes accounts for the main proportion of variation in phytochemical content, implying that genetic manipulation to enhance corn kernel and broccoli carotenoid and tocopherol content is a feasible breeding objective. Stability differences detected among tested genotypes in this study emphasize the need to survey over multiple environments. Genotypes with enhanced concentrations of health-promoting phytochemicals and superior stability across environments were identified for future breeding efforts. 2. Several target QTL loci with substantial effects on carotenoid, tocopherol, and glucosinolate (broccoli only) content in the sweet corn and broccoli populations were identified for future use in a breeding program. These investigations suggest that corn and broccoli germplasm with improved concentrations of carotenoids, tocopherols, and aliphatic glucosinolates can be developed using conventional breeding protocols. Marker-assisted selection using known marker-QTL associations has facilitated this process. 3. The development of an Agrobacterium tumafaciens-mediated transformation system for corn and broccoli is currently underway to develop transgenics with enhance phytochemical profiles to provide difinitive models to test for health promoting bioactivities of the various corn and broccoli phytochemicals.
Publications
- Kang, J.Y., Ibrahim, K.E., Kim, D.-H., Kang, W.J. and Juvik, J.A. 2006. Genetic and environmental variation of glucosinolate content in Chinese cabbage. HortSci.41: 1382-1385.
- Eberhardt, M., Kobira, K., Keck, A., Juvik, J.A. and Jeffery, E.H. 2005. Correlation analyses of phytochemical composition, chemical, and cellular measures of antioxidant activity of broccoli (Brassica oleracea L. var. italica). J. Agric. Food Chem 53:7421-7431.
- Kobira, K. 2005. Mapping genes associated with antioxidation potential in Brassica oleracea ssp. Italica. M.S. thesis, University of Illinois at Urbana-Champaign. 111 pp.
- Kim, H.S. and Juvik, J.A. 2011. Effect of selenium fertilization and methyl jasmonate treatment on glucosinolate accumulation in broccoli florets. J. Amer. Soc. Hort. Sci.136(4):239-246.
- Kim, H.S. 2010. Functional studies of lignin biosynthesis genes and a putative flowering gene in Miscanthus x giganteus and studies on indolyl glucosinolate biosynthesis and translocation in Brassica oleracea L. Ph.D. Dissertation from the University of Illinois at Urbana-Champaign. 220 pp.
- Ibrahim, K. and Juvik, J.A. 2009. Carotenoid and tocopherol variation in sweet corn and broccoli: Feasibility for improving phytonutrient content. J. Agric. Food Chem. 57:4636-4644.
- Ghimire, B.K., Seong, E.S., Lim, J.D., Heo, K., Kim, M.J., Chung, I.M., Juvik, J.A. and Yu, C.Y. 2008. Over-expression of the g-TMT gene enhances a-tocopherol content in Codonopsis lanceolata. Cell tissue Org Cult. 95: 265-274.
- Ibrahim, K. 2007. Genetic studies on the manipulation of carotenoid and tocopherol content in sweet corn and broccoli. Ph.D. Dissertation, University of Illinois at Urbana-Champaign. 161 pp.
- Brown, A.F., Jeffery, E.H. and Juvik, J.A. 2007. A PCR-based linkage map of broccoli and identification of quantitative trait loci associated with harvest date and head weight. J. Amer. Soc. Hort. Sci. 132: 507-513.
- Oh, H. 2007. Induction of glucosinolate biosynthesis in Brassica vegetables by jasmonate, salicylate, and wounding treatments. M.S. thesis, University of Illinois at Urbana-Champaign. 96 pp.
- Ibrahim, K. and Juvik, J.A. 2006. Partitioning variability in sweet corn and broccoli carotenoid and tocopherol content. HortScience 41:1046.
