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Appl. Environ. Microbiol., 12 1997, 4883-4890, Vol 63, No. 12
E Ben-Dov, A Zaritsky, E Dahan, Z Barak, R Sinai, R Manasherob, A Khamraev, E Troitskaya, A Dubitsky, N Berezina and Y Margalith
An extended multiplex PCR method was established to rapidly identify and
classify Bacillus thuringiensis strains containing cry (crystal protein)
genes toxic to species of Lepidoptera, Coleoptera, and Diptera. The
technique enriches current strategies and simplifies the initial stages of
large-scale screening of cry genes by pinpointing isolates that contain
specific genes or unique combinations of interest with potential
insecticidal activities, thus facilitating subsequent toxicity assays. Five
pairs of universal primers were designed to probe the highly conserved
sequences and classify most (34 of about 60) genes known in the following
groups: 20 cry1, 3 cry2, 4 cry3, 2 cry4, 2 cry7, and 3 cry8 genes. The DNA
of each positive strain was probed with a set of specific primers designed
for 20 of these genes and for cry11A. Twenty-two distinct cry-type profiles
were identified from 126 field- collected B. thuringiensis strains. Several
of them were found to be different from all published profiles. Some of the
field-collected strains, but none of the 16 standard strains, were positive
for cry2Ac. Three standard and 38 field-collected strains were positive by
universal primers but negative by specific primers for all five known genes
of cry7 and cry8. These field-collected strains seem to contain a new gene
or genes that seem promising for biological control of insects and
management of resistance.
Copyright © 1997, American Society for Microbiology
Extended screening by PCR for seven cry-group genes from field- collected strains of Bacillus thuringiensis
Department of Life Sciences, Ben-Gurion University of the Negev, Be'er- Sheva, Israel.
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