2007 Annual Report
Identifying Metal-Related Genes That are Active in Rice Leaves: Rice is an important food crop, but it is a poor source of essential micronutrient metals such as iron and zinc. Children's Nutrition Research Center researchers are interested in improving the nutritional value of rice for human consumption, through plant breeding or biotechnology, but to do this we need more information on the genes and mechanisms within plants that help to move iron and zinc from leaves to developing seeds. In this study, our lab developed a special membrane that allows us to simultaneously measure the levels of 36 genes in rice. The genes chosen were ones that encode for proteins that are involved in the movement or storage of zinc or iron. We studied these levels in leaves of four diverse rice cultivars, which show differing concentrations of iron or zinc in their seeds; of the 36 genes studied, our membrane identified 12 genes that were active in rice leaves of all four cultivars. These results are helping us to determine which genes are important in the distribution of iron and zinc within the plant, and will enable plant breeders to develop more nutritious rice cultivars. [NP 107, Component 2 Bioavailability of Nutrients and Food Components] (CNRC Project 1)
Differences in Pathways of Calcium Oxalate Formation: Researchers at the Children's Nutrition Research Center at Houston, TX, discovered the existence of independent pathways of calcium oxalate formation in Medicago truncatula. CNRC researchers crossed different calcium oxalate mutants that were blocked at different sites in the calcium oxalate formation pathway, to reveal differences in incrustation and prismatic calcium oxalate crystal formation. This finding can have a significant impact on designing strategies to improve the nutritional quality and production of plant foods, since we have shown that calcium oxalate formation can have a negative impact on calcium bioavailability for nutritional absorption; however, calcium oxalate also increases the plant’s resistance to insects. Therefore, efforts to manipulate the process of crystal formation have to take these two contrasting impacts into account. The presence of different pathways of calcium oxalate formation may allow easier implementation of strategies to increase nutritional quality while maintaining insect resistance. [NP 107, Component 2 Bioavailability of Nutrients and Food Components] (CNRC Project 3)
Farnham, M.W., Hale, A.L., Grusak, M.A., Finley, J.W. 2007. Genotypic and environmental effects on selenium concentration of broccoli heads grown without supplemental selenium fertilizer. Plant Breeding. 126:195-200.
Gallardo, K., Lesignor, C., Darmency, M., Burstin, J., Thompson, R., Rochat, C., Boutin, J., Kuester, H., Buitink, J., Leprince, O., Limami, A., Grusak, M.A. 2006. Seed biology of Medicago truncatula. In: Mathesius, U., editor. The Medicago truncatula Handbook. Ardmore, OK: The Samuel Roberts Noble Foundation. Available: http://www.noble.org/MedicagoHandbook/
Narayanan, N.N., Vasconcelos, M.W., Grusak, M.A. 2007. Expression profiling of Oryza sativa metal homeostasis genes in different rice cultivars using a cDNA macroarray. Plant Physiology and Biochemistry. 45(5):277-286.
Kim, C.K., Han, J-S., Lee, H-S., Oh, J-Y., Shigaki, T., Park, S.H., Hirschi, K. 2006. Expression of an "Arabidopsis CAX2" variant in potato tubers increases calcium levels with no accumulation of manganese. Plant Cell Reports. 25(11):1226-1232.
Shigaki, T., Rees, I., Nakhleh, L., Hirschi, K.D. 2006. Identification of three distinct phylogenetic groups of CAX Cation/Proton Antiporters. Journal of Molecular Evolution. 63(6):815-825.
Shigaki, T., Hirschi, K.D. 2006. Diverse functions and molecular properties emerging for CAX Cation/H+ exchangers in plants. Plant Biology. 8(4):419-429.
Park, S., Li, J., Pittman, J.K., Berkowitz, G.A., Yang, H., Undurraga, S., Morris, J., Hirschi, K.D., Gaxiola, R.A. 2005. Up-regulation of a H(+)-pyrophosphatase (H(+)-PPase) as a strategy to engineer drought-resistant crop plants. Proceedings of the National Academy of Sciences. 102(52):18830-18835.
Grusak, M.A. 2005. Legumes. In: Caballero, B., Allen, L., Prentice, A., editors. Encyclopedia of Human Nutrition. 2nd edition. New York, NY: Elsevier Academic Press. p. 120-126.
Bock, K.W., Honys, D., Ward, J.M., Padmanaban, S., Nawrocki, E.P., Hirschi, K.D., Twell, D., Sze, H. 2006. Integrating membrane transport with male gametophyte development and function through transcriptomics(1)[W]. Plant Physiology. 140(4):1151-1168.
Nakata, P.A., McConn, M.M. 2007. Calcium oxalate content affects the nutritional availability of calcium from Medicago truncatula leaves. Plant Science. 172(5):958-961.
Morris, J., Nakata, P.A., McConn, M., Brock, A., Hirschi, K.D. 2007. Increased calcium bioavailability in mice fed genetically engineered plants lacking calcium oxalate. Plant Molecular Biology. 64(5):613-618.
Nakata, P.A., McConn, M. 2007. Genetic evidence for differences in the pathways of druse and prismatic calcium oxalate crystal formation in Medicago truncatula. Functional Plant Biology. 34:332-338.
Nakata, P.A., McConn, M. 2007. Isolated medicago truncatula mutants with increased calcium oxalate crystal accumulation have decreased ascorbic acid levels. Plant Physiology and Biochemistry. 45:216-220.
Cheng, N-H., Liu, J-Z., Brock, A., Nelson, R.S., Hirschi, K.D. 2006. AtGRXcp, an "Arabidopsis" chloroplastic glutaredoxin, is critical for protection against protein oxidative damage. Journal of Biological Chemistry. 281(36):26280-26288.
Cheng, N-H. 2006. Using yeast two hybrid system to study protein-protein interactions. In: Peng, X.X., editor. A Practical Approach: Plant Gene Engineering. Beijing, China: Chemical Industry Publishing House. p. 161-174.
Koren'kov, V., Park, S., Cheng, N.-H., Sreevidya, C., Lachmansingh, J., Morris, J., Hirschi, K., Wagner, G.J. 2007. Enchanced Cd[2+]-selective root-tonoplast-transport in tobaccos expressing Arabidopsis cation exchangers. Planta. 225(2):403-411.
Wood, J.A., Grusak, M.A. 2007. Nutritional value of chickpea. In: Yadav, S.S., Redden, R.J., Chen, W., Sharma, B., editors. Chickpea Breeding and Management. Oxfordshire, UK: CAB International. p. 101-142.
Vasconcelos, M., Eckert, H., Arahana, V., Graef, G., Grusak, M.A., Clemente, T. 2006. Molecular and phenotypic characterization of transgenic soybean expressing the arabidopsis ferric chelate reductase gene, FRO2. Planta. 224:1116-1128.