Figure 1.

Identification of the ALT1-Induced Transcript, MdhpRNA277, Which Produces Two Small RNAs, mdm-siR277-1 and mdm-siR277-2, Which Target Five R Genes in GD Apple Leaves.

(A) Identification of the ALT1-induced long hairpin transcript, MdhpRNA277, and accumulation of mdm-siR277-1 and mdm-siR277-2 after ALT1 inoculation, as determined by small RNA sequencing. The numbers on the right refer to the number of reads, and the red areas refer to the read abundance.

(B) RT-qPCR to detect mRNA levels showing that MdhpRNA277 is induced, but MdhpRNA271 is not, in ALT1-inoculated GD seedlings. The numbers on the x axis indicate HPI. Spore inoculum concentration: 2 × 10⁵ cfu/mL. Spore growth was measured at 6 d postinoculation (DPI). Error bars represent standard deviations calculated from three biological replicates (separate biological material) that were performed for each treatment.

(C) Chromosomal locations of the ALT1-induced MdhpRNA277 gene and the five target genes of mdm-siR277-1/2.

(D) mdm-siR277-1 and mdm-siR277-2 cleavage sites in the RPW8 domains of five target genes identified by 5′ RACE. The arrows indicate the positions of inferred cleavage sites, and the numbers above the sequences indicate the detected cleavage site of independent clones. MdRNL1, MdRNL2, MdRNL3, MdRNL4, and MdRNL5 contain an N-terminal RPW8 domain and a C-terminal NB-LRR domain.