Isolate B1 was used as a positive control for AVR-Pi9 primers and isolate ZN61 as a positive control for AVR-Pita1 primers [11]. Under a class II type A/B3 flow hood, a filter paper piece from the stored tube containing 5-month-old mycelia and spores was removed and dipped in

a 0.2 mL Eppendorf tube containing 100 μL 10 × (Tris and EDTA, pH 7.5) (Fig. 1). The tube was then heated at 95 °C for 10 min in a thermocycler (PTC-200, MJ Research, Waltham, MA, USA) and centrifuged at 3000 r min− 1 for 1 min. This DNA extracted for 11 min was stored at 4 °C in a refrigerator until use for PCR amplification. Two sets of primers were designed from the AVR-Pi9 gene (B. Zhou, unpublished data). One set was AVR9-BZ forward (5′-CTG CTC CAT CTT 5-Fluoracil mw GTT TGG CC-3′), and AVR9-BZ reverse (5′-CAC TAG TAC AAG CAC TAA CC-3′) amplifying a 1 kb genomic fragment. The other set was AVR9-YJ-forward (5′-ATC CCC ATC CAC AGG ATT Alectinib clinical trial CC-3′) and AVR9-YJ-reverse (5′-GTG CTT ACT ACT TAG TAT AA-3′) amplifying a 660 bp genomic fragment. The latter were designed using PRIMER 3 (http://biotools.umassmed.edu/bioapps/primer3_www.cgi) based on a genomic sequence encompassing the AVR-Pi9 locus ( [10]; Y. Jia and B. Zhou, unpublished data). These primers were known to amplify a fragment of about 660 bp of the AVR-Pi9 coding region. All PCR

reactions were performed using Taq PCR Master Mix (Qiagen Inc., Valencia, CA, USA). Each PCR consisted of the following components: 10 μL of Taq PCR Master Mix (contains 5 U of Taq DNA polymerase, 2 × Qiagen PCR buffer, 3 mmol L− 1 MgCl2, and 400 μmol L− 1 of each dNTP), 0.5 μL of each 100 μmol L− 1 primer, 1 μL fungal genomic DNA solution, and 9 μL distilled water (provided by the Qiagen Kit) in a final reaction volume of 20 μL. Reactions were performed in a thermocycler (PTC-200, MJ Research, Waltham, MA, USA) with the following PCR program: 1 cycle at 95 °C for 3 min for initial denaturation, 29 cycles at 94 °C for 30 s,

55 °C for 30 s, 72 °C for 60 s, and a final extension at 72 °C for 8 min. The PCR products Quinapyramine were separated by 1.0% (w/v) agarose gel electrophoresis in 1 × TAE, and stained with SYBR Green Safe (Invitrogen Inc., Grand Island, NY, USA). The gel was visualized and photographed using a Bio-Rad gel photographic system, Chemi Doc MP (Bio-Rad Laboratories, Inc., Hercules, CA, USA). The size of the amplified fragment was estimated with a Bioline hyperladder 1 kb plus (Bioline USA Inc., Taunton, MA, USA). To evaluate the stability of the DNA extracted directly from inoculated filter paper pieces, PCRs were repeated on days 4, 8, 10, and 18 of refrigerated storage. The tests were performed independently using the same sets of samples following a similar amplification protocol. The same DNA samples were used to amplify AVR-Pita1 using primers YL149/YL169 on day 18 of storage using the protocol described by Dai et al. [11] For a positive control, DNA from ZN61 extracted conventionally was used [12].