PCR and bioassays screening of Bacillus thuringiensis isolates from rice-fields of Rio Grande do Sul, specific to lepidopterans and coleopterans

Pinto, Laura Massochin Nunes; Fiúza, Lidia Mariana

doi:10.1590/s1517-83822003000400003

Cited by 8 publications

(7 citation statements)

References 15 publications

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“…tems have been shown to provide significant regulation of pest populations Pinto and Fiuza, 2003 . The cry gene and protein profiling and toxicity mortality, LC 50 and LT 50 of Bt isolates were significantly varied within habitats Liang et al, 2011 .…”

Section: Figmentioning

confidence: 99%

“…These results led us to suggest the presence of diversity in Bt isolates of Mizoram Table 3 and Fig.4 . Cry proteins that could be of particular interest for this study are: cry 4 and cry 9 since they have been reported as effective against dipterans especially mosquitoes Ben-Dov et al, 1997;Pinto and Fiuza, 2003 and most abundant in jhum soils. The characterization for most of the Bt collections were based on bioassays against different insect larvae without identification of the cry genes present in the Bt strains Schnepf et al, 1998 .…”

Section: Growth Curve Studies and Determination Of Harvesting Timementioning

confidence: 99%

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Diversity and Toxicity of <i>Bacillus thuringiensis</i> from Shifting Cultivation (Jhum) Habitat

2016

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Bacillus thuringiensis (Bt) strains were isolated from jhum-agriculture, jhum-forest, aquatic and fallow soil samples from Mizoram by acetate selection method. Isolates were characterized for biochemical typing, cry gene and protein profiling, growth curve study and toxicity against Culex tritaeniorhynchus. Bt frequency was high in jhum-agriculture land (69.56%) whereas low in jhum-forest soils (31.57%). Bt was found to be abundant in jhum shifting cultivation soil with an index ranging between 0.010 and 0.015. Majority of the isolates from jhum soils produced oval and spherical crystals and showed eleven types of crystal proteins groups. PCR analysis revealed predominance of dipteran-active cry genes (cry4 and cry9). The variations in crystal morphology, cry genes and Cry protein (s) from the isolates of Bt revealed molecular diversity. Higher mortality, lower lethal dose, and lesser time to kill were observed in Bt isolates from jhum soils than aquatic and fallow habitats. Based on the toxicity test, SC1 and HP7 isolates containing cry 4 and cry 9 genes showed higher activity. Growth curve analysis showed significant variations among Bt isolates to reach the sporulating stage. Higher growth index and lower mean generation time were observed in SC1 and HP7 Bt isolates. Bt strains express different endotoxin genes and crystal proteins and their harvesting time also varied from strain to strain. Significant variation was found in Bt isolates from jhum habitats in relation to the cry gene composition, protein profiling and toxicity. Results from this study suggest that novel Bt entomopathogens may complement for regulating mosquito vectors.

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Section: Figmentioning

confidence: 99%

Section: Growth Curve Studies and Determination Of Harvesting Timementioning

confidence: 99%

Diversity and Toxicity of <i>Bacillus thuringiensis</i> from Shifting Cultivation (Jhum) Habitat

2016

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“…The cry1, cry2, and cry9 genes are commonly found in isolates of B. thuringiensis toxic to Lepidoptera (Bravo et al 1998, Pinto & Fiuza 2003, Escudero et al 2007. Although vip genes are very toxic to many Lepidoptera (Yu et al 1997, Bhalla et al 2005, Fang et al 2007, Seifinejad et al 2008, they were not detected.…”

Section: Resultsmentioning

confidence: 99%

Cry Proteins from Bacillus thuringiensis Active against Diamondback Moth and Fall Armyworm

et al. 2015

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Biopesticides based on Bacillus thuringiensis and genetically modified plants with genes from this bacterium have been used to control Plutella xylostella (L.) and Spodoptera frugiperda (J.E. Smith). However, the selection pressure imposed by these technologies may undermine the efficiency of this important alternative to synthetic insecticides. Toxins with different modes of action allow a satisfactory control of these insects. The purpose of this study was to characterize the protein and gene contents of 20 B. thuringiensis isolates from soil and insect samples collected in several areas of Northeast Brazil which are active against P. xylostella and S. frugiperda. Protein profiles were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Polymerase chain reaction assays were used to determine toxin genes present within bacterial isolates. The protein profile of the majority of the isolates produced bands of approximately 130 kDa, suggesting the presence of Cry1, Cry8 and Cry9 proteins. The gene content of the isolates of B. thuringiensis investigated showed different gene profiles. Isolates LIIT-4306 and LIIT-4311 were the most actives against both species, with LC50 of 0.03 and 0.02 × 10(8) spores mL(-1), respectively, for P. xylostella, and LC50 of 0.001 × 10(8) spores mL(-1) for S. frugiperda. These isolates carried the cry1, cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry2, cry2A, cry8, and cry9C genes. The obtained gene profiles showed great potential for the control of P. xylostella and S. frugiperda, primarily because of the presence of several cry1A genes, which are found in isolates of B. thuringiensis active against these insects.

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“…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).…”

Section: Resultsmentioning

confidence: 99%

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

Pinto¹,

Dörr²,

Ribeiro³

et al. 2012

Braz. J. Microbiol.

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The screening of Bacillus thuringiensis (Bt) Cry proteins with high potential to control insect pests has been the goal of numerous research groups. In this study, we evaluated six monogenic Bt strains (Bt dendrolimus HD-37, Bt kurstaki HD-1, Bt kurstaki HD-73, Bt thuringiensis 4412, Bt kurstaki NRD-12 and Bt entomocidus 60.5, which codify the cry1Aa, cry1Ab, cry1Ac, cry1Ba, cry1C, cry2A genes respectively) as potential insecticides for the most important insect pests of irrigated rice: Spodoptera frugiperda, Diatraea saccharalis, Oryzophagus oryzae, Oebalus poecilus and Tibraca limbativentris. We also analyzed their compatibility with chemical insecticides (thiamethoxam, labdacyhalothrin, malathion and fipronil), which are extensively used in rice crops. The bioassay results showed that Bt thuringiensis 4412 and Bt entomocidus 60.5 were the most toxic for the lepidopterans, with a 93% and 82% mortality rate for S. frugiperda and D. saccharalis, respectively. For O. oryzae, the Bt kurstaki NRD-12 (64%) and Bt dendrolimus HD-37 (62%) strains were the most toxic. The Bt dendrolimus HD-37 strain also caused high mortality (82%) to O. poecilus, however the strains assessed to T. limbativentris caused a maximum rate of 5%. The assays for the Bt strains interaction with insecticides revealed the compatibility of the six strains with the four insecticides tested. The results from this study showed the high potential of cry1Aa and cry1Ba genes for genetic engineering of rice plants or the strains to biopesticide formulations.

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PCR and bioassays screening of Bacillus thuringiensis isolates from rice-fields of Rio Grande do Sul, specific to lepidopterans and coleopterans

Cited by 8 publications

References 15 publications

Diversity and Toxicity of <i>Bacillus thuringiensis</i> from Shifting Cultivation (Jhum) Habitat

Diversity and Toxicity of <i>Bacillus thuringiensis</i> from Shifting Cultivation (Jhum) Habitat

Cry Proteins from Bacillus thuringiensis Active against Diamondback Moth and Fall Armyworm

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

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