DAS-Ø6275-8 - Herbicide-tolerant, insect-resistant maize | BCH-LMO-SCBD-15187 | Living Modified Organism | Biosafety Clearing-House


Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
published: 21 Jun 2006 last updated: 09 Apr 2013
Living Modified Organism identity
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Herbicide-tolerant, insect-resistant maize
Insect-resistant and glufosinate ammonium herbicide tolerant maize produced by inserting the cry1F gene from Bacillus thuringiensis var. aizawai which confers resistance against certain lepidopteran pests, such as the European corn borer (Ostrinia nubilalis) and Sesamia spp, and the phosphinothricin N-acetyltransferase encoding gene (PAT) bar gene from Streptomyces hygroscopicus which confers tolerance to application of glufosinate-ammonium herbicide.
The term “Recipient organism” refers to an organism (either already modified or non-modified) that was subjected to genetic modification, whereas “Parental organisms” refers to those that were involved in cross breeding or cell fusion.
Characteristics of the modification process
  • Agrobacterium-mediated DNA transfer
Some of these genetic elements may be present as fragments or truncated forms. Please see notes below, where applicable.
  • BCH-GENE-SCBD-14987-8 Cry1F | Bacillus thuringiensis (Bt, Bacillus, BACTU)
    Protein coding sequence | Resistance to diseases and pests (Insects, Lepidoptera (butterflies and moths))
  • BCH-GENE-SCBD-14972-12 Phosphinothricin N-acetyltransferase gene | Streptomyces hygroscopicus (STRHY)
    Protein coding sequence | Resistance to herbicides (Glufosinate)
  • BCH-GENE-SCBD-100362-7 Ubiquitin gene promoter | Zea mays (Maize, Corn, MAIZE)
  • BCH-GENE-SCBD-100367-4 Proteinase inhibitor II gene terminator | Solanum tuberosum (Potato, SOLTU)
  • BCH-GENE-SCBD-100287-7 CaMV 35S promoter | Cauliflower mosaic virus (CaMV)
  • BCH-GENE-SCBD-104337-2 Alcohol Dehydrogenase 1, intron 1 | Zea mays (Maize, Corn, MAIZE)
Ubiquitin gene promoter includes the promoter region, first intron and 5' UTR.

The CaMV 35s promoter includes an additional copy of the upstream enhancer region of the promoter at the 5' end of the promoter.

Cry1F truncated coding sequence was modified for plant optimised expression but has an identical amino acid sequence as the first 1-605 of the native Cry1F protein except for a single amino acid residue substitution F604L.

Southern blot analysis indicated that a single truncated copy of the transformation cassette was integrated into the host genome. a truncation of the ubiquitin promoter and intron were shown. Analysis also indicated that there was no integration of segments of the vector backbone.
LMO characteristics
  • Food
  • Feed
Detection method(s)
Additional Information
The transgenic maize line TC6275 was genetically engineered to resist European Corn Borer (ECB), Southwestern corn borer (SWCB), fall armyworm (FAW), and black cutworm (BCW), and to a limited extent, corn earworm (CEW), by producing its own insecticide. TC6275 was also developed to express tolerance to the herbicide glufosinate ammonium. Two novel genes, a truncated cry1F gene and the bar gene were introduced into the maize hybrid line Hi-II using Agrobacterium-mediated transformation.

The cry1F gene, isolated from the common soil bacterium Bacillus thuringiensis var. aizawai, produces the insect control protein Cry1F, a delta-endotoxin. Cry proteins, of which Cry1F is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1F is lethal only when eaten by the larvae of lepidopteran insects (moths and butterflies), and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for the delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.

TC6275 maize also was developed to allow for the use of glufosinate ammonium as a weed control option, and as a breeding tool for selecting plants containing the cry1F gene. The herbicidal mode of action of glufosinate ammonium is related to the activity of glutamine synthetase (GS), the enzyme required for the synthesis of the amino acid glutamine. L-phosphinothricin, the active ingredient of glufosinate ammonium, is a structural analog of glutamate, and acts as a competitive inhibitor. After application of the herbicide, L-phosphinothricin competes with glutamine for its active sites on GS. The results of the inhibition of GS are an accumulation of ammonia in the plant, a reduction in the synthesis of glutamine, and an inhibition of photosynthesis. This causes the death of plant cells, and eventually, the entire plant. TC6275 maize contains the bar gene, which codes for the production of the enzyme phosphinothricin acetyl-transferase (PAT). This enzyme acetylates L-phosphinothricin rendering it inactive in the plant. The PAT enzyme is not known to have any toxic properties. The bar gene was isolated from the soil bacterium Streptomyces hygroscopius, the same organism from which L-phosphinothricin was originally isolated.