Abstract: Chitin synthase 1（CHS1）is a crucial enzyme in chitin synthesis and plays a key role in the chitin formation in insect tissues. In order to explore the gene structure and function of Sogota furcifera chitin synthase 1（SfCHS1）,transcriptome sequencing combined with PCR amplification technology were employed to study the structure characteristic of SfCHS1 gene,then quantitative PCR technology to study the spatio-temporal expression characteristics of of SfCHS1 gene,and the method of micro injection of RNAi to study the RNAi efficiency of SfCHS1 gene. The SfCHS1 cDNA contained an open reading frame of 4 719 bp and encoded 1 572 amino acids with the putative molecular weight of 180.6 kD. Homology analysis indicated that SfCHS1 included 6 N-glycosylation sites and 16 transmembrane helixes. In addition,2 transcripts（CHS1a and CHS1b）resulting from exclusively alternative splicing were identified in S. furcifera by PCR amplification and sequencing.Phylogenetic analysis suggested that SfCHS1 shared 97% identity with the known CHS1（Laodelphgax striatellus and Nilaparvata lugens）. The analysis of temporal expression characteristics showed that SfCHS1 was most highly expressed in the first day of every instar. SfCHS1 was mainly expressed in epidermis and then in trachea,a little in gut. Efficient silencing of the SfCHS1 gene through micro injection of RNAi led to rapid and significant reduction levels of SfCHS1 mRNA and resulted in S. furcifera deaths. This study suggests that SfCHS1cDNA has two variants（SfCHS1a and SfCHS1b）,and SfCHS1 is highly expressed in chitin biosynthesis stages and tissues. RNAi injection-based significantly reduces the expression level of SfCHS1 gene and causes their high-rate deaths.

Key words: Sogota furcifera, chitin synthase 1, alternative splicing, expression character, RNAi