Planta

, Volume 208, Issue 3, pp 310–318

Regulation of tomato HMG1 during cell proliferation and growth

  • John G. Jelesko
  • Susan M. Jenkins
  • Manuel Rodríguez-Concepción
  • Wilhelm Gruissem
Article

Abstract.

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC 1.1.1.34) is encoded by a small multigene family in tomato (Lycopersiconesculentum Mill.) and catalyzes the synthesis of mevalonic acid (MVA), a committed step in the biosynthesis of sterols and isoprenoids. A chimeric HMG1::GUS reporter gene fusion was used to analyze the regulation of HMG1 gene expression in detail. HMG1 promoter 5′ deletion mutants established the boundary of a fully inducible promoter. In HMG1::GUS transgenic tomato plants, histochemical staining with 5-bromo-3-indolyl-glucuronide demonstrated that HMG1 was primarily expressed in shoot and root meristems, and in young tomato fruit. This result was confirmed by both HMG1 in-situ hybridization and RNA gel blot analysis. Tomato suspension cell experiments showed that steady-state HMG1 mRNA accumulated during lag and exponential growth phases, but not during the stationary phase. Transient expression of the HMG1::GUS in tissue culture cells treated with mevinolin indicated that HMG1 expression was subject to feedback regulation by a biosynthetic product derived from MVA. These results suggest that a primary, although not exclusive, role of HMG1 is to supply the MVA demand associated with cell division and growth.

Keywords:β-Glucuronidase 3-Hydroxy-3-methylglu- taryl coenzyme A reductase Lycopersicon (HMG1 regulation) Mevalonic acid Transgenic tomato Transient gene expression (HMG1) 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • John G. Jelesko
    • 1
  • Susan M. Jenkins
    • 1
  • Manuel Rodríguez-Concepción
    • 1
  • Wilhelm Gruissem
    • 1
  1. 1.Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102, USAUS

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