摘要 : Gloverin is known to be an inducible antimicrobial peptide. This study reports a gloverin gene (<i>Seglv</i>) identified from the beet armyworm, <i>Spodoptera exigua</i>. <i>Seglv</i> encodes 175 amino acids with a signal peptide.... 展开 Gloverin is known to be an inducible antimicrobial peptide. This study reports a gloverin gene (<i>Seglv</i>) identified from the beet armyworm, <i>Spodoptera exigua</i>. <i>Seglv</i> encodes 175 amino acids with a signal peptide. Its amino acid sequence is highly homologous (>95%) to other known gloverins. <i>Seglv</i> was expressed from egg to adult stages even without immune challenge. Especially, in larval stage, it was expressed in all tested tissues, such as hemocyte, fat body, gut, and epidermis. However, the constitutive expression level was significantly elevated in response to bacterial challenge. Expression of a Toll gene was required for expression of <i>Seglv</i>. A recombinant Seglv protein was synthesized using a bacterial expression system and purified with an affinity chromatography. The recombinant protein showed a specific antibacterial activity against a Gram-positive bacterium, but no activity against a Gram-negative <i>Escherichia coli</i>. Injection of specific double stranded RNA (dsRNA) against <i>Seglv</i> could suppress its expression. Knockdown of <i>Seglv</i> expression induced a significant developmental retardation and resulted in hypotrophy pupae. The larvae treated with dsRNA were much more susceptible to <i>Bacillus thuringiensis</i> than the control larvae. These results suggest that Seglv acts as an antimicrobial peptide especially against Gram-positive bacteria including <i>B. thuringiensis</i>. 收起