Cloning, Expression And RNA Interference Of Fibroin Light Chain Gene In Ostrinia Furnacalis

Asian corn borer (Ostrinia furnacalis) is one of polyphagous pests,which distributed widely in China. It is also the key insect of corn and cotton. In order to study the physiological basis of Asian Corn spinning, the full-length sequence of fibroin light chain gene (Fib-L) was cloned from Asian corn borer in this paper. And its expressin level in different growing development, under different temperatures and after feeding with different hosts were detected. Additionally, RNAi was used to silence Fib-L in the Asian corn borer by feeding; meanwhile, we achieved some results successfully. The main results of this paper were as follows:1) The full-length sequence of fibroin light chain gene (Fib-L) was successfully cloned from Asian corn borer by RACE. The full-length of Fib-L cDNA was 1098bp. There is an opening reading fragment(ORF) from 39th bp to 830th bp, which encoding 263 amino acid.Its initiation codon is ATG and termination codon is TAA. The Fib-L was about 92.75KDa,and the isoelectric point was 4.99.After the analysis, the amino acids of the gene has 75% identity with Sylepta derogata Fabricius,69%identity with Corcyra cephalonica and 68%identity with Galleria mellonella.2) The expression in different growing development, under different temperatures and after feeding on different hosts were detected by real-time PCR. Results showed that the highest expression level of Fib-L was found in 5th larvae,the second was the 2th larvae; when Ostrinia furnacalis were in the pre-pupa and pupa period, the expression levels was reduced severely.In adulthood, the expression levels was little. We also did the research about the expression levels of Fib-L under different temperatures and after being fed with different hosts.The choosed temperatures were 22?,25?,28?,31?,34?.We found that the highest expression level of Fib-L was under the 34?.In addition, the hosts we choosed were cotton, corn and Persicaria lapathifolia. Results suggested that the highest expression level of Fib-L was fed with cotton, the second was corn.3) Expression level of Fib-L in the larva of Asian corn borer fed with dsRNA was reduced by 34.81%,35.05% compared to the control(CK). With the effect of RNAi on Fib-L, We found that larval duration was shorten significantly, pupal weight and egg laying amount of female also declined significantly than the control. These results indicated that the expression level of Fib-L had an influence on the growth and development of the Asian corn borer.