Insect Resistance to Bacillus thuringiensis

Candas, Mehmet; Loseva, Olga; Oppert, Brenda; Kosaraju, Pradeepa; Bulla, Lee A.

doi:10.1074/mcp.m200069-mcp200

Cited by 107 publications

(19 citation statements)

References 67 publications

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“…Failure to detect them may be due to the under-representation or absence of integral membrane proteins in 1-D or 2-D gels used in ligand binding studies with labelled toxin [55], [56]. Failure to isolate them could be due to the general difficulty of isolating membrane proteins.…”

Section: Discussionmentioning

confidence: 99%

An ABC Transporter Mutation Is Correlated with Insect Resistance to Bacillus thuringiensis Cry1Ac Toxin

et al. 2010

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Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt) are commercially successful in reducing pest damage, yet knowledge of resistance mechanisms that threaten their sustainability is incomplete. Insect resistance to the pore-forming Cry1Ac toxin is correlated with the loss of high-affinity, irreversible binding to the mid-gut membrane, but the genetic factors responsible for this change have been elusive. Mutations in a 12-cadherin-domain protein confer some Cry1Ac resistance but do not block this toxin binding in in vitro assays. We sought to identify mutations in other genes that might be responsible for the loss of binding. We employed a map-based cloning approach using a series of backcrosses with 1,060 progeny to identify a resistance gene in the cotton pest Heliothis virescens that segregated independently from the cadherin mutation. We found an inactivating mutation of the ABC transporter ABCC2 that is genetically linked to Cry1Ac resistance and is correlated with loss of Cry1Ac binding to membrane vesicles. ABC proteins are integral membrane proteins with many functions, including export of toxic molecules from the cell, but have not been implicated in the mode of action of Bt toxins before. The reduction in toxin binding due to the inactivating mutation suggests that ABCC2 is involved in membrane integration of the toxin pore. Our findings suggest that ABC proteins may play a key role in the mode of action of Bt toxins and that ABC protein mutations can confer high levels of resistance that could threaten the continued utilization of Bt–expressing crops. However, such mutations may impose a physiological cost on resistant insects, by reducing export of other toxins such as plant secondary compounds from the cell. This weakness could be exploited to manage this mechanism of Bt resistance in the field.

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Section: Discussionmentioning

confidence: 99%

An ABC Transporter Mutation Is Correlated with Insect Resistance to Bacillus thuringiensis Cry1Ac Toxin

et al. 2010

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“…The B subunit is non-catalytic, whereas the A subunit is catalytic for ATP hydrolysis. The findings of two-dimensional difference gel electrophoresis validated that the expression of V-ATPase subunit B was enhanced in the midgut of Bt-resistant and -susceptible P. interpunctella larva (Candas et al, 2003). In the present study, transcriptional analysis of hpvaa in different tissues of H. parallela larval revealed that the highest expression level was in Malpighian tubules while the lowest expression was in fat body.…”

Section: Discussionmentioning

confidence: 63%

“…In recent years, research has shown that V-ATPase A and B subunits are the binding proteins of Cry1Ac protein in Heliothis virescens, Plodia interpunctella (Candas et al, 2003), and Helicoverpa armigera (Chen et al, 2010). The B subunit is non-catalytic, whereas the A subunit is catalytic for ATP hydrolysis.…”

Section: Discussionmentioning

confidence: 99%

Characterization of a novel Cry8Ea3-binding V-ATPase Subunit A in Holotrichia parallela

et al. 2016

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ABSTRACT. Several receptor proteins of Cry toxin have been previously identified, including cadherin-like, aminopeptidase N, and alkaline phosphatase. In the present work, a novel binding protein, V-ATPase subunit A (HpVAA), was identified in Holotricia parallela larvae and characterized. We performed reverse transcriptionpolymerase chain reaction and rapid amplification of cDNA ends technology to obtain the cDNA of the full-length hpvaa. Sequencing analysis showed that the open reading frame of hpvaa (GenBank accession No. KU497557) is 1845 bp long, encoding 614 amino acid residues. The predicted molecular weight and isoelectric point of HpVAA were 67.85 kDa and 4.9, respectively. The HpVAA protein, which includes two putative conserved domains, ATP-synt_ab_N and ATP-synt_ab_C, and a Walker A (GAFGCGKT) motif and a Walker B (SMMAD) motif, possesses the same structural characteristics as V-ATPase subunit A from other insects. The protein was successfully 2 W. Wei et al. Genetics and Molecular Research 15 (3): gmr.15038994 expressed in Escherichia coli, and a ligand blot assay showed binding of the protein with Cry8Ea3 toxin. Transcriptional analysis of hpvaa in different tissues of H. parallela larvae was performed by qRT-PCR, which showed that the relative expression of hpvaa in the Malpighian tubules is higher than that in other tissues.

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“…V-ATPase in the insect midgut mediates pH to create an alkaline environment and participates in ion-transport processes29. V-ATPase up-regulation has been found to be related to Cry1Ac resistance in Plodia interpunctella and P. xylostella 3031. Although V-ATPase has been identified as a Cry toxin-binding protein in H. virescens (Cry1Ac), H. armigera (Cry1Ac) and O. furnacalis (Cry1Ab)323334, little is known about its function with regard to Cry toxins in other insects.…”

Section: Discussionmentioning

confidence: 99%

Proteomic analysis of Cry2Aa-binding proteins and their receptor function in Spodoptera exigua

Qiu

Zhang

et al. 2017

Sci Rep

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The bacterium Bacillus thuringiensis produces Crystal (Cry) proteins that are toxic to a diverse range of insects. Transgenic crops that produce Bt Cry proteins are grown worldwide because of their improved resistance to insect pests. Although Bt “pyramid” cotton that produces both Cry1A and Cry2A is predicted to be more resistant to several lepidopteran pests, including Spodoptera exigua, than plants that produce Cry1Ac alone, the mechanisms responsible for the toxicity of Cry2Aa in S. exigua are not well understood. We identified several proteins that bind Cry2Aa (polycalin, V-ATPase subunits A and B, actin, 4-hydroxybutyrate CoA-transferase [4-HB-CoAT]), and a receptor for activated protein kinase C (Rack), in S. exigua. Recombinant, expressed versions of these proteins were able to bind the Cry2Aa toxin in vitro assays. RNA interference gene knockdown of the Se-V-ATPase subunit B significantly decreased the susceptibility of S. exigua larvae to Cry2Aa, whereas knockdown of the other putative binding proteins did not. Moreover, an in vitro homologous competition assay demonstrated that the Se-V-ATPase subunit B binds specifically to the Cry2Aa toxin, suggesting that this protein acts as a functional receptor of Cry2Aa in S. exigua. This the first Cry2Aa toxin receptor identified in S. exigua brush-border membrane vesicles.

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Insect Resistance to Bacillus thuringiensis

Cited by 107 publications

References 67 publications

An ABC Transporter Mutation Is Correlated with Insect Resistance to Bacillus thuringiensis Cry1Ac Toxin

An ABC Transporter Mutation Is Correlated with Insect Resistance to Bacillus thuringiensis Cry1Ac Toxin

Characterization of a novel Cry8Ea3-binding V-ATPase Subunit A in Holotrichia parallela

Proteomic analysis of Cry2Aa-binding proteins and their receptor function in Spodoptera exigua

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