Ks. Century et al., NDR1, A LOCUS OF ARABIDOPSIS-THALIANA THAT IS REQUIRED FOR DISEASE RESISTANCE TO BOTH A BACTERIAL AND A FUNGAL PATHOGEN, Proceedings of the National Academy of Sciences of the United Statesof America, 92(14), 1995, pp. 6597-6601
We have employed Arabidopsis thaliana as a model host plant to genetic
ally dissect the molecular pathways leading to disease resistance, A.
thaliana accession Col-O is susceptible to the bacterial pathogen Pseu
domonas syringae pv, tomato strain DC3000 but resistant in a race-spec
ific manner to DC3000 carrying any one of the cloned avirulence genes
avrB, avrRpm1, avrRpt2, and avrPph3. Fast-neutron-mutagenized Col-O M(
2) seed was screened to identify mutants susceptible to DC3000(avrB).
Disease assays and analysis of in planta bacterial growth identified o
ne mutant, ndr1-1 (non-race-specific disease resistance), that was sus
ceptible to DC3000 expressing any one of the four avirulence genes tes
ted. Interestingly, a hypersensitive-like response was still induced b
y several of the strains. The ndr1-1 mutation also rendered the plant
susceptible to several avirulent isolates of the fungal pathogen Peron
ospora parasitica. Genetic analysis of ndr1-1 demonstrated that the mu
tation segregated as a single recessive locus, located on chromosome I
II. Characterization of the ndr1-1 mutation suggests that a common ste
p exists in pathways of resistance to two unrelated pathogens.