EDS1 in tomato is required for resistance mediated by TIR-class R genes and the receptor-like R gene Ve

Plant J. 2005 May;42(3):376-91. doi: 10.1111/j.1365-313X.2005.02380.x.

Abstract

In tobacco and other Solanaceae species, the tobacco N gene confers resistance to tobacco mosaic virus (TMV), and leads to induction of standard defense and resistance responses. Here, we report the use of N-transgenic tomato to identify a fast-neutron mutant, sun1-1 (suppressor of N), that is defective in N-mediated resistance. Induction of salicylic acid (SA) and expression of pathogenesis-related (PR) genes, each signatures of systemic acquired resistance, are both dramatically suppressed in sun1-1 plants after TMV treatment compared to wild-type plants. Application of exogenous SA restores PR gene expression, indicating that SUN1 acts upstream of SA. Upon challenge with additional pathogens, we found that the sun1-1 mutation impairs resistance mediated by certain resistance (R) genes, (Bs4, I, and Ve), but not others (Mi-1). In addition, sun1-1 plants exhibit enhanced susceptibility to TMV, as well as to virulent pathogens. sun1-1 has been identified as an EDS1 homolog present on chromosome 6 of tomato. The discovery of enhanced susceptibility in the sun1-1 (Le_eds1-1) mutant plant, which contrasts to reports in Nicotiana benthamiana using virus-induced gene silencing, provides evidence that the intersection of R gene-mediated pathways with general resistance pathways is conserved in a Solanaceous species. In tomato, EDS1 is important for mediating resistance to a broad range of pathogens (viral, bacterial, and fungal pathogens), yet shows specificity in the class of R genes that it affects (TIR-NBS-LRR as opposed to CC-NBS-LRR). In addition, a requirement for EDS1 for Ve-mediated resistance in tomato exposes that the receptor-like R gene class may also require EDS1.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Chromosome Mapping
  • Chromosomes, Plant
  • Genes, Plant / physiology*
  • Immunity, Innate / genetics
  • Molecular Sequence Data
  • Mutation
  • Plant Diseases / microbiology
  • Plant Diseases / virology
  • Plant Leaves / microbiology
  • Plant Proteins / genetics*
  • Plant Proteins / physiology*
  • Plant Viruses
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • Solanum lycopersicum / genetics*
  • Solanum lycopersicum / physiology*
  • Time Factors

Substances

  • Plant Proteins

Associated data

  • GENBANK/AY796114