Fig. 4.

HCPro interacted with CAT1 and CAT3 and inhibited their activities. (A) Gene expression of CAT1 and CAT3, and (B) their protein accumulations in the HCPro-OX lines and WT plants (using 8-week-old seedlings). (C) CAT1, (D) CAT2, and (E) CAT3 enzyme activity assays in reactions containing varying molar ratios of MBP–CAT to deletion mutants of HCPro. CAT (500 pM) was incubated with or without HCPro deletion mutants at 37 °C for the indicated times. MBP was used as negative control. The full length of HCPro is marked as HCPro. HC-N, amino acids 1–100; HC-C, amino acids 301–457. (F) Catalase activity and (G) H₂O₂ content in the HCPro-OX lines and WT plants (using 8-week-old seedlings). (H) Necrosis symptoms, (I) coat protein (CP) accumulation, and (J) virus replication of EV, CAT1, and CAT3 introduced into cat1cat3-KO plants under ChiVMV infection. The circles indicate the area of necrosis. Scale bars=2.5 cm. (K) Catalase activity and (L) H₂O₂ content in EV, CAT1, and CAT3 introduced into cat1cat3-KO plants. Fw, fresh weight; EV, empty vector. Values are means and SDs from three biological replicates per genotype and time point. Lower case letters indicate statistically significant differences (P<0.05).