Early Detection of Asian Soybean Rust Using PCR

Fig. 4. Real-time PCR of soybean leaves infected with Phakopsora pachyrhizi performed using the Cepheid Smart Cycler. The vertical axis shows the cycle threshold (Ct) value (the PCR cycle when fluorescence exceeds background) that indicates a positive identification. The horizontal axis indicates the number of days after inoculation at which each sample was collected. DNA was extracted from inoculated leaves using the DNeasy Plant Mini kit (QIAGEN) and tested at two dilutions at the inoculum concentration as follows: (A) 1:2 DNA dilution, inoculum at 12,500 spores/ml; (B) 1:20 DNA dilution, inoculum at 12,500 spores/ml; (C) 1:2 DNA dilution, inoculum at 25,000 spores/ml; (D) 1:20 DNA dilution, inoculum at 25,000 spores/ml; (E) 1:2 DNA dilution, inoculum at 100,000 spores/ml; and (F) 1:20 DNA dilution, inoculum at 100,000 spores/ml.



Image from Plant Health Progress article:
Early Detection of Asian Soybean Rust Using PCR