Advertisement

Plant Molecular Biology

, Volume 53, Issue 1–2, pp 75–86 | Cite as

Post-transcriptional regulation of expression of the Bronze2 gene of Zea mays L.

  • Claudio F. Pairoba
  • Virginia Walbot
Article

Abstract

The glutathione S- transferase encoded by Bronze2 performs the last genetically defined step in maize anthocyanin biosynthesis, being required for pigment sequestration into vacuoles. The Bz2 primary transcript contains a single intron; in maize leaves both spliced and unspliced Bz2 transcripts are usually present and are predicted to encode 26 and 14 kDa proteins, respectively. To increase understanding of the role and regulation of Bz2 transcript splicing, we examined Bz2 expression during development in transgenic maize plants expressing a 35S:Bz2 (35S:mycBz2i) gene and, by transient expression analysis, in Black Mexican Sweet maize protoplasts. We show here that the gene is expressed in diverse tissues that lack functional copies of one or both transcription factors regulating anthocyanin synthesis, that transcript levels are much higher when the R/B plus C1/Pl transcription factors are present, and that the splicing decision depends on local sequence context. The predicted 14 kDa protein was never detected indicating that unspliced transcripts are likely to be non-coding. The native 26 kDa BZ2 protein is loosely membrane-bound, but it was detectable only in tissues accumulating anthocyanin. Consequently, BZ2 accumulation appears to be limited by stringent post-transcriptional regulation.

