Abstract：Protein elicitor from Verticillium dahliae(PevD1, UniProtKB accession No. P86840) was isolated from V. dahliae culture filtrate. To functionally investigate the mechanisms of disease resistance induced by the elicitor, we have expressed and purified the recombinant protein, 6His-PevD1 in Escherichia coli, The recombinant protein could cause cell death in tobacco (Nicotiana tabacum cv. Samsun-NN) cell suspension and enhanced the systemic resistance of tobacco to Tobacco mosaic virus (TMV). The rate of necrosis reduction by the elicitor treatment could be up to 46.64%. The activities of phenylalanine ammonia lyase(PAL), polyphenol oxidase(PPO) and peroxidase(POD) were increased significantly upon PevD1 treatment in tobacco leaves. The maximal activity of PAL appeared at 144 h post the treatment, which was 3.3 times as high as that of the untreated control. And the activities of PPO and POD increased by 236.8% and 204.6% after 120 h post the treatment, respectively. Transcription of acid pathogenesis-related gene 1(PR1-a), basic pathogenesis-related gene 1(PR1-b), non-expresser of pathogenesis-related gene 1(NPR1) and phenylalanine ammonia lyase gene (PAL) was upregulated after PevD1 treatment as well. Taken together, these results demonstrate that the activity enhancement of defense-related enzymes and the induction of resistance-related genes' expression are the key mechanisms underlying the systemic acquired resistance (SAR) induced by PevD1 in tobacco.
