Binding of individual Bacillus thuringiensis Cry proteins to the olive moth Prays oleae (Lepidoptera: Yponomeutidae)

ABSTRACT We designed five degenerate primers for detection of novel cry genes from Bacillus thuringiensis strains. An efficient strategy was developed based on a two-step PCR approach with these primers in five pair combinations. In the first step, only one of the primer pairs is used in the PCR, which allows amplification of DNA fragments encoding protein regions that include consensus domains of representative proteins belonging to different Cry groups. A second PCR is performed by using the first-step amplification products as DNA templates and the set of five primer combinations. Cloning and sequencing of the last-step amplicons allow both the identification of known cry genes encoding Cry proteins covering a wide phylogenetic distance and the detection and characterization of cry-related sequences from novel B. thuringiensis isolates.

Download Full-text

Proteolysis, histopathological effects, and immunohistopathological localization of δ-endotoxins of Bacillus thuringiensis subsp. kurstaki in the midgut of lepidopteran olive tree pathogenic insect Prays oleae

Molecular Biotechnology ◽

10.1007/bf02686109 ◽

2007 ◽

Vol 35 (2) ◽

pp. 141-148 ◽

Cited By ~ 18

Author(s):

S. Rouis ◽

M. Chakroun ◽

I. Saadaoui ◽

S. Jaoua

Keyword(s):

Bacillus Thuringiensis ◽

Olive Tree ◽

Prays Oleae ◽

Bacillus Thuringiensis Subsp ◽

Histopathological Effects

Download Full-text

Characterization of cry Genes in a Mexican Bacillus thuringiensis Strain Collection

Applied and Environmental Microbiology ◽

10.1128/aem.64.12.4965-4972.1998 ◽

1998 ◽

Vol 64 (12) ◽

pp. 4965-4972 ◽

Cited By ~ 182

Author(s):

Alejandra Bravo ◽

Sergio Sarabia ◽

Lorena Lopez ◽

Hernesto Ontiveros ◽

Carolina Abarca ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Specific Primers ◽

Cry Proteins ◽

Pcr Product ◽

Strain Collection ◽

Lepidopteran Insects ◽

Ecological Patterns ◽

Biogeographical Regions ◽

Selection Of

ABSTRACT Mexico is located in a transition zone between the Nearctic and Neotropical biogeographical regions and contains a rich and unique biodiversity. A total of 496 Bacillus thuringiensis strains were isolated from 503 soil samples collected from the five macroregions of the country. The characterization of the strain collection provided useful information on the ecological patterns of distribution of B. thuringiensis and opportunities for the selection of strains to develop novel bioinsecticidal products. The analysis of the strains was based on multiplex PCR with novel general and specific primers that could detect the cry1,cry3, cry5, cry7, cry8,cry9, cry11, cry12,cry13, cry14, cry21, andcyt genes. The proteins belonging to the Cry1 and Cry9 groups are toxic for lepidopteran insects. The Cry3, Cry7, and Cry8 proteins are active against coleopteran insects. The Cry5, Cry12, Cry13, and Cry14 proteins are nematocidal. The Cry11, Cry21, and Cyt proteins are toxic for dipteran insects. Six pairs of general primers are used in this method. Strains for which unique PCR product profiles were obtained with the general primers were further characterized by additional PCRs with specific primers. Strains containingcry1 genes were the most abundant in our collection (49.5%). Thirty-three different cry1-type profiles were identified. B. thuringiensis strains harboringcry3 genes represented 21.5% of the strains, and 7.9% of the strains contained cry11 and cyt genes.cry7, cry8, and cry9 genes were found in 0.6, 2.4, and 2.6% of the strains, respectively. No strains carrying cry5, cry12, cry13,cry14, or cry21 genes were found. Finally, 14% of the strains did not give any PCR product and did not react with any polyclonal antisera. Our results indicate the presence of strains that may harbor potentially novel Cry proteins as well as strains with combinations of less frequently observed cry genes.

