Down-regulation of two ALS genes simultaneously via VIGS compromises Ol-1 -mediated resistance. (A), Effects of VIGS on growth and O. neolycopersici infection of NIL-Ol-1 plants infiltrated with empty vector as the control (TRV-EV) and TRV-U196237. (B), Quantification of fungal biomass of TRV-EV plants and TRV-U196237 plants. Values were normalized relative to elongation factor 1α (EF), and calibrated to levels in TRV-EV plants. Error bars represent standard deviation of five TRV-EV and ten TRV-U196237 plants. For each plant DNA was extracted from pooled 3rd and 4th leaves. (C), Transcript levels of ALS1, ALS2, and ALS3 in green and chlorotic areas of TRV-U196237 leaves. Values were normalized relative to EF, and calibrated to levels in green area. Error bars represent standard deviation of five biological replicates. Asterisks indicate significant difference from the control according to independent-samples t-test (P <0.05).