Abstract: 【Aim】To explore the role of heat shock protein Hsp70 genes of Myzus persicae in response to high and low temperature stress. 【Methods】 RT-qPCR was used to detect the relative expression levels of eight MpHsp70 genes (MpHsp70-1, MpHsp70-2, MpHsp70A1, MpHsp70B2, MpHsp68a, MpHsp68b, MpHsc70-4 and MpHsp70) in different wingless adult tissues (head, midgut, embryo and cuticle) and wingless adults under high temperature (36 ℃) and low temperature (4 ℃) stress for different duration (0, 30, 60, 90, 120 and 150 min), respectively. RNAi was used to silence two key MpHsp70 genes (MpHsp70A1 and MpHsp68a), and the survival rate and number of nymphs produced of wingless adults were observed and calculated at 120 min under high temperature treatment (36 ℃) and 30 min under low temperature treatment (4 ℃).【Results】 The eight MpHsp70 genes were expressed in different wingless adult tissues of M. persicae, and the expression levels of MpHsp70, MpHsp70A1, MpHsp70B2, MpHsc70-4 and MpHsp68b in the cuticile were significantly higher than those in the other tissues. The expression levels of MpHsp70-1, MpHsp70-2 and MpHsp68a in the embryo of M. persicae were significantly higher than those in other tissues. High and low temperature stress had significant induction effect on the expression of MpHsp70 genes in wingless adult of M. persicae. The expression levels of MpHsp70-1, MpHsp70A1, MpHsp70-2, MpHsp68a and MpHsp68b all increased and then decreased under 4 ℃ stress, and reached the highest at 30 min under 4 ℃ stress, which were significantly higher than those of the control. Under 36 ℃ stress, the expressions levels of MpHsp70-1, MpHsp70A1, MpHsp70-2, MpHsc70-4, MpHsp68a and MpHsp68b increased first and then decreased. The expression level of MpHsp70-1 reached the highest at 60 min after 36 ℃ stress, and those of the other genes reached the highest at 120 min after 36 ℃ stress. After the silence of MpHsp68a, the survival rate and number of nymphs produced of M. persicae under high and low temperature stress were significantly decreased and those after the silence of MpHsp70A1 under high temperature stress were extremely significantly decreased as compared with those of the control group. 【Conclusion】MpHsp70 genes of M. persicae can respond to high and low temperature stress, and play an important role in the molecular mechanism of resistance to temperature stress of M. persicae.
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Key words: Myzus persicae, Hsp70, environmental stress, gene expression, gene function