title: 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.
abstract: Larvicidal proteins encoded by cry genes from Bacillus thuringiensis were released in root exudates from transgenic B. thuringiensis corn, rice, and potato but not from B. thuringiensis canola, cotton, and tobacco. Nonsterile soil and sterile hydroponic solution in which B. thuringiensis corn, rice, or potato had been grown were immunologically positive for the presence of the Cry proteins; from B. thuringiensis corn and rice, the soil and solution were toxic to the larva of the tobacco hornworm (Manduca sexta), and from potato, to the larva of the Colorado potato beetle (Leptinotarsa decemlineata), representative lepidoptera and coleoptera, respectively. No toxin was detected immunologically or by larvicidal assay in soil or hydroponic solution in which B. thuringiensis canola, cotton, or tobacco, as well as all near-isogenic non-B. thuringiensis plant counterparts or no plants, had been grown. All plant species had the cauliflower mosaic virus (CaMV) 35S promoter, except rice, which had the ubiquitin promoter from maize. The reasons for the differences between species in the exudation from roots of the toxins are not known. The released toxins persisted in soil as the result of their binding on surface-active particles (e.g. clay minerals, humic substances), which reduced their biodegradation. The release of the toxins in root exudates could enhance the control of target insect pests, constitute a hazard to nontarget organisms, and/or increase the selection of toxin-resistant target insects.
authors.affiliation: Laboratory of Microbial Ecology, Department of Biology, New York University, New York, NY 10003, USA.
authors.forename: Deepak
authors.initials: D
authors.lastname: Saxena
authors.forename: C Neal
authors.initials: CN
authors.lastname: Stewart
authors.forename: Illimar
authors.initials: I
authors.lastname: Altosaar
authors.forename: Qingyao
authors.initials: Q
authors.lastname: Shu
authors.forename: G
authors.initials: G
authors.lastname: Stotzky
mesh_terms: D001426:Bacterial Proteins; D001673:Biodegradation, Environmental; D001681:Biological Assay; D003368:Gossypium / Q000382:microbiology; D049452:Green Fluorescent Proteins; D019476:Insect Proteins / Q000737:chemistry* / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D012275:Oryza / Q000382:microbiology; D010572:Pest Control, Biological; D018517:Plant Roots / Q000382:microbiology*; D030821:Plants, Genetically Modified / Q000382:microbiology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D012987:Soil; D011198:Solanum tuberosum / Q000382:microbiology; D013501:Surface-Active Agents / Q000494:pharmacology; D014026:Nicotiana / Q000382:microbiology; D003313:Zea mays / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; C095416:Cry toxin receptors; D019476:Insect Proteins; D008164:Luminescent Proteins; D011956:Receptors, Cell Surface; D012987:Soil; D013501:Surface-Active Agents; D049452:Green Fluorescent Proteins