Figure 4.

Quantification of SAR against Pp Noco2 in the different plant lines and immunolocalization of GSNOR in the phloem. SAR establishment was measured using the combination of avirulent bacteria (Psm avrRpm1) and virulent oomycete (Pp Noco2). Two rosette leaves of the different lines were infiltrated either with the avirulent bacteria (10⁶ cfu mL⁻¹) or mock inoculated with 10 mm MgCl₂, and 48 h later were sprayed with a suspension of the virulent oomycete (4 × 10⁴ spores mL⁻¹). Number of conidia was counted 6 d after Pp inoculation. The average of five independent measurements ± sd is represented in A for a typical experiment. The experiment was performed twice and the mean value ± sd is represented in B as the ratio of number of spores in plants previously infiltrated with Psm avrRpm1 or with MgCl₂ (bar height ratio). C, Total SNO levels in leaf extracts from the different Arabidopsis lines, either challenged or unchallenged with Psm avrRpm1 (10⁶ cfu mL⁻¹). Systemic and challenged leaves were collected at days 1, 2, and 3 after treatment. Values were normalized per milligram of protein. D, Immunodetection of GSNOR in the phloem. Immunolocalization was performed using specific antibodies against Arabidopsis GSNOR as described in Espunya et al. (2006). In the control panel, the antibody was preincubated with purified FALDH protein prior to the immunolocalization experiments. Bars: 25 μm. End, Endodermis; Cc, phloem companion cells; Vs, vascular system; Ep, epidermis.