- Matusheski, N.V., Swarup, R., Juvik, J.A., Mithen, R., Bennett, M. and Jeffery, E.H. 2006. Epithiospecifier protein in broccoli (Brassica oleracea L. ssp. italica): Identification, characterization and physiological significance for the formation of the anticancer agent sulforaphane. J. Agric. Food Chem 54: 2069-2076.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: During the past year and a half we have focused on developing an Agrobacterium tumafaciens mediated transformation system for corn and Miscanthus, a new and dedicated bioenergy crop. In relation to this project we wish to develop a transformation system that will be useful for modifying genotypes of Zea mays L. to enhance kernel phytochemical profiles and the nutritional quality of field and sweet corn. Among vegetables, corn (Zea mays L.) is an important source of dietary carotenoids and tocopherols. Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose dependent manner, genetic modification to develop elite corn and germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. We propose to investigate corn transformation systems and various transgenic approaches to enhance our fundimental understanding of the genetic regulation of the corn carotenoid and tocopherol biosynthetic pathways, not for the development of commercial germplasm. Due to the availability of maize gene sequences associated with the Maizewall data base we first decided to use lignin genes as targets for maize transformation. The lignin biosynthesis C3H, C4H, 4CL, CAD, CCR, and COMT were introduced into the RNAi and antisense constructs, pB7GWIWG2(II) and pB2WG7 (VIB, Leuven, Belgium), using the GATEWAY cloning system. These constructs contained the herbicide resistance gene (bar) as a selection marker. Disarmed Agrobacterium tumerfaciens strain EHA105 was used in a binary vestor system. Using these constructs for transformation of HI-2 maize immature embryos, we have been successful at incorporating the bar gene and herbicide resisance into the maize genome although no transgenic phenotypes were observed among transgenic plants for lignin biosynthesis or concentrations. PARTICIPANTS: This report represents a portion of the Ph.D. reseach program of Dr. Hyoung Soek Kim. Dr. Kim has completed his Ph.D. program at the University of Illinois and assumed a post-doctoral appointment in the lab of Dr. Steven Huber, a USDA scientist in plant molecular biology. TARGET AUDIENCES: This research is targeted to academic plant scientists interested in transgenic modification of plant phytochemical profiles and is designed to investigate genetic approaches to modify sweet corn and broccoli germplasm for improved nutritional quality. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The successfuly incorporation of herbicide resistance into maize by our protocols provides a model system we will use in the future for transgenic modification of the carotenoid and tocopherol biosynthetic pathways in maize kernels.
Publications
- Kim, H.S. 2010. Functional studies of lignin biosynthesis genes and a putative flowering gene in Miscanthus x giganteus and studies on indolyl glucosinolate biosynthesis and translocation in Brassica oleracea L. Ph.D. Dissertation from the University of Illinois at Urbana-Champaign. 220 pp.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Among vegetables, sweet corn (Zea mays L.) and broccoli (Brassica oleracea L. ssp. italica) are important sources of dietary carotenoids and tocopherols. Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose dependent manner, conventional breeding to develop elite sweet corn and broccoli germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. This investigation includes the quantitative analysis of carotenoid and tocopherol content of 41 corn and 24 broccoli genotypes grown in multiple environments (years and seasons in one location) to partition the variation into genetic, environment, and genotype by environment interaction (GxE) components and measure the phenotypic stability of genotypes for these phytochemicals. The primary carotenoids and tocopherols in corn were lutein and γ-tocopherol (65% and 73% of total carotenoid and tocopherol respectively) while β-carotene and α-tocopherol were dominant in broccoli (65% and 79% of total carotenoid and tocopherol respectively). Partitioning of the variance indicated that genetic differences among the genotypes averaged for the primary compounds in corn (lutein, zeaxanthin, and α- and γ-tocopherol) and broccoli (β-carotene, lutein, and α- and γ-tocopherol) accounted for the largest proportion of the variation (67% and 55% of total phenotypic variation averaged across the phytochemicals in sweet corn and broccoli respectively). Stability analysis identified several corn (IL451b sh2 and IL2027-8 sh2) and broccoli (Pirate and Baccus) genotypes with relatively high mean concentrations for the various carotenoids and tocopherols that