Characterization of heat shock cognate protein 70 gene and its differential expression in response to thermal stress between two wing morphs of Nilaparvata lugens (Stal)

Previous studies have demonstrated differences in thermotolerance between two wing morphs of Nilaparvata lugens, the most serious pest of rice across the Asia. To reveal the molecular regulatory mechanisms underlying the differential thermal resistance abilities between two wing morphs, a full-length of transcript encoding heat shock cognate protein 70 (Hsc70) was cloned, and its expression patterns across temperature gradients were analyzed. The results showed that the expression levels of N1Hsc70 in macropters increased dramatically after heat shock from 32 to 38 degrees C, while N1Hsc70 transcripts in brachypters remained constant under different temperature stress conditions. In addition, N1Hsc70 expression in the macropters was significantly higher than that in brachypters at 1 and 2 h recovery from 40 degrees C heat shock. There was no significant difference in N1Hsc70 mRNA expression between brachypters and macropters under cold shock conditions. Therefore, N1Hsc70 was indeed a constitutively expressed member of the Hsp70 family in brachypters of N. lugens, while it was heat-inducible in macropters. Furthermore, the survival rates of both morphs injected with N1Hsc70 dsRNA were significantly decreased following heat shock at 40 degrees C or cold shock at 0 degrees C for 1 h. These results suggested that the up-regulation of N1Hsc70 is possibly related to the thermal resistance, and the more effective inducement expression of NIHsc70 in macropters promotes a greater thermal tolerance under temperature stress conditions. (C) 2016 Elsevier Inc. All rights reserved.