Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) is a key regulator of antioxidant enzyme genes and modulates responses of mite on resistant vs. susceptible host tree cultivars

The important role of nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) in modulating the expression of detoxification genes has been demonstrated without doubt in several insect pests. However, the function of Nrf2 in regulating antioxidant enzyme (AOE) during plant-insect pest interactions has been scarcely addressed. This study aims to decipher the role of EsNrf2 of six-spotted mite (SSM, Eotetranychus sexmaculatus; Acari: Tetranychidae) in regulating AOEs during SSM-rubber tree interaction. The results showed that treatment with the Nrf2 inhibitor brusatol can inhibit the expression of EsNrf2 and the downstream regulated AOE genes such as superoxide dismutase, catalase and peroxidase (both transcription and enzyme activity), while the chemicals 3H-1, 2-dithiole-3-thione and tert-butylhydroquinone exhibited strong activation to those genes. In addition, Knockdown EsNrf2 by RNA interference (RNAi) also could sufficiently down-regulate AOEs expression. When SSM was pre-treated with chemicals (or double strand RNA) and then fed on mite-resistant rubber cultivar, the inhibition pattern of EsNrf2 and AOEs was magnified, while SSM fed on mitesusceptible rubber cultivar showed normal activation or inhibition pattern. Moreover, inhibition, activation and knockdown the transcription of EsNrf2 decreased the survival rate, fecundity, and hatchability of the SSM up to 50%, depending on treatments and rubber cultivars. The study hints that EsNrf2 is a key regulator of AOE genes in SSM, furthermore, the insights gained in the transcriptional regulation of EsNrf2 during plant-mite interactions could provide novel solutions for controlling this pest.