Deletion of the mimp in the shared promoter region of SIX3 and SIX5 does not affect expression of the two genes. (A) Schematic representation of the SIX3/SIX5 locus. Black lines: deleted promoter fragments (length of the deletion in bp; pink box: mimp; yellow arrow: SIX gene; orange circles: sequence matching AAGTCGGCAGTT[AG] motif, which is enriched in SIX1-7 promoters. (B) In vitro expression of SIX3 and SIX5 in the promoter deletion strains. Mycelium of the indicated Fol strains was collected after growth in minimal medium, RNA was extracted and RT-PCR was performed. (C) In planta expression of SIX3 and SIX5 in the promoter deletion strains. Roots of ten days old susceptible (without resistance genes) or resistant (encoding the I-2 resistance protein that recognizes Six3) tomato seedlings were inoculated with the indicated Fol strains or with water (mock). Roots were harvested 9 dpi (days post inoculation), RNA was extracted and RT-PCR was performed as described above. Expression of SIX1 was used as a control. (D) Disease assay of tomato plants. Performed as above. Error bars indicate the 95% confidence interval of the mean. Numbers indicate the strains with which the tomato plants were inoculated: (1) mock, (2) Fol007 (WT), (3) SIX3p539#2, (4) SIX3p807#1, (5) SIX3p807#2, (6) SIX3p859#1, (7) SIX3p859#2. A black box marks interactions where recognition of Six3 by I-2 is broken or where no disease is caused.
Schmidt et al. BMC Genomics 2013 14:119 doi:10.1186/1471-2164-14-119