Cloning And Expression Of Heat Shock Protein Genes (Hsp70and Hsp90) Of Propylea Japonica (Coleoptera:Coccinellidae)

Propylaea japonica (Thunberg) is an important predatory natural enemy, as global warming intensifies, summer temperatures generate high temperature stress on natural enemies, and P. japonica has a strong heat resistance, is the dominant species of ladybugs in the field. To explore the heat tolerance mechanism of P. japonica is of great significance to promote the introduction of ladybugs, breeding and applications in high temperature environment. Heat shock proteins (hsps) are rapidly synthesized in response to environmental stressors and improve cell tolerance of stressors, to maintain the normal performance of the body’s physiological activities. Two full-length cDNAs of heat shock protein (hsp) genes (pjhsp90and pjhsp70) were cloned from the P. japonica and their expression was investigated in relation to environmental stressors by the Real-time PCR. The main results are as follows:1. The full length cDNA of pjhsp70-2is2292bp (GenBank accession No.:KJ483960), containing a1959bp open reading frame, a87bp5’un-translate region, a246bp3’un-translate region. Encoding644amino acid with a predicted molecular mass of71.30kDa.2. The full length cDNA of pjhsp90is2471bp (GenBank accession No.:KF792063), containing a2151bp open reading frame, a114bp5’un-translate region, a206bp3’un-translate region. Encoding716amino acid with a predicted molecular mass of81.84kDa.3. The expression levels of hsp70and hsp90mRNA in different instar of P. japonica stressed by high temperatures. The result showed that high temperature could induce pjhsp70-2and pjhsp90genes expression in P. japonica and the expression level was increased along with the development, but the pjhsp70-1gene was not be induced significantly. The four instar larvae was treated in different time. After pretreatment of39℃, then44℃short-term heat shock10min, pjhsp70-2and pjhsp90expressions decreased compared with treatment group, and with the treatment time longer, the extent of the decline gradually increased. From the molecular level to explain high-temperature acclimation can increase the survival rate of P. japonica in lethal high temperatures, further improve heat resistance of P. japonica.4. Imidacloprid stress could induce pjhsp70-1, pjhsp70-2and pjhsp90genes expression and their expression patterns were very similar. With the concentration of imidacloprid, their expression quantity show a downward trend after rising first.When the concentration was 10mg/L,the expression levels were not significantly induced(P>0.05). The concentration was1Omg/L, expression of pjhsp70-1and pjhsp90genes reached the maximum, were8.78fold as high as that of the control (P<0.05). When the concentration was90mg/L, the expression of pjhsp70-2reached the maximum value.