were comparatively stable across seasons and years. The results of this investigation suggest that sweet corn and broccoli germplasm with substantially improved concentrations of carotenoids and tocopherols can be developed using conventional breeding protocols. PARTICIPANTS: This report represents a portion of the Ph.D. reseach program of Dr. Khalid Ibrahim. Dr. Ibrahim has completed his Ph.D. program at the University of Illinois and assumed a faculty position at the University of Suez in Egypt. TARGET AUDIENCES: This research is targeted to academic vegetable breeders and private seed companies and is designed to provide information on public genotypics that can be used to develop sweet corn and broccoli germplasm with improved nutritional quality. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The quantitative differences in carotenoid and tocopherol content detected in this investigation may reflect allelic variation of gene loci regulating the biosynthesis of these compounds. The results also suggest that currently available commercial and public germplasm can be utilized in breeding programs to develop new sweet corn and broccoli germplasm with elevated carotenoid and tocopherol content. Stability differences detected among genotypes tested in this study emphasizes the need to survey over multiple environments. In conclusion, our results support the feasibility of conventional breeding to increase both carotenoid and tocopherol content in corn and broccoli. Extrapolation of the results obtained in this study to other corn and broccoli genotypes and growing environments is constrained by the fact that this investigation was conducted in a single location over multiple years.
Publications
- Ibrahim, K. and Juvik, J.A. 2009. Carotenoid and tocopherol variation in sweet corn and broccoli: Feasibility for improving phytonutrient content. J. Agric. Food Chem. 57:4636-4644.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Among vegetables, sweet corn is an important source of dietary carotenoids and tocopherols, powerful antioxidants that are believed to promote human health (USDA National Nutrient Database, 2005). Sweet corn kernels contain substantial concentrations of carotenoids and tocopherols such as lutein, zeaxanthin, β-cryptoxanthin, and alpha- and gamma-tocopherol. Sweet corn delivers more carotenoids and tocopherols to American diets than nearly all other vegetables. There is evidence for a negative correlation between the amounts of these antioxidant compounds consumed and incidence of lung, stomach, cervical, and colorectal cancers, cataract risk, and age-related macular degeneration (AMD). Tocopherols also have been associated with reducing the risk of cardiovascular disease by preventing the oxidative modification of low-density lipoproteins (LDL). Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose-dependent manner, development of elite sweet corn germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. To determine the feasibility of designing a breeding program to improve the health-promoting properties of sweet corn an investigation was conducted at the University of Illinois to evaluate the broad-sense heritability of these phytochemicals in two sweet corn populations segregating for genes regulating their concentration in kernels at fresh market harvest (20 days after pollination). These two populations consisted of 214 and 113 F2:3 families from the cross of IL731a su1se1 X W6786 su1Se1 (se1 population) and IL451b sh2 X Ia453 sh2 (sh2 population), planted in two locations over two years in Illinois from which ears were harvested and quantified for carotenoid and tocopherol content by HPLC. The primary carotenoids in both populations were lutein (50% of total carotenoids) and zeaxanthin (44% of total carotenoids) while the primary tocopherol was gamma-tocopherol (80% of total tocopherol). Broad-sense heritability estimates for lutein, zeaxanthin and gamma-tocopherol were 0.68, 0.55, and 0.40 and 0.52, 0.13, and 0.87 in the se1 and sh2 population, respectively. PARTICIPANTS: John A. Juvik, project PI and Khalid Ibrahim, a Ph.D. student at the University of Illinois. TARGET AUDIENCES: Results of this investigation have been reported to members of the ISCDA (International Sweet Corn Development Association), at our annual meeting in Chicago, Illinois and posted on the project's website. This information was also delivered as an invited powerpoint presentation (and posted on the meeting's web site) titled "Genetic and environmental regulation of carotenoid, tocopherol, and glucosinolate form and concentration in sweet corn and broccoli" at the American Chemical Society's annual meeting in Boston in August, 2007. This information is targeted to the sweet corn seed, processing, and production industry and to the public to provide information on the nutritional content of various sweet corn cultivars. The results of this investigation are provided to the International Sweet Corn Development Association (ISCDA) and posted on several websites. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The quantitative differences in carotenoid and tocopherol content detected in this investigation reflect allelic variation of gene loci regulating the biosynthesis of these compounds. The heritability estimates for the primary phytochemicals suggest that currently available commercial and public germplasm can be utilized in breeding programs to develop new sweet corn germplasm with elevated carotenoid and tocopherol content. Relatively high broad sense-heritabilities particularly for lutein and gamma-tocopherol suggest conventional breeding for genotypes with enhanced concentrations of these health-promoting phytochemicals is a feasible objective. In conclusion, our results support the feasibility of genetic manipulation of both carotenoid and tocopherol content in corn.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Among vegetables, sweet corn is an important source of dietary carotenoids and tocopherols, powerful antioxidants that are believed to promote human health (USDA National Nutrient Database, 2005). Sweet corn kernels contain substantial concentrations of carotenoids and tocopherols such as lutein, zeaxanthin, β-cryptoxanthin, and α- and γ-tocopherol. Sweet corn delivers more carotenoids and tocopherols to American diets than nearly all other vegetables. On an annual per capita consumption basis, it provides approximately 40% more carotenoids and tocopherols to American diets than broccoli, a vegetable with broad nutritional appeal. There is evidence for a negative correlation between the amounts of these antioxidant compounds consumed and incidence of lung, stomach, cervical, colorectal cancers, cataract risk and age-related macular degeneration (AMD). Tocopherols also have been associated with reducing the risk of cardiovascular disease by preventing the
oxidative modification of low-density lipoproteins (LDL). Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose dependent manner, development of elite sweet corn germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. To determine the feasibility of designing a breeding program to improve the health-promoting properties of sweet corn an investigation was conducted at the University of Illinois to evaluate the phytochemical stability of different genotypes across environments. Partitioning of the variance of 41 sweet corn genotypes grown in 3 different environments indicated that genetic differences among the genotypes averaged for the primary health-promoting phytochemicals in corn (lutein, zeaxanthin, and α- and γ-tocopherol) accounted for the largest proportion of the variation (67% of total phenotypic variation in sweet corn). Stability analysis identified several
corn (IL451b sh2 and IL2027-8 sh2) genotypes with relatively high mean concentrations for the various carotenoids and tocopherols that were comparatively stable across the three growing environments. Results of this investigation have been reported to members of the ISCDA (International Sweet Corn Development Association), at our annual meeting in Chicago, Illinois and posted on the project's website. At the invitation of the American Chemical Society this information was also delivered as a powerpoint presentation (and posted on the meeting's web site) titled "Genetic and environmental regulation of carotenoid, tocopherol, and glucosinolate form and concentration in sweet corn and broccoli" at the Society's annual meeting in Boston in August, 2007. Several articles from this work are in preparation for submission to scientific journals.
PARTICIPANTS: John A.Juvik, project PI and Khalid Ibrahim, Ph.D. student at the University of Illinois.
TARGET AUDIENCES: This information is targeted to the sweet corn seed, processing and production industry and to the public to provide information on the nutritional content of various sweet corn cultivars. The results of this investigation is provided to the International Sweet Corn Development Association (ISCDA) and posted on several websites.
Impacts
The quantitative differences in carotenoid and tocopherol content detected in this investigation reflect allelic variation of gene loci regulating the biosynthesis of these compounds. The results suggest that currently available commercial and public germplasm can be utilized in breeding programs to develop new sweet corn germplasm with elevated carotenoid and tocopherol content. Stability differences detected among tested genotypes in this study emphasizes the need to survey over multiple environments. Genotypes with enhanced concentrations of health-promoting phytochemicals and superior stability across environments were identified for future breeding efforts. In conclusion, our results support the feasibility of genetic manipulation of both carotenoid and tocopherol content in corn.
