Rapid DNA Extraction from Plant and Insect Samples

For all plants used, total DNA extraction was performed as previously described (4 (link), 25 (link)). Briefly, three different leaves located immediately below the apex of infected plants were squashed onto a Whatman paper disk of 0.6 cm diameter. Each disk was individually deposited onto the filter of a 200 µL micropipette tip. Then, 100 µL of modified Edwards buffer [200 mM Tris-HCl pH 7.5, 25 mM EDTA, 250 mM NaCl, 0.5% SDS, 1% polyvinylpyrrolidone 40 (PVP40), and 0.2% ascorbic acid] was added and centrifugation at 5,000 g for 15 s was performed directly into a PCR plate placed underneath. Finally, DNA was precipitated with 50% isopropanol (final concentration), rinsed with 70% EtOH, and resuspended in 30 µL nuclease-free H₂O. Pestle-crushed whole aphids and dissected heads or guts, hemolymph, AP3 medium, and purified virus samples were extracted using the Purelink Plant Total DNA Purification Kit (Invitrogen) according to the manufacturer’s instructions. DNA was resuspended in 70 µL nuclease-free H₂O.