RESUMO
Geminiviruses are an important group of viruses that infect a variety of plants and result in heavy agricultural losses worldwide. The homologs of C4 (or L4) in monopartite geminiviruses and AC4 (or AL4) in bipartite geminiviruses are critical viral proteins. The C4 proteins from several geminiviruses are the substrates of S-acylation, a dynamic post-translational modification, for the maintenance of their membrane localization and function in virus infection. Here we initiated a screening and identified a plant protein ABAPT3 (Alpha/Beta Hydrolase Domain-containing Protein 17-like Acyl Protein Thioesterase 3) as the de-S-acylation enzyme of C4 encoded by BSCTV (Beet severe curly top virus). Overexpression of ABAPT3 reduced the S-acylation of BSCTV C4, disrupted its plasma membrane localization, inhibited its function in pathogenesis, and suppressed BSCTV infection. Because the S-acylation motifs are conserved among C4 from different geminiviruses, we tested the effect of ABAPT3 on the C4 protein of ToLCGdV (Tomato leaf curl Guangdong virus) from another geminivirus genus. Consistently, ABAPT3 overexpression also disrupted the S-acylation, subcellular localization, and function of ToLCGdV C4, and inhibited ToLCGdV infection. In summary, we provided a new approach to globally improve the resistance to different types of geminiviruses in plants via de-S-acylation of the viral C4 proteins and it can be extendedly used for suppression of geminivirus infection in crops.
RESUMO
Geminiviruses are a large group of plant viruses that have been a serious threat to worldwide agriculture. Transcription of the virus-encoded genes is necessary for geminiviruses to complete their life cycle, but the host proteins which directly target geminivirus promoters for suppression of viral gene transcription remain to be identified. Using Beet severe curly top virus (BSCTV) which causes severe plant symptoms as a system, we performed a yeast one-hybrid screening and identified ABA INSENSITIVE 5 (ABI5), a critical transcription factor in Abscisic acid (ABA) signaling transduction, as an interactor with the viral promoter. Further data showed that an ABA-responsive element in the viral promoter is necessary for its interaction with ABI5 and symptom development. Overexpression of ABI5 suppresses the transcription activity of the viral promoter and BSCTV infection in Nicotiana benthamiana and Arabidopsis; whilst depletion of ABI5 enhances the infection of BSCTV in Arabidopsis. Taken together, our study uncovered the function of ABI5 in the plant-virus interaction and will provide us with a new strategy to protect crops from geminivirus infection.
