Identification and Expression Patterns of Three Vitellogenin Genes and Their Roles in Reproduction of the Alligatorweed Flea Beetle (Coleoptera: Chrysomelidae).

The alligatorweed flea beetle is an insect used for biological control of the aquatic weed (alligatorweed). Because these insects are oviparous, synthesis, and transportation of yolk proteins is integral to reproduction. Vitellin, the chief protein constituent in egg yolk, is mainly synthesized in the fat body and its synthesis is regulated by the transcript levels of (). In our study, we first cloned and characterized three genes from and quantified the expression levels of these in different tissues and developmental stages by RT-qPCR. Analysis of the full-length cDNA sequences of the three genes revealed that the open reading frames of , , and were 5175, 5346, and 5385 bp, encoding 1724, 1781, and 1794 amino acids, respectively. RT-qPCR analysis revealed that these three have similar expression patterns; expression in the fat body was significantly higher than that in other tissues, and the highest expression was observed in the adult developmental stage. RNA interference was used to explore the functions of the . female adults injected with dsRNA targeting the genes showed decreased gene expression. Down regulation of all three significantly affected ovary development, reduced egg laying capacity, and reduced the egg hatch rate compared with the control groups. Our findings provide the basis for further study of the functions of genes in other insect species.