Abstract:By spraying β-aminobutyric acid （BABA） or/and leaf wounding treatments, the activities of defenserelated enzymes were determined to investigate the interaction effects of BABA and wounding on the resistance of tobacco （Nicotiana tabacum L. cv.Yunyan 85） to tobacco mosaic virus （TMV）. The results showed that wounding or BABA treatment caused a significant increase of phenylalanine ammonia-lyase （PAL） and polyphenol oxidases （PPO） activities, which were associated with BABA concentrations and timing of induction. However, leaf wounded by pruning in combination with addition of BABA decrease the activities of PAL and PPO, resulting in obviously more TMV symptoms than BABA treatment alone. The results suggest that BABA and wounding exhibit antagonistic effect. It is likely that BABA and other SA-dependent chemical inducers should not be applied to the wounded tobacco seedlings.