SA accumulation and HR development in leaves of Col-0, Col-3, cry1cry2, phot1phot2, and phyAphyB plants treated with Psm avrRpm1 (OD = 0.005). Inoculations were performed at 10 am within the light/dark regime depicted in . A, Total SA levels in leaves 10 h after Psm avrRpm1 or MgCl2 treatment. Bars represent mean values (± sd) of three independent samples, each sample consisting of six leaves from two different plants. Asterisk denotes value with statistically significant difference to the values of the respective wild type (*, P < 0.05; Student's t test). Light bars, MgCl2-treatment; dark bars, Psm avrRpm1 inoculation. B, Microscopic HR lesions of representative leaf samples at 24 hpi with Psm avrRpm1, as assessed by trypan-blue staining. For all lines under investigation, inoculated leaf areas harbor patches of blue-stained, dead cells clearly delimited from surrounding healthy (unstained) tissue (magnification 100-fold). For comparison, the staining outcome of an MgCl2-treated Col-0 leaf is depicted (bottom right). Similar staining results were obtained for MgCl2-treated leaves of the remainder lines (not shown).