EDS1 in tomato is required for resistance mediated by TIR-class R genes and the receptor-like R gene Ve.
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.
Hu
Gongshe
G
USDA, Plant Gene Expression Center, 800 Buchanan St, Albany, CA 94710, USA.
deHart
Amy K A
AK
Li
Yansu
Y
Ustach
Carolyn
C
Handley
Vanessa
V
Navarre
Roy
R
Hwang
Chin-Feng
CF
Aegerter
Brenna J
BJ
Williamson
Valerie M
VM
Baker
Barbara
B
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
D010940:Plant Proteins