The Phylloplane as a Source of
            <i>Bacillus thuringiensis</i>
            Variants

Smith, Robert A.; Couche, Graham A.

doi:10.1128/aem.57.1.311-315.1991

Cited by 191 publications

(85 citation statements)

References 16 publications

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“…Furthermore, by sampling a large number of individual leaves from a relatively small geographical area we illustrated the lognormal distribution of the population and the effect of leaf type on average density and cry gene distribution. Aside from demonstrating the critical importance of spatial scale in sampling plans for bacterial populations on the phylloplane, this evidence adds further weight to the hypothesis first put forward in 1991 [4] and echoed more recently [5], that the relationship between B. thuringiensis, plants and herbivorous insects may show a degree of specificity. Further elucidation of potential ecological functions of populations of bacteria in natural habitats will depend on rigorous sampling plans and carefully chosen isolation procedures, but also on the estimation of growth of populations in such local habitats.…”

Section: Discussionsupporting

confidence: 54%

“…This means that our values are similar to those obtained by other authors. For example, Smith and Couche [4] isolated B. thuringiensis from between 50% and 70% of leaf samples analysed, whilst Ohba [3] found B. thuringiensis on 96% of mulberry trees examined, but only on 11% of leaves tested. The highest proportion of positive samples to date (74%) was attributed to the location of sampling sites in the tropics [8].…”

Section: Discussionmentioning

confidence: 99%

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Spatial variation in Bacillus thuringiensis/cereus populations within the phyllosphere of broad-leaved dock (Rumex obtusifolius) and surrounding habitats

Collier

Elliot

Ellis

2005

FEMS Microbiology Ecology

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The aim of this study was to determine the prevalence and toxin gene diversity of Bacillus thuringiensis/B. cereus in the phyllosphere of broad-leaved dock (Rumex obtusifolius) at a small spatial scale. B. thuringiensis/cereus populations were isolated from the phyllosphere of dock and neighbouring grass and in neighbouring soil using commercially available selective media which avoided the disadvantageous heat-shock selection procedure. The maximum density of B. thuringiensis/cereus in the dock phyllosphere was 1.9 x 10(4) CFU g(-1) but the between-leaf variation in numbers was found to follow a lognormal distribution. B. thuringiensis/cereus was also found at significant densities in soil and the phyllosphere of grass adjacent to the dock plants. PCR screening indicated that genes encoding cry1 toxin were present in the plasmids of 36.9% of B. thuringiensis/cereus isolates tested, 11.9% contained cry2, and none of the dock leaf isolates tested contained cry3, cry4, cry7 or cry8 genes. The diversity of cry genes is similar to that found from other studies focused on other parts of the world. This work is the first concerning the prevalence of B. thuringiensis/cereus on leaves in the UK, finding population sizes of previously unrecorded levels and a greater relative proportion of B. thuringiensis. We have also illustrated that before any ecological function can be investigated, suitable sampling scales need to be considered -- here we have shown that the minimum sampling unit should be individual leaves, to account for the log-normal distribution.

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Spatial variation in Bacillus thuringiensis/cereus populations within the phyllosphere of broad-leaved dock (Rumex obtusifolius) and surrounding habitats

Collier

Elliot

Ellis

2005

FEMS Microbiology Ecology

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“…In addition, over the years, Bt has been isolated from a variety of plant species (Collier et al, 2005;Jara et al, 2006;Vidal-Quist et al, 2009). Bt has been reported to be associated with plants during prolonged periods (Smith & Couche, 1991;Damgaard et al, 1997Damgaard et al, , 1998 or even after surface sterilisation of the plant samples (Mishra et al, 2009;Monnerat et al, 2009;Raymond et al, 2010;Melnick et al, 2011;de Goes et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Bacillus thuringiensiscolonises plant roots in a phylogeny-dependent manner

