Characterization of cry2-type genes of Bacillus thuringiensis strains from soil-isolated of Sichuan basin, China

Abstract

Sichuan basin, situated in the west of China, is the fourth biggest basin in China. In order to describe a systematic study of the cry2-type genes resources from Bacillus thuringiensis strains of Sichuan basin, a total of 791 Bacillus thuringiensis strains have been screened from 2650 soil samples in different ecological regions. The method of PCR-restriction fragment length polymorphism (PCR-RFLP) was used to identify the type of cry2 genes. The results showed that 322 Bacillus thuringiensis strains harbored cry2-type genes and four different RFLP patterns were found. The combination of cry2Aa/cry2Ab genes was the most frequent (90.4%), followed by cry2Aa (6.8%) and cry2Ab alone (2.5%), and only one novel type of cry2 gene was cloned from one isolate (JF19-2). The full-length of this novel gene was obtained by the method of thermal asymmetric interlaced PCR (Tail-PCR), which was designated as cry2Ag1 (GenBank No. ACH91610) by the Bt Pesticide Crystal Protein Nomenclature Committee. In addition, the result of scanning electron microscopic (SEM) observation showed that these strains had erose, spherical, bipyramidal, and square crystal. And the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that these strains harbored about one to three major proteins.These strains exhibited a wide range of insecticidal spectrum toxic to Aedes aegypti (Diptera) and Pieris rapae Linnaeus, 1758 (Lepidoptera). Particularly, JF19-2 contained cry2Ag gene had the highest insecticidal activity. All these researches mentioned above revealed the diversity and particularity of cry2-type gene resources from Bacillus thuringiensis strains in Sichuan basin.

Bioactivities of cry gene positive Bacillus thuringiensis (Berliner) (Bacillales: Bacillaceae) strains on Ephestia kuehniella Zeller, 1879 and Plodia interpunctella (Hübner, 1813) (Lepidoptera: Pyralidae)

“…Similar to our result, Sauka et al (2005) showed that among the native B. thuringiensis strains, 94.9% of them had cry2Aa/cry2Ab gene combination whereas 3.4% and 1.7% of them contained cry2Ab or cry2Aa, respectively. In addition, Liang et al (2011) reported that cry2Aa/cry2Ab gene combination was the most frequent (90.4%), whereas percentages of cry2Aa and cry2Ab positive genes in their B. thuringiensis strains were 6.8 and 2.5, respectively. In other words, occurrence of cry2Aa/cry2Ab gene combination was the most frequent compared to that of individual cry2-type genes in B. thuringiensis strains.…”

In silico identification of cross affinity towards Cry1Ac pesticidal protein with receptor enzyme in Bos taurus and sequence, structure analysis of crystal proteins for stability

“…Cry2Ab protein (ABC95996.1) showed maximum identity with pesticidal crystal protein Cry2Ab [ B.thuringiensis serovar kurstaki str ]. There has been an earlier report of Blastp analysis of Cry2 genes of B.thuringiensis isolated from soil [9]. …”

Bacillus thuringiensis monogenic strains: screening and interactions with insecticides used against rice pests

“…Until then, works with Cry2 protein against coleopterans had still not been reported. Although Cry1 proteins have originally been related in regards to their toxicity for lepidopterans, many studies have already reported their toxicity for coleopterans (10, 23, 25, 26, 30). These results evidence the toxic potential of Cry1 and Cry2 proteins against coleopterans, which until then was essentially associated to Cry3 and Cry9 proteins (11, 19).…”

“…Cry1 genes are most frequent in nature, representing over 43% of the reported cry genes. This class synthesizes proteins toxic mainly to the Lepidoptera order, while cry2 genes are toxic both to the Lepidoptera and Diptera orders (8, 23). Cross-order activity has been shown in 15 of the 87 pesticide crystal protein families, and most toxins were assessed for 10 species or less.…”