High Lysine and High Tryptophan Transgenic Maize Resulting from the Reduction of Both 19- and 22-kD α-zeins
The major maize seed storage proteins, zeins, are deficient in lysine and tryptophan content, which contribute to the poor nutritional quality of corn. Whether through the identification of mutations or genetic engineering, kernels with reduced levels of zein proteins have been shown to have increased levels of lysine and tryptophan. It has been hypothesized that these increases are due to the reduction of lysine-poor zeins and a pleiotropic increase in the lysine-rich non-zein proteins. By transforming maize with constructs expressing chimeric double-stranded RNA, kernels derived from stable transgenic plants displayed significant declines in the accumulation of both 19- and 22-kD α-zeins, which resulted in higher lysine and tryptophan content than previously reported for kernels with reduced zein levels. The observation that lysine and tryptophan content is correlated with the protein levels measured in transgenic maize kernels is consistent with the hypothesis that a pleiotropic increase in non-zein proteins is contributing to an improved amino acid balance. In addition, a large increase in accumulation of free amino acids, consisting predominantly of asparagine, asparate and glutamate, was observed in the zein reduction kernels.
Keywordsgene suppression high lysine high tryptophan maize nutritional quality maize quality trait zein reduction
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- Armstrong, C.L. and Rout, J.R. 2001. A novel Agrobacterium-mediated plant transformation method. WO Patent 0109302Google Scholar
- Coleman, C.E., Larkins, B.A. 1999
The prolamins of maizeShewry, P.R.Casey, R. eds. Seed ProteinsKluwer Academic PublishersThe Netherlands109139Google Scholar
- Dellaporta, S. 1994
Plant DNA miniprep and microprepFreeling, M.Walbot, V. eds. The Maize HandbookSpringer-VerlagNew York522525Google Scholar
- Dembinski, E., Bany, S., Raczynska-Bojanowska, K. 1995Asparagine and glutamine in the leaves of high and low protein maizeActa Physiol. Plant17361365Google Scholar
- Dyer, D.J., Feng, P. 1997NIR destined to be major analytical influenceFeedstuffs691625Google Scholar
- Glassman, K.F., Gordon-Kamm, W.J., Kinney, K.J., Lowe, K.S., Nichols, S.E. and Stecca, K.L. 2003. Recombinant constructs and their use in reducing gene expression. US Pat. Appl. Pub. No. US 2003/0036197 A1Google Scholar
- Nelson, O.E., Mertz, E.T., Bates, L.S. 1965Second mutant gene affecting the amino acid pattern of maize endosperm proteinsScience15014691470Google Scholar
- Prasanna, B.M., Vasal, S.K., Kassahun, B., Singh, N.N. 2001Quality protein maizeCurr. Sci.8113081319Google Scholar
- Puckett, J.L., Kriz, A.L. 1991Globulin gene expression in opaque-2 and floury-2 mutant maize embryosMaydica36161167Google Scholar
- Wesley, S.V., Helliwell, C.A., Smith, N.A., Wang, M.-B., Rouse, D.T., Liu, Q., Gooding, P.S., Singh, S.P., Abbott, D., Stoutjesdijk, P.A., Robinson, S.P., Gleave, A.P., Green, A.G., Waterhouse, P.M. 2001Construct design for efficient, effective and high-throughput gene silencing in plantsPlant J.27581590PubMedCrossRefGoogle Scholar