Distribution and diversity of Dipteran-specific cry and cyt genes in native Bacillus thuringiensis strains obtained from different ecosystems of Iran

Abstract

One hundred and twenty-eight Bacillus thuringiensis isolates from fields of different ecological regions of Iran were collected to study the distribution and diversity of Dipteran-specific cry and cyt genes. The percentage of samples with Bt showed significant differences between different regions and also between different fields. The most Bt frequency was observed in the soil samples collected from Caspianic zone (7%) and soils of cotton (17%). Characterization of isolates was based on morphological characteristics of crystals, plasmid profiles and protein band patterns as well as PCR analysis using general and specific primers for 22 different cry and cyt genes encoding proteins active against mosquitoes. Thirty-eight different cry gene profiles were detected in this collection. Several of them were found to be different from all previously published profiles and none of the previous researches reported these numbers of profiles. Strains containing cry2-type genes were the most abundant and represent 57.1% of the isolates. Strains harboring cry24 and cry10 genes were also highly abundant (38.7 and 32.8%, respectively). cry11, cry4, cry17, cry19, cry21, cry29, cyt1, and cry9 genes were less abundant, found in 25.7, 14.3, 11.4, 1.4, 4.3, 1.4, and 10% of the strains, respectively. Among the cry2 gene containing isolates, 37.5% strains harbored cry2Aa, 55% cry2Ab, 2.5% cry2Ac, and 5% other or novel cry2-type genes. Among the cry4 gene containing isolates, 0% strains harbored cry4A, 60% cry4B, and 40% cry4C, cry4D or novel cry4 type genes. Finally, based on crystal morphology, protein patterns and PCR, 21 strains were selected as potentially high Dipteran-active for bioassays. Also our results showed that some of the isolates may harbor minimum a putative novel cry gene.

Coleopteran-specific and putative novel cry genes in Iranian native Bacillus thuringiensis collection

“…Cry proteins are very selectively active against certain insect species, so the strains containing several types of cry genes encoding highly active insecticidal crystal proteins might be predicted to have a wider pest spectrum or increased activity. This would lead to additional broad spectrum and highly toxic B. thuringiensis insecticides (Salehi Jouzani et al, 2008a). This study was the first research in which B. thuringiensis isolates were screened almost for all coleopteran-active cry genes (19 cry genes).…”

Isolation and characterization of native Bacillus thuringiensis strains from Saudi Arabia with enhanced larvicidal toxicity against the mosquito vector Anopheles gambiae (s.l.)

“…Here, Bt 63 contained the cry4Ba , cry10 , cry11A , cyt1Aa and cyt2Aa genes, but lacked cry4A . In Iran, Jouzani et al [32] isolated 128 Bt strains from different ecological regions of Iran with dipteran-specific toxicity and detected cry4B in 60% of isolates and cry4C or cry4D in 40% of isolates, whereas cry4A was not detected in any strains.…”

Abundance and diversity of Bacillus thuringiensis in Bangladesh and their cry genes profile

“…Both expected and spurious bands were observed and the Bt strains with desired amplicons of about 277, 639, 525, 459, 376, 492, and 348 bp for cry1, cry2, cry3, cry4A, cry8, cry9, and cry10 genes respectively were considered as positive. Spurious products are actually generated if mismatch in priming occurs which enhances the getting of putative novel cry genes as reported in many studies (Jouzani et al, 2008;Bozlagan et al, 2010).…”