anthocyanin flavonoids RNA splicing transgenic plants 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Alfenito, M.R., Souer, E., Goodman, C.D., Buell, R., Mol, J., Koes, R. and Walbot, V. 1998. Functional complementation of anthocyanin sequestration in the vacuole by widely divergent glutathione S-transferases. Plant Cell 10: 1135–1149.Google Scholar
  2. Bodeau, J.P. and Walbot, V. 1992. Regulated transcription of the maize Bronze2 promoter in electroporated protoplasts requires the C1 and R gene products. Mol. Gen. Genet. 233: 379–387.Google Scholar
  3. Casati, P. and Walbot, V. 2003. Gene expression profiling in response to ultraviolet radiation in maize genotypes with varying flavonoid content. Plant Physiol. 132: 1739–1754.Google Scholar
  4. Cobbett, C.S., May, M.J., Howden, R. and Rolls, B. 1998. The glutathione-deficient, cadmium-sensitive mutant, cad2-1, of Arabidopsis thaliana is deficient in gamma-glutamylcysteine synthetase. Plant J. 16: 73–78.Google Scholar
  5. Coe, E.H., Hoisington, D.A. and Neuffer, M.G. 1988. The genetics of corn. In: G.F. Sprague and J. Dudley (Eds.) Corn and Corn Improvement, American Society of Agronomy, Madison, WI, pp. 81–258.Google Scholar
  6. Dixon, D.P., Lapthorn, A. and Edwards, R. 2002. Plant glutathione transferases. Genome Biol. 3, rev. 3004.1–3004.10.Google Scholar
  7. Edwards, R., Dixon, D.P. and Walbot, V. 2000. Plant glutathione S-transferases: enzymes with multiple functions in sickness and in health. Trends Plant Sci. 5: 193–198.Google Scholar
  8. Fisher, R.F. and Long, S.R. 1992. Rhizobium-plant signal exchange. Nature 357: 655–660.Google Scholar
  9. Grotewold, E., Sainz, M.B., Tagliani, L., Hernandez, J.M., Bowen, B. and Chandler, V.L. 2000. Identification of the residues in the Myb domain of maize C1 that specify the interaction with the bHLH cofactor R. Proc. Natl. Acad. Sci. USA 97: 13579–13584.Google Scholar
  10. Harborne, J.B. and Self, R. 1987. Malonated cyaniding 3-glucosides in Zea mays and other grasses. Phytochemistry 26: 2417–2418.Google Scholar
  11. Ishikawa, T. 1992. The ATP-dependent glutathione S-conjugate export pump. Trends Biochem. Sci. 17: 463–468.Google Scholar
  12. Laemmli, U.K. 1970. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227: 680–685.Google Scholar
  13. Levine, A.R., Tenhaken, R., Dixon, R. and Lamb, C. 1994. H2O2 from the oxidative burst orchestrates the plant hypersensitive disease resistance response. Cell 79: 583–593.Google Scholar
  14. Li, Z.-S., Zhao, Y. and Rea, P.E. 1995. Magnesium adenosine 5′-triphosphate-energized transport of glutathione S-conjugates by plant vacuolar membrane vesicles. Plant Physiol. 107: 1257–1268.Google Scholar
  15. Marrs, K.A. 1996. The functions and regulation of glutathione S transferases in plants. Annu. Rev. Plant Physiol. Plant Mol. Biol. 47: 127–158.Google Scholar
  16. Marrs, K.A. and Walbot, V. 1997. Expression and RNA splicing of the maize glutathione S-transferase Bronze2 gene is regulated by cadmium and other stresses. Plant Physiol. 113: 93–102.Google Scholar
  17. Marrs, K., Alfenito, M.R., Lloyd, A.M. and Walbot, V. 1995. A glutathione S- transferase involved in vacuolar transfer encoded by the maize gene Bronze2. Nature 375: 397–400.Google Scholar
  18. McLaughlin M. and Walbot, V. 1987. Cloning of a transposable Bz2 allele of maize by transposon tagging and differential hybridization. Genetics 117: 771–776.Google Scholar
  19. Mo, Y., Nagel, C. and Taylor, L. 1992. Biochemical complementation of chalcone synthase mutants defines a role for flavonols in functional pollen. Proc. Natl. Acad. Sci. USA 89: 7213–7217.Google Scholar
  20. Mol J., Grotewold, E. and Koes, R. 1998. AUTHOR: PLEASE PROVIDE PAPER TITLE. Trends Plant Sci 3: 212–217.Google Scholar
  21. Mozer, T.J., Tiemeier, D.C. and Jaworski, E.G. 1983. Purification and characterization of corn glutathione S-transferases. Biochemistry 22: 1068–1072.Google Scholar
  22. Mueller, L.A., Goodman, C.D., Silady, R.A. and Walbot, V. 2000. AN9, a Petunia glutathione S-transferase required for anthocyanin sequestration, is a flavonoid-binding protein. Plant Physiol. 123: 1561–1570.Google Scholar
  23. Nash, J. and Walbot, V. 1992. Bronze-2 gene expression and intron splicing patterns in cells and tissues of Zea mays L. Plant Physiol. 100: 464–471.Google Scholar
  24. Nash, J., Luehrsen, K.R. and Walbot, V. 1990. Bronze-2 gene of maize: reconstruction of a wild-type allele and analysis of transcription and splicing. Plant Cell 2: 1039–1049.Google Scholar
  25. Plewa, M.J. and Wagner, E.D. 1993. Activation of promutagens by plants. Annu. Rev. Genet. 27: 93–113.Google Scholar
  26. Raizada, M.N. and Walbot, V. 2000. The late developmental pattern of Mu transposon excision is conferred by a cauliflower mosaic virus 35S-driven MURA cDNA in transgenic maize. Plant Cell 12: 5–22.Google Scholar
  27. Rea, P. 1999. MRP subfamily ABC transporters from plants and yeast. J. Exp. Bot. 50: 895–913.Google Scholar
  28. Sandermann, H. 1992. Plant metabolism of xenobiotics. Trends Biochem. Sci. 17: 82–84.Google Scholar
  29. Saslowsky, D. and Winkel-Shirley, B. 2001. Localization of flavonoid enzymes in Arabidopsis roots. Plant J. 27: 37–48.Google Scholar
  30. Stapleton, A. and Walbot, V. 1994. Flavonoids can protect maize DNA from UV damage. Plant Physiol. 105: 881–889.Google Scholar
  31. Walbot, V., Benito, M.-I., Bodeau, J. and Nash, J. 1994. Abscisic acid induces pink pigmentation in maize aleurone tissue in the absence of Bronze2. Maydica 39: 19–28.Google Scholar
  32. Winkel-Shirley, B. 2001a. Flavonoid biosynthesis: a colorful model for genetics, biochemistry, cell biology and biotechnology. Plant Physiol. 126: 485–493.Google Scholar
  33. Winkel-Shirley, B. 2001b. It takes a garden. How work on diverse plant species has contributed to an understanding of flavonoid metabolism. Plant Physiol. 127: 1399–1404.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  1. 1.Department of Biological SciencesStanford UniversityStanfordUSA

Personalised recommendations