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Pokeweed antiviral protein(PAP)increases plant resistance to Tobacco mosaic virus infection in Nicotiana benthamiana

Feng Zhu;Yizhong Yang

  Ribosome-inactivating proteins(RIPs) are toxic N-glycosidases that depurinate the universally conserved orsarcin loop of large eukaryotic and prokaryotic rRNAs,thereby arresting protein synthesis at translation.RIPs are widely distributed in various plant species and within a variety of different tissues.As for plants,RIPs have been linked to defense by antibacterial,antiviral,antifungal,and insecticidal properties demonstrated in vitro and in transgenic plants.Pokeweed antiviral protein(PAP) is a 29 kDa type I RIP isolated from the leaves of the pokeweed plant(Phytolacca americana).Our recent study demonstrated that the PAP purified from the leaves of the pokeweed plant has distinct antiviral activity.Nicotiana benthamiana leaves pre-treated with 0.2 mg/mL PAP three days before inoculated with Tobacco mosaic virus(TMV) showed less-severe symptom and less reactive oxygen species(ROS) accumulation compared with that inoculated with TMV only but no PAP pre-treatment.Quantitative real-time PCR analysis revealed that the replication levels of TMV were lower in the PAP-treated leaves compared with the control plants at 7 days post inoculation.Out results indicated that PAP increases plant resistance to TMV infection.We think that PAP may act on ribosomes of infected plant cells,thereby inhibit the synthesis of viral protein.The results will be useful to design appropriate strategies for transgenic resistance in crop plants and PAP could possibly be exploited in crop protection.……