Identification and preliminary function exploration of tyrosine decarboxylase gene in vitellogenin deposits of Propylea japonica
[Objective]The aim of this study is to analyze the structural and molecular characteristics of Propylea japonica tyrosine decarboxylase(TDC)genes,and their expression pattern and to explore their regulatory role as a key octopamine synthetase gene in the reproductive development of ladybird beetle.[Methods]Four PjTDC genes and their basic structural characteristics were identified by bioinformatics software.PjTDC1 gene was cloned by polymerase chain reaction.The expression pattern of PjTDC1 gene in different tissues and at different developmental stages were investigated by quantitative real-time polymerase chain reaction.And the function of PjTDC1 gene in P.japonica were studied by RNA interference techniques.[Results]There were four TDC genes in the P.japonica,which were named PjTDC 1-4.All the TDC proteins of P.japonica have PLN02880 domain,and PjTDC1 gene has an open reading frame of 1 728 bp,encoding 575 amino acid residues.PjTDC1 protein has the highest homology with the TDC protein of Cylas formicarius.PjTDC1 gene was expressed in P.japonica at different developmental stages,with the highest expression level in the 1st instar larvae but lower expression level in the egg stage larvae,the 4th instar larvae,and 7-day-old female adults.Generally speaking,the expression level of PjTDC1 decreased gradually at larval stages and in the adults after eclosion for 1 to 7 days.PjTDC1 gene is also expressed in different tissues,but it is mainly expressed in the ovaries,dorsal cuticula and head of the 5-day-old female adults.The results of RNA interference experiment showed that silencing of PjTDC1 gene inhibited the deposition of vitellogenin in the oocytes of P.japonica.In addition,on the 1st and 3rd day after injection of double strand RNA,the width of primary oocytes in the treatment group was significantly 10.03％and 18.60％lower than that in the control group.These results suggest that PjTDC1,as a key gene for octopamine synthesis,also plays an important regulatory role in the reproductive development of P.japonica.[Conclusion]In this study,the basic structural features of PjTDC genes and the spatial and temporal expression pattern of PjTDC1 at different developmental stages and in different tissues of P.japonica were studied,and its positive regulatory role in the process of vitellogenin deposits in the oocytes of P.japonica were clarified,which will provide theoretical basis for further solving the problem of large-scale artificial propagation of P.japonica.
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