The Correlation of the Presence and Expression Levels of cry Genes with the Insecticidal Activities against Plutella xylostella for Bacillus thuringiensis Strains

Abstract

The use of Bacillus thuringiensis (Bt) strains with high insecticidal activity is essential for the preparation of bioinsecticide. In this study, for 60 Bt strains isolated in Taiwan, their genotypes and the correlation of some cry genes as well as the expression levels of cry1 genes, with their insecticidal activities against Plutella xylostella, were investigated. Pulsed field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) results revealed that the genotypes of these Bt strains are highly diversified. Also, a considerable number of the Bt strains isolated in Taiwan were found to have high insecticidal activities. Since strains that showed individual combined patterns of PFGE and RAPD exhibited distinct insecticidal activities against P. xylostella, thus, these genotypes may be useful for the identification of the new Bt strains and those which have been used in bioinsecticides. In addition, although the presence of cry2Aa1 may have a greater effect on the insecticidal activity of Bt strains in bioassay than other cry genes, only high expression level of cry1 genes plays a key role to determine the insecticidal activity of Bt strains. In conclusion, both RAPD and PFGE are effective in the differentiation of Bt strains. The presence of cry2Aa1 and, especially, the expression level of cry1 genes are useful for the prediction of the insecticidal activities of Bt strains against P. xylostella.

Identification of Bacillus thuringiensis Strains for the Management of Lepidopteran Pests

“…Accordingly, differences in these features may also lead to variations in the susceptibility (Fortier et al 2007;Talaei-Hassanloui et al 2014;Jurat-Fuentes and Crickmore 2017;Kunthic et al 2017). In addition, the synergistic or antagonistic interactions between the Cry and Vip proteins, as well as the expression level of these proteins are factors that can influence the toxicity of Bt strains (Chen et al 2014;Lemes et al 2014).…”

Assessment of the Antimicrobial Activity and the Entomocidal Potential of Bacillus thuringiensis Isolates from Algeria

“…Cry2 proteins, some of which are active against both Lepidoptera and Diptera, form cuboidal crystals [ 24 , 77 , 78 , 79 ]. Therefore, the combination of several crystal shapes within an individual B. thuringiensis isolate, which is an indication of the presence of Cry proteins from different families, holds the potential for a spectrum of activity against a broad range of insect pests [ 30 , 31 ].…”

“…These receptors are absent in beneficial insects, plants, and mammals [ 26 , 29 ]. The identification of B. thuringiensis isolates carrying a wide variety of cry genes suggests a broad entomotoxic spectrum against different insect hosts [ 30 , 31 ].…”

Rhizobacteria strains as promoters of rooting in hybrids of Eucalyptus nitens × Eucalyptus globulus

“…The PCR product was sent to Macrogen (Seoul, South Korea) for its sequencing, and the sequences were edited with the software GENEIUS and inserted into the National Center for Biotechnology Information database (NCBI, US National Library of Medicine, Bethesda Maryland, USA) for the rhizobacterial strains identification. Afterwards, a complementary identification was developed in order to prove the identity of the strains in which were used the pair of specific cry8f and cry8r primers of Bacillus thuringiensis (Chen et al, 2014) in a new PCR. The PCR conditions were the same as those previously used with modification in the temperature program as follows: One cycle of 3 min at 94 °C; 35 cycles consisting of three segments; first segment 30 s at 94 °C, second segment 40 s at 55 °C, and third segment from 1 to 72 °C; then one cycle of 5 min at 72 °C maintaining the final PCR product at 4 °C.…”