American Journal of Potato Research

, Volume 88, Issue 6, pp 485–492 | Cite as

Structure of Two Solanum tuberosum Steroidal Glycoalkaloid Glycosyltransferase Genes and Expression of their Promoters in Transgenic Potatoes

  • Kent F. McCue
  • David R. Rockhold
  • Alyssa Chhan
  • William R. Belknap


The Sgt2 gene in potato encodes a solanidine glucosyltransferase and is present as two distinct alleles expressed in cultivated potatoes. Promoter regions of both steroidal glycoalkaloid biosynthetic gene alleles, Sgt2.1 and Sgt2.2, were isolated from Solanum tuberosum cv. Russet Burbank genomic DNA. The genomic sequences of Sgt2.1 and Sgt2.2 were isolated by PCR amplification using a conserved region of Sgt2 and artificial upstream primers. The longest sequences for each allele were used to create β-glucuronidase (GUS) reporter gene fusions. Fusion constructs were mobilized into stable transgenic lines for analysis of promoter expression in leaves and tubers under control and wounded conditions. S. tuberosum promoters from Sgt2.1 and from Sgt2.1 produced GUS activity in transgenic potato leaves and tubers comparable to GUS activity produced by the CaMV35S promoter. The CaMV35S promoter is a strong promoter frequently used in plant biotechnology. Both Sgt2 promoters exhibited activities similar to the CaMV35S promoter in tubers and lower relative activities in leaves. On average the Sgt2.2 promoter exhibited higher activity in both leaves and tubers relative to the Sgt2.1. There was no consistent effect of wounding on GUS activity from the Sgt2.2 promoter in leaves or tubers. The Sgt2.1 promoter supported higher transgene activity in tubers versus leaves and exhibited small but consistent increases in response to wounding in tubers only. This may be due to the presence of a MITE sequence in the Sgt2.1 promoter.


Transgenic Sgt2 Glucosyltransferase Leaf Tuber GUS expression 


El gen Sgt2 codifica para una solanidina-glucosiltransferasa y está presente como dos alelos distintos expresados en papas cultivadas. Las regiones promotoras de estos dos genes alelos biosinteticos de glicoalcaloides steroidales, Sgt2.1 y Sgt2.2, se aislaron de ADN genómico de Solanum tuberosum cv. Russet Burbank. Se aislaron las secuencias genómicas de Sgt2.1 y Sgt2.2 mediante amplificación por PCR usando una región conservada de Sgt2 y con iniciadores artificiales de partes superiores. Se usaron las secuencias más largas para cada alelo para crear fusiones de genes reporteros de β-glucuronidasa (GUS). Las fusiones generadas se movilizaron hacia líneas transgénicas estables para el análisis de la expresión del promotor en hojas y tubérculos bajo condiciones de control y de heridas. Los promotores de S. tuberosum de Sgt2.1 y de Sgt2.2 produjeron actividad GUS en hojas de papa transgénica y en tubérculos comparable con la actividad GUS producida por el promotor CaMV35S. Éste es un fuerte promotor que se usa frecuentemente en biotecnología de plantas. Los dos promotores de Sgt2 exhibieron actividades similares a las del promotor CaMV35S en tubérculos y actividades relativas más bajas en hojas. En promedio, el promotor Sgt2.2 exhibió mayor actividad tanto en hojas como en tubérculos en relación con el Sgt2.1. No hubo efecto consistente de heridas en la actividad de GUS del promotor Sgt2.2 en hojas o tubérculos. El promotor Sgt2.1 resistió más alta actividad transgénica en tubérculos contra hojas, y mostró aumentos pequeños pero consistentes en respuesta a heridas solamente en tubérculos. Esto pudo deberse a la presencia de una secuencia MITE en el promotor Sgt2.1.

Supplementary material

12230_2011_9215_MOESM1_ESM.docx (19 kb)
Supplemental Fig. 1(DOCX 19 kb)
12230_2011_9215_MOESM2_ESM.docx (46 kb)
Supplemental Fig. 2(DOCX 46 kb)
12230_2011_9215_MOESM3_ESM.docx (18 kb)
Supplemental Fig. 3(DOCX 17 kb)


