FIGURE 2.

Characterization of P. indica Knockout Strains Pi_Δ08944 (PiT1-PiT5). (A) Roots of 7-day-old Arabidopsis seedlings were inoculated with chlamydospores of Pi_Δ08944 strains PiT1 or PiT2, respectively. The roots were harvested at 3, 7, 14, and 21 dpi and PIIN_08944 transcript levels were determined from extracted RNA by RT-PCR using PIIN_08944 specific primer. PIIN_08944 transcripts from Pi_Δ08944 strains were not detected in planta. The P. indica ubiquitin UBQ gene served as reference. (B) Deletion of PIIN_08944 delays colonization of Arabidopsis roots. Roots of 7-day-old Arabidopsis seedlings were inoculated with Pi_Δ08944 (PiT1) and wt, respectively. (C) Colonization of PIIN_08944-expressing Arabidopsis with Pi_Δ08944 (PiT1) mutant. Roots of 7-day-old AtPIIN_08944OE seedlings or wt were inoculated with Pi_Δ08944. Fungal biomass was determined at 3, 7, 14, and 21 dpi as relative amount of fungal DNA by qPCR using fungal (ITS) and plant (AtUBQ4) specific primers. Data displays the Ct thresholds of ITS relative to the Ct thresholds of AtUBQ- 4 (±SE obtain from three technical replicates of one biological experiment). Experiments were repeated twice with similar results. Asterisks indicate significance at ^∗P < 0.05, ^∗∗P < 0.01 analyzed by Student’s t-test.