Download Full-text

Occurrence and Ear Damage of Helicoverpa zea on Transgenic Bacillus thuringiensis Maize in the Field in Texas, U.S. and Its Susceptibility to Vip3A Protein

Toxins ◽

10.3390/toxins11020102 ◽

2019 ◽

Vol 11 (2) ◽

pp. 102 ◽

Cited By ~ 25

Author(s):

Fei Yang ◽

José C. Santiago González ◽

Jayme Williams ◽

Donald C. Cook ◽

Ryan T. Gilreath ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Helicoverpa Zea ◽

Sustainable Use ◽

Leaf Tissue ◽

Corn Earworm ◽

Laboratory Population ◽

Bt Maize ◽

Cry Proteins ◽

Damage Area ◽

The U.S

The corn earworm, Helicoverpa zea (Boddie), is a major pest of Bacillus thuringiensis (Bt) maize and cotton in the U.S.. Reduced efficacy of Bt plants expressing Cry1 and Cry2 against H. zea has been reported in some areas of the U.S.. In this study, we evaluated the occurrence and ear damage of H. zea on transgenic Bt maize expressing Cry proteins or a combination of Vip3A and Cry proteins in the field in Texas in 2018. We found that the occurrence of H. zea larvae and the viable kernel damage area on the ear were not different between non-Bt maize and Bt maize expressing Cry1A.105+Cry2Ab2 and Cry1Ab+Cry1F proteins. A total of 67.5% of the pyramided Bt maize expressing Cry1Ab+Cry1F+Vip3A was damaged by 2nd–4th instar larvae of H. zea. Diet bioassays showed that the resistance ratio against Vip3Aa51 for H. zea obtained from Cry1Ab+Cry1F+Vip3A maize was 20.4 compared to a field population collected from Cry1F+Cry1A.105+Cry2Ab2 maize. Leaf tissue bioassays showed that 7-day survivorship on WideStrike3 (Cry1F+Cry1Ac+Vip3A) cotton leaves was significantly higher for the H. zea population collected from Cry1Ab+Cry1F+Vip3A maize than for a Bt-susceptible laboratory population. The results generated from this study suggest that H. zea has evolved practical resistance to Cry1 and Cry2 proteins. Therefore, it is crucial to ensure the sustainable use of the Vip3A technology in Bt maize and cotton.

Download Full-text

Trials using Bacillus thuringiensis to control the olive moth, Prays oleae in Greece in 1976

Zeitschrift für Angewandte Entomologie ◽

10.1111/j.1439-0418.1977.tb04307.x ◽

2009 ◽

Vol 84 (1-4) ◽

pp. 436-440 ◽

Cited By ~ 6

Author(s):

C. Yamvrias ◽

E. C. Young

Keyword(s):

Bacillus Thuringiensis ◽

Prays Oleae

Download Full-text

Rearrangement of N-Terminal α-Helices of Bacillus thuringiensis Cry1Ab Toxin Essential for Oligomer Assembly and Toxicity

Toxins ◽

10.3390/toxins12100647 ◽

2020 ◽

Vol 12 (10) ◽

pp. 647

Author(s):

Sabino Pacheco ◽

Jean Piere Jesus Quiliche ◽

Isabel Gómez ◽

Jorge Sánchez ◽

Mario Soberón ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Conformational Changes ◽

Membrane Integrity ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Membrane Vesicles ◽

Insect Midgut ◽

Cry Proteins ◽

Cry1ab Toxin ◽

Domain I

Cry proteins produced by Bacillus thuringiensis are pore-forming toxins that disrupt the membrane integrity of insect midgut cells. The structure of such pore is unknown, but it has been shown that domain I is responsible for oligomerization, membrane insertion and pore formation activity. Specifically, it was proposed that some N-terminal α-helices are lost, leading to conformational changes that trigger oligomerization. We designed a series of mutants to further analyze the molecular rearrangements at the N-terminal region of Cry1Ab toxin that lead to oligomer assembly. For this purpose, we introduced Cys residues at specific positions within α-helices of domain I for their specific labeling with extrinsic fluorophores to perform Föster resonance energy transfer analysis to fluorescent labeled Lys residues located in Domains II–III, or for disulfide bridges formation to restrict mobility of conformational changes. Our data support that helix α-1 of domain I is cleaved out and swings away from the toxin core upon binding with Manduca sexta brush border membrane vesicles. That movement of helix α-2b is also required for the conformational changes involved in oligomerization. These observations are consistent with a model proposing that helices α-2b and α-3 form an extended helix α-3 necessary for oligomer assembly of Cry toxins.

Download Full-text