Pengfei Han1,2, Jiao Han1,2, Min Zhang1,2, Jiqiao Fan2,3, Qitian Gong1,2, Enbo Ma1,2, Jianzhen Zhang1,2. 1. Institute of Applied Biology and College of Life Science, Shanxi University, Taiyuan, China. 2. Shanxi Key Laboratory of Integrated Pest Management in Agriculture, Shanxi, China. 3. Institute of Plant Protection, Shanxi Academy of Agricultural Sciences, Taiyuan, China.
Abstract
BACKGROUND: Entomogenous fungi are important factors in biological control, but innate immunity of insects restricts the efficiency of fungus infection. 20-hydroxyecdysone (20E) is involved in regulating the immune response of insects. Our previous studies have revealed that 20E enhances the expression of antibacterial peptides in the worldwide pest Locusta migratoria. However, the mechanism by which 20E controls innate immunity against entomogenous fungi is still unknown. RESULTS: In the present study, based on the transcriptome of L. migratoria fat bodies challenged by 20E, immulectin-1 (LmIML-1) was screened and identified to be involved in modulating antifungal immunity. Spatio-temporal expression analysis showed LmIML-1 was highly expressed in the fifth instar nymph stage, and mainly distributed in the fat bodies and hemolymph. Both exogenous and endogenous 20E could increase the transcription of LmIML-1. In contrast, transcription of LmIML-1 did not increase when the 20E signal was blocked by RNAi of LmEcR (ecdysone receptor). The expressed recombinant protein rLmIML-1 possessed agglutination activity and promoted the encapsulation. RNA interference of LmIML-1 reduced the encapsulation of hemocytes, decreased the antifungal activity of plasma against Metarhizium anisopliae and accelerated the death of nymphs under the stress of entomogenous fungus. Meanwhile, 20E did not increase the antifungal activity with silence of LmIML-1 in L. migratoria. CONCLUSION: 20E enhances antifungal immunity by activating immulectin-1 in L. migratoria. Our findings indicate a potential mechanism of 20E systematically regulating innate immune response to resist pathogens and provide a well-defined molecular target for improving biological control.
BACKGROUND: Entomogenous fungi are important factors in biological control, but innate immunity of insects restricts the efficiency of fungus infection. 20-hydroxyecdysone (20E) is involved in regulating the immune response of insects. Our previous studies have revealed that 20E enhances the expression of antibacterial peptides in the worldwide pest Locusta migratoria. However, the mechanism by which 20E controls innate immunity against entomogenous fungi is still unknown. RESULTS: In the present study, based on the transcriptome of L. migratoria fat bodies challenged by 20E, immulectin-1 (LmIML-1) was screened and identified to be involved in modulating antifungal immunity. Spatio-temporal expression analysis showed LmIML-1 was highly expressed in the fifth instar nymph stage, and mainly distributed in the fat bodies and hemolymph. Both exogenous and endogenous 20E could increase the transcription of LmIML-1. In contrast, transcription of LmIML-1 did not increase when the 20E signal was blocked by RNAi of LmEcR (ecdysone receptor). The expressed recombinant protein rLmIML-1 possessed agglutination activity and promoted the encapsulation. RNA interference of LmIML-1 reduced the encapsulation of hemocytes, decreased the antifungal activity of plasma against Metarhizium anisopliae and accelerated the death of nymphs under the stress of entomogenous fungus. Meanwhile, 20E did not increase the antifungal activity with silence of LmIML-1 in L. migratoria. CONCLUSION: 20E enhances antifungal immunity by activating immulectin-1 in L. migratoria. Our findings indicate a potential mechanism of 20E systematically regulating innate immune response to resist pathogens and provide a well-defined molecular target for improving biological control.
Authors: Marta Napierała; Joanna Nawrot; Justyna Gornowicz-Porowska; Ewa Florek; Arletta Moroch; Zygmunt Adamski; Anna Kroma; Izabela Miechowicz; Gerard Nowak Journal: Int J Environ Res Public Health Date: 2020-09-04 Impact factor: 3.390