Expression Profile Of Cuticular Protein Genes CPR97 And CPR63 Between The Pupal Melanic Strain And The Wild Strain Of Spodoptera Exigua

Insect cuticle is composed primarily of chitin and cuticular proteins. It is believed that the cuticular proteins are the main reason of the physical properties of cuticle.The beet armyworm Spodoptera exigua(Hübner) is a worldwide pest that can feed on many kinds of host plant. Beet armyworm has a wide distribution in our country and has caused heavy losses in recent years. Pupal melanic strain of beet armyworm occurred in our laboratory at normal conditions in the wild strain mutation, and the pupal melanic strain keeps stable traits which has no separation.In this study, we choose the cuticula of 5th instar, late-prepupa and early-pupa of the two strains to do RNA-seq, and the main results are as follows:The total reads of 5th instars, prepupa and pupa in the wild strain is 7157837,7079779 and 7079779 with 350734013 bp,346909171bp and 345310840 bp. In the pupal melanic strain the numbers of reads are 7397772, 7188944, 7305754 with 362490828 bp, 352258256 bp, 357981946 bp. And the total mapped reads almost are 75% with the least of 65.35%.There are 7257 genes are up-regualted in pupal melanic strain and 664 genes down-regualted compared with the wild strain in the 5th instars. 460 genes are up-regualted and 439 are genes down-regualted in late-prepupa. The number of up-regulated genes in early-pupa is 162 and down-regulated is 293.After screening of differentially expressed genes at the three stages, we find many insect cuticular protein genes. 9 cuticular protein genes are up-regulated in prepupa with the biggest fold of 23.6, and only one cuticular protein genes is down-regulated with the fold of 21.2. 5 cuticular protein genes are up-regulated in pupa with the biggest fold 210.3.Real time PCR result as follows, the CPR97 gene was up-regulated in SEM at both late-prepupa and early-pupa development stages. CPR63 was up-regulated at early-pupa stage.