Vidal-Quist

Rogers

Mahenthiralingam

et al. 2013

FEMS Microbiol Ecol

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Although much is known about the pathology of Bacillus thuringiensis against invertebrates, current understanding of its natural ecology is limited. This study evaluated the biodiversity of B. thuringiensis in relation to its interaction with plants. Phylogenetic relationships between 44 reference and field-collected strains, determined using 16S rRNA and gyrB gene sequences, revealed a high degree of variability, similar to that found in databases. An Arabidopsis thaliana in vitro inoculation model was developed to screen the ability of B. thuringiensis to colonise roots. Significant colonisation differences up to 91-fold were observed between strains, and correlation between strain phylogeny and colonisation was found. The genetics and biochemistry of auxin production; presence of the gene encoding indole pyruvate decarboxylase; and the abilities of Bt strains to swarm, grow in rich/minimal media and affect root growth differed between the strains, but only auxin production correlated significantly with ability to colonise roots. Co-inoculation with Burkholderia phytofirmans PsJN or Pseudomonas fluorescens SBW25 produced no effect on B. thuringiensis colonisation levels, regardless of the co-inoculant. Similarly, root colonisation of A. thaliana mutants impaired in plant defences was not significantly higher compared with controls. This is the first systematic and phylogenetic evaluation of B. thuringiensis interaction with plants.

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“…The diversity of habitats from which subspecies of Bt strains have been isolated indicates that the ecology of this bacterium is probably very complex. For example, Bt has been isolated from habitats as different as soil, which is thought to be the preferred habitat (DeLucca et al 1981;Martin and Travers 1989;Chilcott and Wigley 1993), grain mills (DeLucca et al 1982), stored products (Kaelin et al 1994), rearing facilities (Dulmage 1970), the phylloplane (Smith and Couche 1991) and diseased insects (Feitelson et al 1992;Wiwat et al 2000). Recent studies on insecticidal crystal protein (ICP) genes are beginning to provide insight into the possible origin of the diversity of subspecies.…”

Section: Introductionmentioning

confidence: 99%

cry Genes profiling and the toxicity of isolates of Bacillus thuringiensis from soil samples against American bollworm, Helicoverpa armigera

Baig

Bukhari

Shakoori

2010

Journal of Applied Microbiology

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Aims: The aim of this study was to search for Bacillus thuringiensis (Bt) harbouring cry1A gene which could effectively control cotton pest, American bollworm, Helicoverpa armigera. Methods and Results: cry gene profiling of 50 Bt isolates showed the presence of cry1, cry2, cry3, cry4, cry7, cry8 and cry9 genes. None of the isolates harboured cry1 gene alone. It was always found in combination with cry3. There was no isolate positive for cry10 gene. Considering isolates with single cry genes, the frequency of cry4 was predominant (22%) followed cry2 (6%), cry3 (4%) and cry8 (2%). Isolates having two cry genes in combination had 14% incidence for cry2 + cry4, 12% for cry3 + cry4 and 10% for cry1 + cry3. The most dominant three gene linkage was cry1 + cry3 + cry4. Further profiling of cry1 gene showed that cry1K gene was abundantly present in all combinations such as cry1A, cry1D, cry1F and cry1I. However, cry1C existed independent of other subtypes. Finally, the Bt isolates with cry1A were analyzed for 16S rRNA gene, which showed two distinct groups of isolates on the basis of sequence homology. Bioassays of spore-crystal mixtures of 8, 17, 21 and 26 harbouring cry1 against neonate larvae of H. armigera showed LC 50 1288, 1202, 467AE7, 524AE8 and 108AE5 lg ml )1 . The SBS-Bt26 showed fourfold higher toxicity than the cry 1Ac harbouring positive control, HD-73. Conclusions: None of the isolates harboured single cry 1 gene. They were always in combination of two or three genes. A Bt isolate (Bt26) had fourfold higher toxicity against H. armigera larvae compared with the positive control HD 73 and hence can be commercially exploited to control insect pest. Significance and Impact of the Study: The inter relationship between the cry genes content and the toxicity may allow better understanding of Bt ecology.

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The Phylloplane as a Source of Bacillus thuringiensis Variants

Cited by 191 publications

References 16 publications

Spatial variation in Bacillus thuringiensis/cereus populations within the phyllosphere of broad-leaved dock (Rumex obtusifolius) and surrounding habitats

Spatial variation in Bacillus thuringiensis/cereus populations within the phyllosphere of broad-leaved dock (Rumex obtusifolius) and surrounding habitats

Bacillus thuringiensiscolonises plant roots in a phylogeny-dependent manner

cry Genes profiling and the toxicity of isolates of Bacillus thuringiensis from soil samples against American bollworm, Helicoverpa armigera

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