Control efficacy of daphnetin against tobacco bacterial wilt and its action mechanism
To investigate the control efficacy of daphnetin on tobacco bacterial wilt and explore the in-duced systemic resistance of daphnetin on tobacco plants,the pot and field experiments were per-formed,respectively. Then,plant enzymes,lignin content and plant resistance genes under daphnetin treatment were evaluated by high performance liquid chromatography (HPLC) and real-time quantita-tive PCR. The results showed that spray application of 2.85 mg/L daphnetin had the optimal control effi-cacy on tobacco bacterial wilt,with control efficacy of 66.93％ at 14 days after inoculation with Ralsto-nia solanacearum,which was more efficient than 5.70 mg/L and 11.40 mg/L daphnetin treatment,with control efficacy as 42.52％ and 48.03％,respectively. Furthermore,daphnetin could significantly induce the activity of plant enzymes,including peroxidase (POD),phenylalanin ammonialyase (PAL) and poly-phenol oxidase (PPO),which were improved 3.56-,1.68-,and 1.82-times compared with control treat-ment at 12 h after application. Lignin content of tobacco roots was significantly induced 1.33-fold and 1.54-fold at 4 d and 7 d after daphnetin application. Compared with the control at 6 h after daphnetin ap-plication,jasmonic acid and abscisic acid contents in tobacco were significantly increased by 35.98％ and 34.55％,while salicylic acid content significantly decreased by 25.56％ . Meanwhile,daphnetin could significantly down-regulate expression level of jasomonate ZIM-domain 3 (JAZ3) with 9.19-fold,and induce expression level of pathogenesis-related protein gene 1 (PR1). Control efficacy of 2.85 mg/L daphnetin treatment was 52.22％-75.54％ in field conditions,significantly higher than benzothiadiazole treatment with 33.50％-53.00％ . Therefore,application of daphnetin improved plant enzyme activity and root lignin content,inducing expression levels of plant resistance genes,and displayed stable filed control efficacy on tobacco bacterial wilt. Thus daphnetin could be used as an alternative plant elicitor for controlling tobacco bacterial wilt.
万方数据
维普
