Characterization of heat shock protein 70 transcript from Nilaparvata lugens (Stal): Its response to temperature and insecticide stresses

The brown planthopper, Nilaparvata lugens, possesses a strong adaptability to extreme temperature and insecticide stresses. Heat shock proteins (Hsps) are highly conserved molecular chaperones and play a pivotal role in response to various environmental stresses in insects. However, little is known about the response of Hsps to stresses in N. lugens. In the present study, an inducible Hsp70 (NIHsp70) was isolated from this insect and transcriptional expression patterns of NIHsp70 under temperature and insecticide stresses were analyzed. The full-length of NIHsp70 was 2805 bp with an open reading frame (ORF) of 1896 bp, showing high homology to its counterparts in other species. Expression of NIHsp70 was not altered by heat shock for 1 h, nor following recovery from thermal stress. Conversely, decreased expression of NIHsp70 was observed in response to cold shock. In addition, the expression of NIHsp70 increased after imidacloprid exposure. RNA interference experiment combined with insecticide injury assay also demonstrated that NIHsp70 was essential for resistance against insecticide exposure. These observations indicated that NIHsp70 was an important gene involved in the resistance or tolerance to environmental stresses in N. lugens. Interestingly, weak changes in mRNA expression levels of two thermal-inducible Hsp genes, NIHsp90 and NIHsc70 were observed in imidacloprid-exposed N. lugens adults, suggesting that different Hsps may respond differential to the extreme temperature and insecticide stresses. (C) 2017 Elsevier Inc. All rights reserved.