title: EDS1 in tomato is required for resistance mediated by TIR-class R genes and the receptor-like R gene Ve.
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.
authors.affiliation: USDA, Plant Gene Expression Center, 800 Buchanan St, Albany, CA 94710, USA.
authors.forename: Gongshe
authors.initials: G
authors.lastname: Hu
authors.forename: Amy K A
authors.initials: AK
authors.lastname: deHart
authors.forename: Yansu
authors.initials: Y
authors.lastname: Li
authors.forename: Carolyn
authors.initials: C
authors.lastname: Ustach
authors.forename: Vanessa
authors.initials: V
authors.lastname: Handley
authors.forename: Roy
authors.initials: R
authors.lastname: Navarre
authors.forename: Chin-Feng
authors.initials: CF
authors.lastname: Hwang
authors.forename: Brenna J
authors.initials: BJ
authors.lastname: Aegerter
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Williamson
authors.forename: Barbara
authors.initials: B
authors.lastname: Baker
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D017343:Genes, Plant / Q000502:physiology*; D007113:Immunity, Innate / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics* / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology / Q000821:virology; D018515:Plant Leaves / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology*; D010942:Plant Viruses; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D010940:Plant Proteins