title: [Advances in effects of insecticidal crystal proteins released from transgenic Bt crops on soil ecology].
abstract: With the large scale cultivation of transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal crystal proteins in the world, the problem of environmental safety caused by these Bt crops has received extensive attention. These insecticidal crystal proteins can be released into the soil continuously in the growing period of Bt plants. If their accumulation of the insecticidal crystal proteins exceeds consumption by insect larvae and degradation by the environmental factors, these insecticidal crystal proteins could constitute a hazard to non-target insects and soil microbiota. There are three main ways to release insecticidal crystal proteins into soil for Bt plants: root exudates, pollen falling, and crop reside returning. The Bt insecticidal crystal proteins released into soil can be adsorbed rapidly by active soil particles and the absorption equilibrium attained within 1-3 h. The adsorption protects Bt insecticidal crystal proteins against soil microbial degradation or enzyme degradation, which leads to remarkable prolong of the persistence of insecticidal activity. The change of soil microorganism species is an important index for evaluating the effect of Bt plants on soil ecology. The research showed that these insecticidal crystal proteins released by the Bt plant root exudates or Bt organism had no toxicity to the soil earthworms, nematodes, protozoa, bacteria and fungi; however, it could reduce the mycelium length of the arbuscular mycorrhizal fungi (AMF) and restrain AMF to form invasion unit. The influencing degree of Bt protein on soil enzyme activity varied with the releasing modes or growth period of Bt crops. Bt Cry1Ab protein can be taken up from soil by parts of following crops; however, different results were obtained with different commercial kits. To better understand the soil ecological evaluation about the insecticidal crystal proteins released from transgenic Bt crops, this review provides a comprehensive overview about the release, adsorption and residue of Bt insecticidal crystal proteins in soil, as well as their effects on soil protozoa, soil microorganism, soil enzyme activity and following crops.
authors.affiliation: Department of Food Science, Tianjin Agricultural University, Tianjin 300384, China. zhouxueyongts@163.com
authors.forename: Xue-Yong
authors.initials: XY
authors.lastname: Zhou
authors.forename: Ning
authors.initials: N
authors.lastname: Liu
authors.forename: Man
authors.initials: M
authors.lastname: Zhao
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Lang
authors.initials: L
authors.lastname: Zhou
authors.forename: Zong-Wen
authors.initials: ZW
authors.lastname: Tang
authors.forename: Fei
authors.initials: F
authors.lastname: Cao
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000009:adverse effects* / Q000235:genetics*; D018556:Crops, Agricultural / Q000235:genetics*; D017753:Ecosystem; D004731:Endotoxins / Q000009:adverse effects* / Q000235:genetics*; D006460:Hemolysin Proteins / Q000009:adverse effects* / Q000235:genetics*; D009835:Oligochaeta / Q000187:drug effects; D030821:Plants, Genetically Modified / Q000235:genetics*; D012988:Soil Microbiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis