The tomato gene Pti1 encodes a serine/threonine kinase that is phosphorylated by Pto and is involved in the hypersensitive response

Cell. 1995 Dec 15;83(6):925-35. doi: 10.1016/0092-8674(95)90208-2.


The Pto gene encodes a serine/threonine kinase that confers resistance to bacterial speck disease in tomato. Using the yeast two-hybrid system, we identified a second serine/threonine kinase, Pto-interacting 1 (Pti1), that physically interacts with Pto. Cross-phosphorylation assays revealed that Pto specifically phosphorylates Pti1 and that Pti1 does not phosphorylate Pto. Fen, another serine/threonine kinase from tomato that is closely related to Pto, was unable to phosphorylate Pti1 and was not phosphorylated by Pti1. Expression of a Pti1 transgene in tobacco plants enhanced the hypersensitive response to a P. syringae pv. tabaci strain carrying the avirulence gene avrPto. These findings indicate that Pti1 is involved in a Pto-mediated signaling pathway, probably by acting as a component downstream of Pto in a phosphorylation cascade.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • Genes, Plant / genetics*
  • Lycopersicon esculentum / embryology
  • Lycopersicon esculentum / genetics*
  • Molecular Sequence Data
  • Mutation
  • Phosphorylation
  • Plant Diseases / microbiology
  • Plant Proteins*
  • Plants, Toxic
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Pseudomonas / pathogenicity
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Signal Transduction / physiology*
  • Substrate Specificity
  • Tobacco / genetics
  • Transgenes


  • DNA, Complementary
  • Plant Proteins
  • Fen protein, Lycopersicon esculentum
  • Pto protein, Lycopersicon
  • Protein-Serine-Threonine Kinases

Associated data

  • GENBANK/U28007