Expression of four antimicrobial peptide genes in Bombyx mori infected with Beauveria bassiana

ObjectiveThe present study was conducted to evaluate response pattern of antimicrobial peptides in Bom-byx mori against Beauveria bassiana infection in order to provide beneficial reference for researches on antifungal mecha-nism of B. mori and other lepidoptera insects. MethodThe expression patterns of antimicrobial peptide genes cecropinA, gloverin2, lebocin1/2 and lysozyme in B. mori after being infected with B. bassiana were detected using real-time fluores-cence quantitative PCR. The differential expressions of the four antimicrobial peptide genes in fat body, hemolymph, malpighian tubule and midgut at different time points were compared. ResultAfter being induced by B. bassiana, the expression of cecropinA was up-regulated by 10.2 times to the maximum in fat body and 13.2 times to maximum in hemolymph. The expression of cecropinA was also significantly up-regulated in malpighian tubule at early stage of the in-fection ( P<0 . 05 , the same below ) , and in midgut at middle-late stages of the infection . Up-regulated expression of gloverin2 occurred twice in fat body and the maximum re-regulated expression multiple was 15.7 times. The expression of gloverin2 up-regulated in hemolymph at earlier stage but down-regulated in malpighian tubule. It also up-regulated in mindgut after 16-48 hours of infection, with maximum up-regulated multiples reaching 6.7 times. The expression of lebocin1/2 up-regulated in fat body by 19.4 times to utmost limit and by 22.4 times to the maximum in hemolymph. It also up-regulated significantly in malpighian tubule after 16 hours of infection and in midgut after 24-48 hours of infection. The expression of lysozyme significantly up-regulated in fat body, and also significantly up-regulated in hemolymph and malpighian tubule at earlier stage of infection. But the expression in midgut showed no obvious regulation . ConclusionThe expressions of antimicrobial peptide genes cecropinA, gloverin2, lebocin1/2 and lysozyme up-regulated to differ-ent extents after B. mori infected by B. bassiana, especially in fat body and hemolymph of B. mori. The results suggest that cecropinA, gloverin2, lebocin1/2 and lysozyme may play important roles in B. mori antifungal process against B. bassiana infection.