Effect and Mechanism of cis-Abienol to Induce Tobacco against

Bacterial Wilt

In order to explore the appropriate treatment conditions and the mechanism of cis-abienol to induce tobacco against bacterial wilt, the suitable root application concentration, time interval and frequency were investigated by pot inoculation, combined with determination of the changes of major defense enzyme activities, phytoalexin and phytohormone contents in tobacco roots after cis-abienol treatment. Additionally, the effect of cis-abienol on the transcript level of tobacco roots was evaluated using high-throughput sequencing technology. The results showed that the control efficiency of cis-abisol at 60-80 mg/L against tobacco bacterial wilt was 54.50%-57.10%, which was comparable to that of bacteriocin in positive control. The suitable application interval was 3-6 days and 2-3 times. The activities of catalase (CAT), polyphenol oxidase (PPO) and phenylalanine aminolyase (PAL) were significantly increased at 1-6 d after cis-abienol treatment, and the activities of peroxidase (POD) and superoxide dismutase (SOD) were significantly increased at 1-10 d, while the contents of polyphenols and lignin were significantly increased at 3-6 d after cis-abienol treatment. The contents of jasmonic acid (JA) and salicylic acid (SA) were significantly increased at 1-3 d, which cause the up-regulated expression of NtSIPK, NtMEK2, NtMAPK, NtPAL and NtC4H, thereby improving the resistance of tobacco plants against bacterial wilt. Therefore, cis-abienol could be used as bacterial wilt inducers to effectively control the occurrence of tobacco bacterial wilt.