Figure 4

cycam1-1 and cycam1-2 are highly susceptible to A. brassicae and its Tox. (A) The roots of 14-day old cycam1 and WT seedlings grown under LD conditions were exposed to a fungal plug for 7 d. (B) The leaves of 14-day old cycam1 and WT seedlings were inoculated with 5 μl spore suspension containing 10⁴-10⁵ cfu ml⁻¹ and incubated for 7 d. Detached leaf assays with mature leaves were performed with fungal spores and Tox (C). Mature leaves from 4 week-old cycam1 and WT plants were dissected, inoculated with 10 μl spore suspension containing 10⁴-10⁵ cfu ml⁻¹ or 10 μl Tox preparations and incubated for 5 d. (D) The Percentage Disease Index (PDI) was determined 3, 5, 7 and 10 days after infection (dai) of leaves as shown in panel C, left. The mock treatment was performed with sterile water. Bars represent means ± SEs, based on 4 x 24 leaves. Asterisks indicate significant differences as determined by the Student’s t-test (** P < 0.01). (E) A. brassicae AbreATR1 transcript levels are higher in cycam1-1 and cycam1-2 than in WT leaves 5 dai. –Ab, unifected control, +Ab, A. brassicae-infected leaves. The plant GAPDHC gene served as control. The gel pictures are representative of 4 independent experiments with 3 replications each. (F) 14-day old WT, cycam1-1 and cam1-2 seedlings, which were either grown on MS medium (left) or MS medium supplemented with A. brassicae Tox preparation (Tox, right). The bottom pictures show Chl fluorescence images of the seedlings shown on the top. (G) Fresh weight of seedlings which were grown as demonstrated in panel (F). In addition to the Tox, also the CWE, EPM or EPS preparations were tested. Data are means ± SEs from 5 independent experiments with >40 seedlings per treatment in each experiment (** P < 0.01).