Larvicidal Cry proteins from Bacillus thuringiensis are released in root exudates of transgenic B. thuringiensis corn, potato, and rice but not of B. thuringiensis canola, cotton, and tobacco

Saxena, Deepak; Stewart, C. Neal; Altosaar, Illimar; Shu, Qingyao; Stotzky, G.

doi:10.1016/j.plaphy.2004.03.004

Cited by 105 publications

(62 citation statements)

References 32 publications

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“…The roots of the GM 3BT contain Cry proteins that may get into contact with rhizosphere bacteria. Although it is still debatable if Cry proteins are in fact exudated by the roots (Saxena et al, 2004;Miethling-Graff et al, 2010), its release during root growth by the sloughing off of living cells or from wounded cells is very likely (Faure et al, 2009) and thus exposure to bacteria on the root surface can be expected. Considering the small proportion of Cry proteins in the total protein contents of the root cells (maximum B3% (w/w); see Materials and methods) and the lack of direct toxic effects on soil bacteria in general (Icoz and Stotzky, 2008), shifts in the bacterial community structure triggered by 3BT are expected to be minor.…”

Section: Discussionmentioning

confidence: 99%

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

et al. 2012

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Ribosomal 16S rRNA gene pyrosequencing was used to explore whether the genetically modified (GM) Bt-maize hybrid MON 89034 × MON 88017, expressing three insecticidal recombinant Cry proteins of Bacillus thuringiensis, would alter the rhizosphere bacterial community. Fine roots of field cultivated Bt-maize and three conventional maize varieties were analyzed together with coarse roots of the Bt-maize. A total of 547 000 sequences were obtained. Library coverage was 100% at the phylum and 99.8% at the genus rank. Although cluster analyses based on relative abundances indicated no differences at higher taxonomic ranks, genera abundances pointed to variety specific differences. Genera-based clustering depended solely on the 49 most dominant genera while the remaining 461 rare genera followed a different selection. A total of 91 genera responded significantly to the different root environments. As a benefit of pyrosequencing, 79 responsive genera were identified that might have been overlooked with conventional cloning sequencing approaches owing to their rareness. There was no indication of bacterial alterations in the rhizosphere of the Bt-maize beyond differences found between conventional varieties. B. thuringiensis-like phylotypes were present at low abundance (0.1% of Bacteria) suggesting possible occurrence of natural Cry proteins in the rhizospheres. Although some genera indicated potential phytopathogenic bacteria in the rhizosphere, their abundances were not significantly different between conventional varieties and Bt-maize. With an unprecedented sensitivity this study indicates that the rhizosphere bacterial community of a GM maize did not respond abnormally to the presence of three insecticidal proteins in the root tissue.

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Section: Discussionmentioning

confidence: 99%

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

et al. 2012

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“…Root exudation of insecticidal CryIAb protein from transgenic maize was first reported by Saxena and coworkers (Saxena et al 1999;Saxena and Stotzky, 2000;Saxena et al 2002a;Saxena et al 2004). A major band of 66 kDa migrating in SDS-PAGE was reported in exudates from event BT11 but not from the near-isogenic non-Bt corn after 7 and 15 days in hydroponic culture (Saxena et al 1999).…”

Section: Discussionmentioning

confidence: 85%

Bt protein rhizosecreted from transgenic maize does not accumulate in soil

Margarit¹,

Reggiardo²,

Permingeat³

2008

Electron. J. Biotechnol.

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“…Comme toute plante cultivée, les cultures transgéniques pourront entrer en interaction avec les organismes du sol par différentes voies, via leur système racinaire ou par les résidus de culture relâchés en saison ou appliqués au sol après la récolte. Les protéines recombinantes, excrétées dans le sol par les exsudats racinaires des plantes en culture (Borisjuk et al 1999;Saxena et Stotzky 2001a;Saxena et al 1999Saxena et al , 2002Saxena et al , 2004) ou libérées des tissus de la plante en décomposition (Saxena et Stotzky 2001a;Saxena et al 2004), pourront s'adsorber aux particules argileuses du sol et montrer des effets éventuels sur les espèces rési-dantes, en fonction de leur spécificité d'action et de leur stabilité dans l'environnement édaphique.…”

Section: Impacts Directs Sur Les Organismes Du Solunclassified

Impact environnemental des cultures transgéniques

Michaud

2006

phyto

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La publication d’un article scientifique sur les effets néfastes d’un hybride de maïs transgénique exprimant une δ-endotoxine duBacillus thuringiensiscontre des larves du papillon monarque causait, il y a quelques années, une controverse sans précédent sur l’impact environnemental des caractères recombinants introduits au bagage génétique des cultures agricoles. Le présent article de synthèse, complémentaire à un article de ce même numéro abordant la migration des transgènes dans l’environnement (Michaud 2005), discute de l’impact des caractères recombinants encodés par les transgènes sur l’incidence et le développement des différents organismes vivants du milieu. L’impact des nouveaux caractères est d’abord considéré à l’échelle des écosystèmes, à la lumière des effets exercés par les pratiques agricoles courantes sur la diversité biologique au champ. L’impact de ces caractères est ensuite considéré en fonction des interactions spécifiques établies au champ ou en conditions de laboratoire entre la plante modifiée et une gamme d’espèces modèles incluant des ravageurs herbivores secondaires, des arthropodes prédateurs et différents organismes du sol.

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Larvicidal Cry proteins from Bacillus thuringiensis are released in root exudates of transgenic B. thuringiensis corn, potato, and rice but not of B. thuringiensis canola, cotton, and tobacco

Cited by 105 publications

References 32 publications

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

Bt protein rhizosecreted from transgenic maize does not accumulate in soil

Impact environnemental des cultures transgéniques

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