Identification of a heat shock protein 90 gene involved in resistance to temperature stress in two wing-morphs of Nilaparvata lugens (Stål).

The brown planthopper, Nilaparvata lugens, is one of the most destructive pests damaging rice in Asia and exhibits wing dimorphism, with brachypters possessing severely reduced wings and macropters bearing fully developed wings. Previous studies have shown that macropters are more heat resistant than brachypters. To understand the molecular mechanism underlying the differential thermotolerance abilities of these two morphs, a full-length Hsp gene, NlHsp90 was cloned from N. lugen. Our results showed that the relative expression levels of NlHsp90 in N. lugens females increased with the rise of temperature. Interestingly, NlHsp90 in macropters females could be induced at lower temperature (32°C) than that in brachypters (34°C), and the NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 34 to 40°C. In addition, the maximum expression levels of NlHsp90 were achieved much earlier in macropters, and NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 1 to 6h of recovery after temperature stress. Furthermore, knockdown of NlHsp90 by dsRNA injection reduced survival in both morphs with a greater reduction in the macropters relative to that of the brachyters. These results indicated that NlHsp90 plays an important role for thermotolerance in N. lugens, and there is difference on induction between two morphs.