The purified, single, recombinant RNAs, total RNAs extracted from plants and total virion RNAs were also reverse transcribed using primers T3 0 and C3 0 , respectively. T3 0 is complementary to the 3 0 -terminal sequence of TAV, while C3 0 is complementary to the 3 0 -terminal sequence of Q-CMV (see Supplementary Table 1 for details). The synthesized first-strand cDNAs from the templates were amplified with different pairs of primers, C3 0 /T3-1187, C3 0 /C2-980, C3 0 /C1-2032, T3 0 /T3-1187, T3 0 /C2-980 and T3 0 /C1-2032 (see Supplementary Table 1 for details), using the thermocycler program: 1 min at 948C, 1 min at 528C and 2 min at 728C for 30 cycles.