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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #321193

Research Project: Genetic Improvement of Maize and Sorghum for Resistance to Biotic Stress

Location: Crop Genetics and Breeding Research

Title: APN1 is a functional receptor of Cry1Ac but not Cry2Ab in Helicoverpa zea

Author
item WEI, JIZHEN - Institute Of Plant Protection - China
item ZHANG, MIN - University Of Arizona
item LIANG, GEMEI - Institute Of Plant Protection - China
item WU, KONGMING - Institute Of Plant Protection - China
item GUO, YUYUAN - Institute Of Plant Protection - China
item Ni, Xinzhi
item LI, XIANCHUN - Institute Of Plant Protection - China

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2015
Publication Date: 1/12/2016
Citation: Wei, J., Zhang, M., Liang, G., Wu, K., Guo, Y., Ni, X., Li, X. 2016. APN1 is a functional receptor of Cry1Ac but not Cry2Ab in Helicoverpa zea. Scientific Reports. 6:19179.

Interpretive Summary: Insect midgut enzyme aminopeptidases N (APNs) in caterpillars are divided into eight clusters, designated as APN1-8. Although APN1 has been implicated as one of the receptors for Bt toxin 1 (Cry1Ac) in several species, its potential role in the mode of action of another Bt toxin 2 (Cry2Ab) has not been functionally determined so far. To test whether APN1 also acts as one of the receptors for Bt toxin 1 in corn earworm and even for Bt toxin 2 in this species, we conducted two function analyses. The first was a gain of function analysis by differentially expressing corn earworm enzyme APN1 in the midgut and fat body cell lines of corn earworm and the ovarian cell line of fall armyworm. The second was a loss of function analysis by silencing of the endogenous APN1 using RNA interference technology in the three cell lines using corn earworm APN1 double strand RNA. The first analysis showed that differential expression of corn earworm APN1 significantly increased the susceptibility of the three cell lines to Bt toxin 1, but had no effect on their susceptibility to Bt toxin 2. Knocking down of the endogenous APN1 made the three cell lines resistant to Bt toxin 1, but didn’t change cell lines’ susceptibility to Bt toxin 2. The findings from this study demonstrate that corn earworm APN1 is a functional receptor of Bt toxin 1, but not Bt toxin 2.

Technical Abstract: Lepidopteran midgut aminopeptidases N (APNs) are phylogenetically divided into eight clusters, designated as APN1-8. Although APN1 has been implicated as one of the receptors for Cry1Ac in several species, its potential role in the mode of action of Cry2Ab has not been functionally determined so far. To test whether APN1 also acts as one of the receptors for Cry1Ac in Helicoverpa zea and even for Cry2Ab in this species, we conducted a gain of function analysis by heterologously expressing H. zea APN1 (HzAPN1) in the midgut and fat body cell lines of H. zea and the ovarian cell line of Spodoptera frugiperda (Sf9) and a loss of function analysis by RNAi (RNA interference) silencing of the endogenous APN1 in the three cell lines using the HzAPN1 double strand RNA (dsRNA). Heterologous expression of HzAPN1 significantly increased the susceptibility of the three cell lines to Cry1Ac, but had no effects on their susceptibility to Cry2Ab. Knocking down of the endogenous APN1 made the three cell lines resistant to Cry1Ac, but didn’t change cell lines’ susceptibility to Cry2Ab. The findings from this study demonstrate that HzAPN1 is a functional receptor of Cry1Ac, but not Cry2Ab.