Fig. 4

Bidirectional transcription of P. sojae Avr1b locus. a The model and method for detection of the bidirectional transcription of the Avr1b locus. Avr1b(+) and Avr1b(−) are organized in a tail-to-tail manner with more than 200 bp overlapping sequence. Oligo dT with an adaptor sequence (in red) was used for the first strand cDNA synthesis, and PCR was performed by using the combinations of Avr1b-asRNA sense (small blue arrow) primer, Avr1b-asRNA antisense (small black arrow) and the adaptor (small red arrow) primers. P, the promoter. b RT-PCR validation of the bidirectional transcription. G. max cultivar Williams (rps1b) infected with different strains of P. sojae were sampled at 0, 1, 2, and 3 dpi, respectively. Equal amount of total RNAs were used for each RT-PCR assays. RT(+) indicates the amplicon of RT-PCR, and RT(−) indicates the control reactions without cDNA synthesis (no reverse transcriptase applied). PsActA was amplified for 30 cycles and was used as a reference gene, while Avr1b(+) and Avr1b(−) were amplified for 35 cycles