Genetic and physiological characterization of tomato cv. Micro-Tom

J Exp Bot. 2006;57(9):2037-47. doi: 10.1093/jxb/erj154. Epub 2006 May 10.

Abstract

Based on its compact habit, Micro-Tom, a dwarf cultivar of tomato (Solanum lycopersicum L.), has been proposed as a preferred variety to carry out molecular research in tomato. This cultivar, however, is poorly characterized. It is shown here that Micro-Tom has mutations in the SELF-PRUNING (SP) and DWARF (D) genes. In addition to this, it is also shown that Micro-Tom harbours at least two independently segregating resistance loci to the plant pathogen Cladosporium fulvum. The presence of the self-pruning mutation in Micro-Tom, that generates a determinate phenotype, was confirmed by crossing and sequence analysis. It was also found that Micro-Tom has a mutation in the DWARF gene (d) that leads to mis-splicing and production of at least two shorter mRNAs. The d mutation is predicted to generate truncated DWARF protein. The d sequence defect co-segregates with dark-green and rugose leaves, characteristics of brassinosteroid biosynthesis mutants. Micro-Tom also carries at least another mutation producing internode length reduction that affects plant height but not active gibberellin (GA) levels, which were similar in dwarf and tall Micro-TomxSeverianin segregants. GAs and brassinosteroids act synergistically in Micro-Tom, and the response to GA depends on brassinosteroids because the elongation of internodes was at least six times higher when GA(3) was applied simultaneously with brassinolide. A novel variety, Micro-0 that is fully susceptible to C. fulvum and almost as dwarf as Micro-Tom, has been generated from the cross of Cf0xMicro-Tom. This line represents a valuable resource for future analysis of Cf resistance genes through breeding or transformation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cladosporium / physiology*
  • Gibberellins / metabolism
  • Gibberellins / physiology*
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Plant Growth Regulators / metabolism
  • Plant Growth Regulators / physiology*
  • Plant Proteins / genetics*
  • Plant Proteins / physiology
  • RNA Splicing
  • Solanum lycopersicum / genetics*
  • Solanum lycopersicum / microbiology
  • Solanum lycopersicum / physiology
  • Steroids / metabolism
  • Steroids / physiology*

Substances

  • Gibberellins
  • Plant Growth Regulators
  • Plant Proteins
  • SP protein, Lycopersicon esculentum
  • Steroids