Characterization of two novel heat shock protein 70s and their transcriptional expression patterns in response to thermal stress in adult of Frankliniella occidentalis (Thysanoptera: Thripidae)

Heat shock protein 70 (HSP70) is one of the most important members in the heat shock protein family, and plays important roles in the thermotolerance of insect. To explore the molecular mechanism of thermotolerance of Frankliniella occidentalis adults, the difference in the expression of HSP7Os in F occidentalis male or female adults under the thermal stress was studied under the laboratory conditions. Two full length cDNAs of HSP7Os gene (Fohsc704 and Fohsc705) were cloned from F occidentalis by using RT-PCR and RACE. The genomic sequence was demonstrated by genomic validation, and the position and size of the intron were analyzed by sequence analysis of cDNA. Real-time PCR was used to analyze the HSP70 expression patterns. The cDNA of Fohsc704 and Fohsc705 possessed 2 073 and 1 476 bp which encoded 690 and 491 amino acids (aa) with a calculated molecular weight of 75 and 54 kDa, respectively. Four introns in Fohsc704 and six introns in Fohsc705 protein were found. However, the HSP70 protein sequences in our study were ended with EKKN and GIFL, which were different from the reported FoHSP70s. Various expression patterns of Fohsc704 and Fohsc705 were found in both genders of F occidentalis under thermal stress. The expression of Fohsc704 and Fohsc705 reached to the highest level at -12 and -8 degrees C in male adults, respectively, and Fohsc705 expressed the highest level at 33 degrees C in female adults. In conclusion, HSP7Os of F occidentalis in our study are novel heat shock proteins. There were difference in expression patterns of the two hsc70s in genders of F occidentalis, and the two HSP7Os play important roles in the thermotolerance of F occidentalis.