Planta

, Volume 235, Issue 6, pp 1341–1353

Induction of potato steroidal glycoalkaloid biosynthetic pathway by overexpression of cDNA encoding primary metabolism HMG-CoA reductase and squalene synthase

  • Idit Ginzberg
  • Muddarangappa Thippeswamy
  • Edna Fogelman
  • Ufuk Demirel
  • Alice M. Mweetwa
  • James Tokuhisa
  • Richard E. Veilleux
Original Article

DOI: 10.1007/s00425-011-1578-6

Cite this article as:
Ginzberg, I., Thippeswamy, M., Fogelman, E. et al. Planta (2012) 235: 1341. doi:10.1007/s00425-011-1578-6

Abstract

Potato steroidal glycoalkaloids (SGAs) are toxic secondary metabolites whose total content in tubers must be regulated. SGAs are biosynthesized by the sterol branch of the mevalonic acid/isoprenoid pathway. In a previous study, we showed a correlation between SGA levels and the abundance of transcript coding for HMG-CoA reductase 1 (HMG1) and squalene synthase 1 (SQS1) in potato tissues and potato genotypes varying in SGA content. Here, Solanum tuberosum cv. Desirée (low SGA producer) was transformed with a gene construct containing the coding region of either HMG1 or SQS1 of Solanum chacoense Bitt. clone 8380-1, a high SGA producer. SGA levels in transgenic HMG-plants were either greater than (in eight of 14 plants) or no different from untransformed controls, whereas only four of 12 SQS-transgenics had greater SGA levels than control, as determined by HPLC. Quantitative real-time PCR was used to estimate relative steady-state transcript levels of isoprenoid-, steroid-, and SGA-related genes in leaves of the transgenic plants compared to nontransgenic controls. HMG-transgenic plants exhibited increased transcript accumulation of SQS1, sterol C24-methyltransferase type1 (SMT1), and solanidine glycosyltransferase 2 (SGT2), whereas SQS-transgenic plants, had consistently lower transcript levels of HMG1 and variable SMT1 and SGT2 transcript abundance among different transgenics. HMG-transgenic plants exhibited changes in transcript accumulation for some sterol biosynthetic genes as well. Taken together, the data suggest coordinated regulation of isoprenoid metabolism and SGA secondary metabolism.

Keywords

HMGR1 Isoprenoid pathway Potato steroidal glycoalkaloids Secondary metabolism Squalene synthase Transgenic Solanum 

Abbreviations

HMGR

3-Hydroxy-3-methylglutaryl coenzyme A reductase

CAS

Cycloartenol synthase

Chc80-1

S. chacoense clone 8380-1

CYP51G

Obtusifoliol 14-α-demethylase

DWF

DWARF

FK

Fackel

HYD1

C-8 sterol isomerase

LAS

Lanosterol synthase

SGA

Steroidal glycoalkaloids

SGT1

Solanidine galactosyltransferase

SGT2

Solanidine glucosyltransferase

SGT3

Steroidal glycoalkaloid rhamnosyltransferase

SMO

4- α methyl oxidase

SMT

Sterol C24-methyltransferase

SQS

Squalene synthase

Supplementary material

425_2011_1578_MOESM1_ESM.pdf (103 kb)
Supplementary material 1 (PDF 103 kb)
425_2011_1578_MOESM2_ESM.pdf (148 kb)
Supplementary material 2 (PDF 148 kb)
425_2011_1578_MOESM3_ESM.pdf (213 kb)
Supplementary material 3 (PDF 212 kb)
425_2011_1578_MOESM4_ESM.pdf (99 kb)
Supplementary material 4 (PDF 98 kb)

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Idit Ginzberg
    • 1
  • Muddarangappa Thippeswamy
    • 1
    • 5
  • Edna Fogelman
    • 1
  • Ufuk Demirel
    • 1
    • 3
  • Alice M. Mweetwa
    • 2
    • 4
  • James Tokuhisa
    • 2
  • Richard E. Veilleux
    • 2
  1. 1.Institute of Plant SciencesARO, the Volcani CenterBet DaganIsrael
  2. 2.Department of HorticultureVirginia Tech BlacksburgVirginiaUSA
  3. 3.Department of Field CropsHarran UniversitySanliurfaTurkey
  4. 4.University of ZambiaLusakaZambia
  5. 5.Department of BiochemistryIndian Institute of ScienceBangaloreIndia

Personalised recommendations