Silencing of BiP4/5, HSP90 or SGT1 in Nicotiana benthamiana reduced HRT protein expression. (A) Verification of CaBLP5, SGT1 and HSP90 gene silencing in N. benthamiana plants. The expression of CaBLP5, SGT1 and HSP90 genes in the silenced plants at 21 days post‐infiltration (dpi) was analysed by quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) using the specific primers shown in Table S2, and the values were normalized to the level of NbActin. Error bars represent standard deviation (n = 3). Means with the same letter are not significantly different (t‐test, P < 0.05). Normal N. benthamiana leaves (non‐virus‐induced gene silenced) were also used as a control. (B) Levels of BiP, HRT‐HA, TCV CP and HSP90 in BiP4/5‐silenced N. benthamiana leaves. Total proteins were isolated from leaves of the indicated gene‐silenced N. benthamiana, co‐infiltrated with haemagglutinin (HA)‐tagged HRT and Turnip crinkle virus coat protein (TCV CP). The protein extracts were analysed by immunoblotting with anti‐BiP, anti‐cytosol‐resident HSP70, anti‐HSP90, anti‐HA or anti‐TCV CP antibodies to detect the protein levels.