Determination and Distribution of cry -Type Genes of Bacillus thuringiensis Isolates from Taiwan

Abstract

Using PCR with a set of specific oligonucleotide primers to detect cryI-type genes, we were able to screen the cry-type genes of 225 BaciUlus thuringiensis soil isolates from Taiwan without much cost in time or labor. Some combinations of cry genes (the cry-type profile) in a single isolate were unique. We identified five distinct profiles of crystal genes from the B. thuringiensis soil isolates from Taiwan. The cry genes included cryL4(a), cryIA(b), crylA(c), cryIC, cryID, and cryIV. Interestingly, 501 B. thuringiensis isolates (93.5% of the total number that we identified) were isolated from areas at high altitudes. The profiles of cry-type genes were distinct in all isolation areas. The distribution of cry-type genes of our isolates therefore depended on geography. Using PCR footprinting to detect cryIC-type genes, we identified two distinct cryIC footprints from some of our isolates, indicating that these isolates may contain novel cryIC-type genes. B. thuringiensis isolates containing cryIA(a)-, cryL4(b)-, and cryL4(c)-type genes exhibited much greater activity against Plutella xylostella than did other isolates, indicating that multiple cry-type genes may be used as markers for the prediction of insecticidal activities.

Diversity of Colombian strains of Bacillus thuringiensis with insecticidal activity against dipteran and lepidopteran insects

“…However, some of the cry1 genes were not detected in this study (cry1Ad, cry1E, cry1F and cry9A). Accordingly, these genes were the most uncommon in some studies or totally absent in other (Chak et al 1994;Kim et al 1998;Kim 2000;Arango et al 2002;Maduell et al 2002;Uribe et al 2003;Martínez et al 2005). Although cry1C gene is commonly associated with cry1D gene, the present study showed 16 isolates with cry1D but not cry1C.…”

Contents of cry genes and insecticidal toxicity of Bacillus thuringiensis strains from terrestrial and aquatic habitats

“…In accordance with the present results, previous reports have also found that collections of strains from different environments may differ in their cry genes content. For example, Bravo et al (1998) found that the distribution of cry1A, cry1B, cry1C and cry1D was more frequent than cry1E and cry1F, and Chak et al (1994) reported that cry1A, cry1C and cry1D were more abundant in B. thuringiensis from Taiwan. The distribution of three genes, cry1C, cry1D and cry1E, was found to be statistically different in both collections, being more common within the terrestrial strains.…”

“…PCR analysis, bioassays and serological identification of B. thuringiensis collections demonstrated the large diversity that can be found among naturally-occurring strains (Ben-Dov et al 1997;Bravo et al 1998;Ferrandis et al 1999). Bacillus thuringiensis strains isolated from different habitats and geographical locations differ in the occurrence and diversity of cry genes content (Chak et al 1994;Bravo et al 1998). Moreover, the correlation of the cry genes profiles with toxicity has been reported to be at least partially dependent on the serovar (Porcar et al 2000).…”

Ecological distribution and characterization of four collections of Bacillus thuringiensis strains

“…With this technique, insecticidal activity of B. thuringiensis strains may be -at least to some extentpredicted, and novel cry genes may be identified. Screenings of cry genes have been performed among collections from several parts of the world including Spain [9,20], China [12,26], Mexico [5], Colombia [25], Taiwan [7], Bolivia [10], Israel, Kazakhstan, and Uzbekistan [4], among others.…”

“…Cerón et al[6] detected 19.5% of cry1 genes in a B. thuringiensis Mexican collection of 241 isolates. In a screening carried out in Taiwan, cry1 genes were found in 98.2% of the 225 isolates[7]. The occurrence of cry1 genes in a study of B. thuringiensis isolates from Israel, Kazakhstan, and Uzbekistan was 33.5 % among 72 isolates[4].…”