Tóm tắt
Begomoviruses are among the most devastating plant viruses. They have compact genomes that encode six to eight proteins important for viral replication and spread. Among these proteins, AC4 (C4 in monopartite begomoviruses) is a multifunctional protein with roles in host immunity suppression and disease symptom expression. Here, we investigated the role of AC4 in the infectivity of pepper yellow leaf curl Thailand virus, a begomovirus recently reported in central Vietnam. First, three AC4-null mutants were created from the infectious clones of DNA-A of PepYLCThV using QuikChange site-directed mutagenesis. The mutants were confirmed with PCR and DNA sequencing. The wild-type and mutants infectious clones were used to infect Nicotiana benthamiana via agroinoculation. Symptom expression was monitored for up to 28 days post inoculation. Disease onset started at five to six days post inoculation. Inoculation with AC4-null mutant infectious clones, similar to wild-type AC4 infectious clones, resulted in severe leaf distortion, mosaic, white patches on leaves and stunted growth in 100% of inoculated plants. Furthermore, the presence of DNA-A and DNA-B were confirmed in infected plants by PCR. These results suggested AC4 plays an insignificant role in the infectivity of PepYLCThV in the model plant N. benthamiana.