关键词:  大螟, HSC70, 克隆, 表达模式, 荧光定量PCR

Abstract: 【Aim】 In recent years, the pink borer, Sesamia inferens (Walker) has become one of the major pests of rice with its damage increasing. With the global warming, it is further dispersing northward. Heat shock protein 70 (HSP70) family is of great significance for the correct fold and transmission of proteins in organisms. HSP70 participates in growth and development of organisms as chaperones, and causes responses to external stimuli. Our study aims to understand the expression differences of HSC70 gene from S. inferens in different tissues, in different developmental stages and under low-temperature stress, and to explore the molecular mechanisms of environmental adaptability of S. inferens. 【Methods】 RT-PCR and RACE were used to clone the full-length cDNA of HSC70 gene from the 5th instar larvae of S. inferens. The genomic sequence was demonstrated by genomic validation and intron was analyzed by sequence analysis of cDNA. The expression patterns of HSC70 gene were investigated by real-time quantitative PCR. 【Results】 The complete cDNA sequence was obtained and named as Sihsc70 (GenBank accession no.: KJ639908), which is 2 160 bp in length, containing an opening reading frame (ORF) of 1 962 bp and encoding 653 amino acid residues with the predicted molecular weight of 71.6 kDa. Three conserved sequences of HSP70 family exist in its amino acid sequence. The cytoplasmic localization signal in C-terminus indicated that S. inferens HSC70 is a cytoplasmic heat shock protein. Analysis of genomic DNA sequence (GenBank accession no.: KJ639909) demonstrated that HSC70 gene contains 2 introns. The 1st intron, 685 bp in length, is located upstream of the coding region. The 2nd intron, 803 bp in length, is located in the coding region. The expression levels of Sihsc70 were not significantly different among different tissues of the 5th instar larva (P＞0.05), with the higher expression levels in midgut, hindgut and epidermis, and the lowest in salivary glands. Sihsc70 had the lowest expression level in female adults, and higher expression levels in eggs, 2nd and 5th instar larvae, which were 6.33-, 3.21- and 1.86-fold as high as that in female adults, respectively. Compared with the control group (27℃), low-temperature stress had no significant effect on the expression of Sihsc70 in the 5th instar larvae (P>0.05). 【Conclusion】 The results suggest that Sihsc70 has different expression levels in different developmental stages and different larval tissues, and low-temperature stress would not induce high expression of this gene.  

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