Effect of Jasmonic Acid and Ethylene Mediate Faba Bean Defense Responses to the Activity and Gene Expression of the Detoxifying Enzyme in Frankliniella Occidentalis

Frankliniella occidentalis is an important pest globally and causing serious damage to vegetables and flowers. Exogenous phytohormones can induce host plant resistance and reduce loss caused by pests. This study investigated the effects of detoxification enzyme activity and related gene expression in F. occidentalis after feeding on jasmonic acid (JA)- and ethylene (ET)-cotreated faba bean plants. Change in MFO activity was nonsignificant at 6 and 48 h after F. occidentalis fed on the cotreated faba bean plants; but significantly decreased at 24 h compared with control group. The peak activities of carboxylesterase (CarE) and glutathione S-transferase (GSTs) at 48 h showed a significant increase of 2.31-fold and 1.15-fold, respectively. Additionally, CarE and GSTs activities remained consistent and significantly higher than those of the control group at the remaining timepoints. The expression levels of the P450 genes CYP4-3, CYP6-2, and CYP6-3 in F. occidentalis were significantly upregulated at 6 h and those of CYP6-2 and CYP4-5 were significantly upregulated at 24 h. The expression of the CarE gene CL4503.Conting2 was significantly upregulated at 6 and 48 h that of the GSTs gene FoGSTd1 was significantly upregulated at 24 and 48 h, that of FoGSTs1 was significantly upregulated at all three timepoints, and that of GSTs1 was only significantly upregulated at 6 h and significantly downregulated at 24 and 48 h. These results indicate that F. occidentalis can adjust the activity and gene expression of detoxification enzymes to adapt to the defense response of faba bean induced by JA and ET.