Fc 43

P. triticina isolates B9414, 93012, 94015, 95012, 96007 and 96237 are avirulent on Lr9 (refs. ^{52 ,53 (link)}). Isolate MNPSD is virulent on Lr9 (ref. ^{54 (link)}). Isolates were propagated on seedlings of the susceptible wheat cultivar Thatcher. Freshly collected urediniospores were used for inoculation experiments. Inoculations were performed using a high-pressure air sprayer or a settling tower. For the spray inoculation, urediniospores were suspended in FC-43 oil (3M Fluorinert FC-43) and sprayed onto plants using a glass sprayer connected to a high-pressure air pipe. For the settling tower inoculation, plants were grown for 12 d. Then, the second leaf was removed and the first leaf was pinned to the soil with the adaxial side facing upward. A mixture of 10 mg urediniospores and 300 mg lycopodium powder (Sigma-Aldrich, 19108) was blown over the plants in a settling tower^{55 (link)}. Inoculated plants were placed in an inoculation box equipped with a humidifier overnight and transferred to a walk-in Conviron growth room (16 h day/8 h night, 18 °C/16 °C). Symptoms were evaluated 12 d after inoculation. Infected leaves were scanned using an Epson Perfection V600 Photo scanner.

125-µm-thick polyethylene naphthalate (PEN) films (Teijin, Teonex) were used as substrates without cleaning process. A 100-nm-thick Ag electrode was formed by inkjet-printing a silver nanoparticle ink (Harima Chemicals, NPS-JL) on the PEN substrates, followed by an annealing process of 120 °C for 30 minutes in the air. Then, a carbon graphite ink including prussian blue (Gwent Group) was coated on the printed Ag electrode, followed by an annealing process of 60 °C for 30 minutes in the air. In order to define the sensing area, a fluoropolymer solution (5 wt%, DuPont, Teflon AF1600) in Fluorinert (3M, FC-43) was printed as a bank onto the substrate except the sensing area by a dispenser, followed by an annealing process of 60 °C for 30 minutes in the air. 10 µl of the chitosan solution and 1.4 µl of the lactate solution was mixed. Then, 10 µl of the mixed solution was drop-casted onto the area defined by the fluoropolymer bank, followed by a drying process of 30 °C for 3 h in the air. The sensor electrodes were dipped in phosphate-buffered saline (PBS) and stored at 4 °C.