Transcriptome Sequencing Of Antheraea Pernyi Larval Integument And Analysis Of Bilin Related Genes

The body color of wild Antheraea pernyi（Lepidoptera）larvae are green.After a long period of natural and artificial selection,the cyan-yellow,yellow,blue and white lineages were developed.In practice,the larval color has always been an important morphological marker in the breeding of oak silkworm.However,the molecular mechanism of the body color differentiation of oak silkworm larvae is rarely studied.So far,there was no report on cloning of the genes related to body color of oak silkworm larvae.Lepidopteran larval green coloration is assembled from blue bile pigment and it is usually associated with proteins in pigment-protein complexes.Bilirubin reductase（BVRB）catalyzes the reduction of biliverdin produced by heme degradation to bilirubin.In this study,the offspring from green larvae（Xuanda）and yellow larvae（Shenhuang）were used,and the green and yellow larvae at day 10 of the fifth instar derived from a F₂hybrid offspring population were chosen.Illumina sequencing platform was used for transcriptome sequencing of integument.The unigenes were annotated functionally by using the GO,COG,eggNOG and KEGG.The body color related genes of oak silkworm were screened based on the annotation results of Nr database.The identification of these genes laid a foundation for the further study of their functions and the molecular mechanism of body color differentiation between green and yellow oak silkworm larvae.The main research results are as follows.1.A total of 9.16 Gb Clean data were acquired from integument transcriptome of green and yellow oak silkworm larvae.The differential expressed unigenes from COG,KEGG,GO and eggNOG were 412,452,590 and 970,respectively.There were 972 differential expressed unigenes in Nr database after being annotated,in which 410 unigenes were up-regulation and562 unigenes were down-regulation.2.A total of 8 biliverdin related genes were obtained,including 5 BBPs,1 apolipoprotein D,1 insecticyanin A-like and 1 BVRB.Three bilin related genes were successfully cloned in this study.The results showed that they were expressed in all tissues and organs of green and yellow oak silkworm larvae.There were significant differences in the expression of ApBBP1and ApBBP2 in integument between green and yellow larvae.Our results suggested that ApBBP1 and ApBBP2 might play a key role in the body color differentiation of green and yellow oak silkworm larvae.3.The results of biliverdin reductase activity analysis showed that the enzyme activities in the hemolymph,silk gland and fat body of the green larvae were higher than those of the yellow larvae,and there was significant different in hemolymph and silk gland between green and yellow larvae.It is speculated that the biliverdin reductase activity in hemolymph may cause the difference of green and yellow body color between the larvae of A.pernyi.