The Functional Research Of Fatty Acid Desaturase Of Coptotermes Formosanus Shiraki

Coptotermes formosanus,is an insect that is highly dangerous to agriculture and wooden buildings,it contains large amounts of unsaturated fatty acid,further affect the energy metabolism and social behavior of termites,including pheromone synthesis,epidermal formation,energy storage,cold and drought tolerance,etc.Among the many catalytic enzymes involved in the synthesis of fatty acid,fatty acid desaturase plays a key role in the synthesis of unsaturated lipids,is closely related to the synthesis of oleic acid,linoleic acid,and other unsaturated fat in termites.So far,however,the role of Fatty acid desaturase in regulating the composition of various unsaturated fat,as well as the behavior and physiology of termites has not been clearly defined.This study is intended to provide experimental eviences for the role of desaturases in the behavior and physiology of termite C.formosanus.Our result may open a new insight on inter-termite communication and shed light on termite control strategies to future applications.The main findings are as follows:1.7 first desaturase family genes were found from the transcriptome data of whole body of Coptotermes formosanus,by constructing phylogenetic tree,7 desaturase genes were classified into Cfor-desats A1,Cfor-desat A2-a,Cfor-desat A2-b,Cfor-desat B-a,Cfor-desat B-b,Cfor-desat D,Cfor-desat E.The full length of Cfor-desats gene was obtained by gene amplification,the gene structure was analyzed,and the mode of action and function were predicted.The expression levels of the seven Cfor-desats genes in different tissues(head,gut,fat body and cuticle)of workers were detected by real-time RT-PCR.We found that Cfor-desats genes are highly expressed in the cuticle and fat body of C.formosanus,suggesting that desaturase may be involved in the physiological process of synthesis or metabolism of the cuticle of C.formosanus.2.We synthesized seven ds RNA corresponding to the Cfor-desats gene,and carried out RNAi processing on the C.formosanus workers.After 5 days of interference,workers were collected for GC analysis of extracted lipids.It was found that the content of unsaturated fatty acid oleic acid in workers treated with ds Cfor-desat A2-a,ds Cfor-desat A2-b decreased significantly.According to NMDS(non-metric multidimensional scaling)similarity analysis,lipids in workers treated with ds Cfor-desat A2-a,ds Cfor-desat A2-b,ds Cfor-desat B-b changed significantly compared with other groups,and these genes were key enzymes affecting the composition of fatty acids in workers.3.The survival rate of the other six desaturase genes decreased significantly 10 days after gene interference.At the same time,normal soldiers reared with disturbed workers also showed higher mortality rates in the ds Cfor-desat A2-b treatment group.Therefore,desaturase is the key gene of fatty acid synthesis in termites,and its regulated products can be transmitted through social behaviors such as trophallactic among termites.