  1. Akeley, R.V., W.R. Mills, C.E. Cunningham, and J. Watts. 1968. Lenape: a new potato variety high in solids and chipping quality. American Potato Journal 45: 142–151.CrossRefGoogle Scholar
  2. Altschul, S.F., W. Gish, W. Miller, E.W. Myers, and D.J. Lipman. 1990. Basic local alignment search tool. Journal of Molecular Biology 215(3): 403–410.PubMedGoogle Scholar
  3. Belknap, W.R., D.R. Rockhold, and K.F. McCue. 2008. pBINPLUS/ARS: An improved plant transformation vector based on pBINPLUS. Biotechniques 44(6): 753–756.PubMedCrossRefGoogle Scholar
  4. Dale, M., D. Griffiths, H. Bain, and D. Todd. 1993. Glycoalkaloid increase in Solanum tuberosum on exposure to light. Annals of Applied Biology 123: 411–418.CrossRefGoogle Scholar
  5. Garbarino, J.E., and W.R. Belknap. 1994. Isolation of a ubiquitin-ribosomal protein gene (ubi3) from potato and expression of its promoter in transgenic plants. Plant Molecular Biology 24(1): 119–127.PubMedCrossRefGoogle Scholar
  6. Garbarino, J.E., T. Oosumi, and W.R. Belknap. 1995. Isolation of a polyubiquitin promoter and its expression in transgenic potato plants. Plant Physiology 109(4): 1371–1378.PubMedCrossRefGoogle Scholar
  7. Jefferson, R.A., S.M. Burgess, and D. Hirsh. 1986. beta-Glucuronidase from Escherichia coli as a gene-fusion marker. Proceedings of the National Academy of Sciences USA 83(22): 8447–8451.CrossRefGoogle Scholar
  8. Krits, P., E. Fogelman, and I. Ginzberg. 2007. Potato steroidal glycoalkaloid levels and the expression of key isoprenoid metabolic genes. Planta 227(1): 143–150.PubMedCrossRefGoogle Scholar
  9. McCue, K.F. 2009. Potato glycoalkaloids, past present and future. Fruit, Vegetable and Cereal Science and Biotechnology 3(Special Issue 1): 7.Google Scholar
  10. McCue, K.F., L.V.T. Shepherd, P.V. Allen, M.M. Maccree, D.R. Rockhold, D. Corsini, H. Davies, and W.R. Belknap. 2005. Metabolic compensation of steroidal glycoalkaloid biosynthesis in transgenic potato tubers: using reverse genetics to confirm the in vivo enzyme function of a steroidal alkaloid galactosyltransferase. Plant Science (Shannon) 168: 267–273.CrossRefGoogle Scholar
  11. McCue, K.F., P.V. Allen, L.V. Shepherd, A. Blake, J. Whitworth, M.M. Maccree, D.R. Rockhold, D. Stewart, H.V. Davies, and W.R. Belknap. 2006. The primary in vivo steroidal alkaloid glucosyltransferase from potato. Phytochemistry 67(15): 1590–1597.PubMedCrossRefGoogle Scholar
  12. McCue, K.F., P.V. Allen, L.V. Shepherd, A. Blake, M.M. Maccree, D.R. Rockhold, R.G. Novy, D. Stewart, H.V. Davies, and W.R. Belknap. 2007. Potato glycosterol rhamnosyltransferase, the terminal step in triose side-chain biosynthesis. Phytochemistry 68(3): 327–334.PubMedCrossRefGoogle Scholar
  13. Olsson, K. 1986. The influence of genotype on the effects of impact damage on the accumulation of glycoalkaloids in potato tubers. Potato Research 29(1): 1–12.CrossRefGoogle Scholar
  14. Oosumi, T., and W.R. Belknap. 1997. Characterization of the Sol3 family of nonautonomous transposable elements in tomato and potato. Journal of Molecular Evolution 45(2): 137–144.PubMedCrossRefGoogle Scholar
  15. Oosumi, T., B. Garlick, and W.R. Belknap. 1995. Identification and characterization of putative transposable DNA elements in solanaceous plants and Caenorhabditis elegans. Proceedings of the National Academy of Sciences U S A 92(19): 8886–8890.CrossRefGoogle Scholar
  16. Pustell, J., and F.C. Kafatos. 1982. A high speed, high capacity homology matrix: Zooming through SV40 and polyoma. Nucleic Acids Research 10(15): 4765–4782.PubMedCrossRefGoogle Scholar
  17. Rockhold, D.R., S.S. Chang, N.T. Taylor, P.V. Allen, K.F. McCue, and W.R. Belknap. 2008. Structure of two Solanum bulbocastanum polyubiquitin genes and expression of their promoters in transgenic potatoes. American Journal of Potato Research 85(3): 219–226.CrossRefGoogle Scholar
  18. Sinden, S.L., L.L. Sanford, and R.E. Webb. 1984. Genetic and environmental control of potato glycoalkaloids. American Potato Journal 61(3): 141–155.CrossRefGoogle Scholar
  19. Snyder, G.W., and W.R. Belknap. 1993. A modified method for routine Agrobacterium-mediated transformation of in vitro grown potato microtubers. Plant Cell Reports 12: 324–327.CrossRefGoogle Scholar
  20. Valkonen, J.T.P., M. Keskitalo, T. Vasara, and L. Pietila. 1996. Potato glycoalkaloids: A burden or a blessing? Critical Reviews in Plant Sciences 15: 1–20.Google Scholar
  21. Verwoerd, T.C., B.M.M. Dekker, and A. Hoekema. 1989. A small-scale procedure for the rapid isolation of plant RNAs. Nucleic Acids Research 17(6): 2362.PubMedCrossRefGoogle Scholar
  22. Wessler, S., T. Bureau, and S. White. 1995. LTR-retrotransposons and MITEs: Important players in the evolution of plant genomes. Current Opinions in Genetic Development 5: 8.Google Scholar
  23. Xin, Z., J.P. Velten, M.J. Oliver, and J.J. Burke. 2003. High-throughput DNA extraction method suitable for PCR. Biotechniques 34(820–824): 826.Google Scholar

Copyright information

© Potato Association of America 2011

Authors and Affiliations

  • Kent F. McCue
    • 1
  • David R. Rockhold
    • 1
  • Alyssa Chhan
    • 1
  • William R. Belknap
    • 1
  1. 1.USDA, Agricultural Research Service, Western Regional Research Center, Crop Improvement and Utilization Research UnitAlbanyUSA

Personalised recommendations