Korean Journal of Agricultural Science ISSN:2466-2402(Print) 2466-2410(Online) 농업과학연구

Random genes were screened in two transforming ways to investigate the new genes of a ladybug using the Harmonia axyridis cDNA library stock cell cloned in the LITMUS 28i vector in a previous study. Phenotypic variation was observed after injection of the synthesized double-stranded RNA through the in vitro transcription process. The cDNA library of H. axyridis was transformed into E. coli DH5α and 10B competent cells by heat shock. Analysis of the nucleotide sequences of the 42 clones with the insert DNAs revealed that 21 clones were homologous with the genes of insects, and only one clone had a gene from H. axyridis. Thirteen of the 21 insect genes were homologous with genes from coleopteran insects. Fourteen genes were selected, which were identified by the gene screening results, and were synthesized as double-stranded RNA through in vitro transcription. One microgram of the synthesized double-stranded RNA between segments T1 and T2 were injected using a syringe into each anesthetized fourth larvae which were under 2 days old. As a result, a phenotypic variation appeared in the larva injected with the two genes. While the eggs of H. axyridis injected with distilled water hatched out three days after oviposition, the eggs of H. axyridis injected with dsHma 06 did not hatch but become shrivel a week after oviposition. Most of the H. axyridis injected with dsHma 08 died and were unable to complete the pupation or eclosion during ecdysis.