Publications
- Ibrahim, K. 2007. Genetic studies on the manipulation of carotenoid and tocopherol content in sweet corn and broccoli. Ph.D. Dissertation, University of Illinois at Urbana-Champaign. 161 pp.
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Progress 01/01/06 to 12/31/06
Outputs
Among vegetables, sweet corn is an important source of dietary carotenoids and tocopherols, powerful antioxidants that are believed to promote human health (USDA National Nutrient Database, 2005). On an annual per capita consumption basis, sweet corn provides approximately 40% more carotenoids and tocopherols to American diets than broccoli, a vegetable with broad nutritional appeal. There is evidence for a negative correlation between the amounts of these antioxidant compounds consumed and incidence of lung, stomach, cervical, colorectal cancers, cataract risk and age-related macular degeneration (AMD). Tocopherols also have been associated with reducing the risk of cardiovascular disease by preventing the oxidative modification of low-density lipoproteins (LDL). Since medical evidence suggests that carotenoid and tocopherol health promoting activity acts in a dose dependent manner, development of elite sweet corn germplasm with enhanced levels of these
phytochemicals will potentially promote health among the consuming public. To determine the feasibility of designing a breeding program to improve the health-promoting properties of sweet corn an investigation was conducted to partition phenotypic variance for carotenoid and tocopherol content into its component sources (genotypic, environmental and GXE interaction). Of the total phenotypic variation in carotenoid and tocopherol content (for lutein, zeaxanthin, and a-and g-tocopherol) among kernels from 41 different corn lines harvested at 20 days after pollination over three growing seasons, approximately 68% could be attributed to genetic differences among the genotypes with 25% due to G x E. The seasonal (environmental) variation was a relatively minor factor accounting for only 5.6% of the variation averaged across the four phytochemicals. We have also completed a five-year project to identify and map key genes in two segregating sweet corn populations that control variation in
carotenoid and tocopherol content over three growing seasons. These two populations (IL731a su1se1 X W6786 su1Se1 consisting of 196 F2:3 families and IL451b sh2 X Ia453 sh2 with 117 F2:3 families) have been mapped to near saturation with segregating RFLP markers. Ears from 20 DAP ears from the families in these mapping populations were quantitatively assayed for antioxidants by HPLC and the resulting data analyzed in order to identify RFLP loci linked to QTL influencing this trait. On a concentration basis lutein, zeaxanthin, and a and g tocopherol were the dominant chemical forms. For the carotenoids, QTL analysis identified 15 loci (12 in the se1 and 3 in the sh2 population) with LOD scores greater than 3.0 accounting from 7-30% of the phenotypic variation. The se1 locus near umc36a on chromosome 2 was strongly associated with carotenoid content as has been previously reported. A locus near umc160 and bnl9.08 on chromosome 8 was also was linked to a QTL that influenced carotenoid
content possibly in both populations. For the tocopherols 9 distinct QTL were identified (6 in the se1 and 3 in the sh2 population) accounting from 7-18% of the phenotypic variation.
Impacts
This investigation uncovered significant phenotypic variability for all the compounds assayed. Partitioning of the variance suggests that genetic differences among the sweet corn genotypes accounts for the main proportion of variation in antioxidant phytochemical content, implying that genetic manipulation to enhance corn kernel carotenoid and tocopherol content is a feasible breeding objective. Extrapolation of these findings to other corn genotypes and environments is constrained by the fact that these investigations were conducted in a single location over three years. Several target QTL loci with substantial effects on carotenoid and tocopherol content in the two sweet corn populations were identified for future use in a breeding program. These investigations suggest that corn germplasm with improved concentrations of carotenoids and tocopherols can be developed using conventional breeding protocols. Marker-assisted selection using known marker-QTL associations
would facilitate this process.
Publications
- Ibrahim, K. and Juvik, J.A. 2006. Partitioning variability in sweet corn and broccoli carotenoid and tocopherol content. HortScience 41:1046.
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