Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.

<h4>Background</h4>Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Silvia Caccia, Carmen Sara Hernández-Rodríguez, Rod J Mahon, Sharon Downes, William James, Nadine Bautsoens, Jeroen Van Rie, Juan Ferré
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2010
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/2d9ee5aba44647efbc3fb04947493520
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:2d9ee5aba44647efbc3fb04947493520
record_format	dspace
spelling	oai:doaj.org-article:2d9ee5aba44647efbc3fb049474935202021-11-25T06:24:55ZBinding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.1932-620310.1371/journal.pone.0009975https://doaj.org/article/2d9ee5aba44647efbc3fb049474935202010-04-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20376312/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A proteins because of their different mode of action. Their presence is critical in the control of those lepidopteran species, such as Helicoverpa spp., which are not highly susceptible to Cry1A proteins. In Australia, a transgenic variety of cotton expressing Cry1Ac and Cry2Ab (Bollgard II) comprises at least 80% of the total cotton area. Prior to the widespread adoption of Bollgard II, the frequency of alleles conferring resistance to Cry2Ab in field populations of Helicoverpa armigera and Helicoverpa punctigera was significantly higher than anticipated. Colonies established from survivors of F(2) screens against Cry2Ab are highly resistant to this toxin, but susceptible to Cry1Ac.<h4>Methodology/principal findings</h4>Bioassays performed with surface-treated artificial diet on neonates of H. armigera and H. punctigera showed that Cry2Ab resistant insects were cross-resistant to Cry2Ae while susceptible to Cry1Ab. Binding analyses with (125)I-labeled Cry2Ab were performed with brush border membrane vesicles from midguts of Cry2Ab susceptible and resistant insects. The results of the binding analyses correlated with bioassay data and demonstrated that resistant insects exhibited greatly reduced binding of Cry2Ab toxin to midgut receptors, whereas no change in (125)I-labeled-Cry1Ac binding was detected. As previously demonstrated for H. armigera, Cry2Ab binding sites in H. punctigera were shown to be shared by Cry2Ae, which explains why an alteration of the shared binding site would lead to cross-resistance between the two Cry2A toxins.<h4>Conclusion/significance</h4>This is the first time that a mechanism of resistance to the Cry2 class of insecticidal proteins has been reported. Because we found the same mechanism of resistance in multiple strains representing several field populations, we conclude that target site alteration is the most likely means that field populations evolve resistance to Cry2 proteins in Helicoverpa spp. Our work also confirms the presence in the insect midgut of specific binding sites for this class of proteins. Characterizing the Cry2 receptors and their mutations that enable resistance could lead to the development of molecular tools to monitor resistance in the field.Silvia CacciaCarmen Sara Hernández-RodríguezRod J MahonSharon DownesWilliam JamesNadine BautsoensJeroen Van RieJuan FerréPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 5, Iss 4, p e9975 (2010)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Silvia Caccia Carmen Sara Hernández-Rodríguez Rod J Mahon Sharon Downes William James Nadine Bautsoens Jeroen Van Rie Juan Ferré Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
description	<h4>Background</h4>Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A proteins because of their different mode of action. Their presence is critical in the control of those lepidopteran species, such as Helicoverpa spp., which are not highly susceptible to Cry1A proteins. In Australia, a transgenic variety of cotton expressing Cry1Ac and Cry2Ab (Bollgard II) comprises at least 80% of the total cotton area. Prior to the widespread adoption of Bollgard II, the frequency of alleles conferring resistance to Cry2Ab in field populations of Helicoverpa armigera and Helicoverpa punctigera was significantly higher than anticipated. Colonies established from survivors of F(2) screens against Cry2Ab are highly resistant to this toxin, but susceptible to Cry1Ac.<h4>Methodology/principal findings</h4>Bioassays performed with surface-treated artificial diet on neonates of H. armigera and H. punctigera showed that Cry2Ab resistant insects were cross-resistant to Cry2Ae while susceptible to Cry1Ab. Binding analyses with (125)I-labeled Cry2Ab were performed with brush border membrane vesicles from midguts of Cry2Ab susceptible and resistant insects. The results of the binding analyses correlated with bioassay data and demonstrated that resistant insects exhibited greatly reduced binding of Cry2Ab toxin to midgut receptors, whereas no change in (125)I-labeled-Cry1Ac binding was detected. As previously demonstrated for H. armigera, Cry2Ab binding sites in H. punctigera were shown to be shared by Cry2Ae, which explains why an alteration of the shared binding site would lead to cross-resistance between the two Cry2A toxins.<h4>Conclusion/significance</h4>This is the first time that a mechanism of resistance to the Cry2 class of insecticidal proteins has been reported. Because we found the same mechanism of resistance in multiple strains representing several field populations, we conclude that target site alteration is the most likely means that field populations evolve resistance to Cry2 proteins in Helicoverpa spp. Our work also confirms the presence in the insect midgut of specific binding sites for this class of proteins. Characterizing the Cry2 receptors and their mutations that enable resistance could lead to the development of molecular tools to monitor resistance in the field.
format	article
author	Silvia Caccia Carmen Sara Hernández-Rodríguez Rod J Mahon Sharon Downes William James Nadine Bautsoens Jeroen Van Rie Juan Ferré
author_facet	Silvia Caccia Carmen Sara Hernández-Rodríguez Rod J Mahon Sharon Downes William James Nadine Bautsoens Jeroen Van Rie Juan Ferré
author_sort	Silvia Caccia
title	Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
title_short	Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
title_full	Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
title_fullStr	Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
title_full_unstemmed	Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.
title_sort	binding site alteration is responsible for field-isolated resistance to bacillus thuringiensis cry2a insecticidal proteins in two helicoverpa species.
publisher	Public Library of Science (PLoS)
publishDate	2010
url	https://doaj.org/article/2d9ee5aba44647efbc3fb04947493520
work_keys_str_mv	AT silviacaccia bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT carmensarahernandezrodriguez bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT rodjmahon bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT sharondownes bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT williamjames bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT nadinebautsoens bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT jeroenvanrie bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies AT juanferre bindingsitealterationisresponsibleforfieldisolatedresistancetobacillusthuringiensiscry2ainsecticidalproteinsintwohelicoverpaspecies
_version_	1718413731957833728

Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.

Ejemplares similares