ACS-GHØØ1-3 - Liberty Link™ cotton | BCH-LMO-SCBD-14851 | Living Modified Organism | Biosafety Clearing-House


Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
published: 05 Jun 2006 last updated: 20 Jan 2023
Living Modified Organism identity
The image below identifies the LMO through its unique identifier, trade name and a link to this page of the BCH. Click on it to download a larger image on your computer. For help on how to use it go to the LMO quick-links page.
Liberty Link™ cotton
The cotton (Gossypium hirsutum) was modified for tolerance to glufosinate ammonium herbicides through the expression of Streptomyces hygroscopicus phosphinothricin N-acetyltransferase, which inactivate the herbicide through acetylation.
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.
Variety Coker 312
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-14972-12 Phosphinothricin N-acetyltransferase gene | Streptomyces hygroscopicus (STRHY)
    Protein coding sequence | Resistance to herbicides (Glufosinate)
  • BCH-GENE-SCBD-101416-6 Ti plasmid right border repeat | Agrobacterium tumefaciens (Agrobacterium)
    Plasmid vector
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    BCH-GENE-SCBD-100287-7 CaMV 35S promoter | Cauliflower mosaic virus (CaMV)
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    BCH-GENE-SCBD-100269-8 Nopaline Synthase Gene Terminator | Agrobacterium tumefaciens (Agrobacterium)
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    BCH-GENE-SCBD-101415-9 Ti plasmid left border repeat | Agrobacterium tumefaciens (Agrobacterium)
    Plasmid vector
The modified cotton contains a single gene cassette: Streptomyces hygroscopicus phosphinothricin N-acetyltransferase (bar). The bar coding sequence is under control of a Cauliflower mosaic virus 35S promoter and an Agrobacterium tumefaciens nopaline synthase terminator. Due to the constitutive nature of the viral promoter, high levels of transcription are expected from this gene cassette.

  • The initial two codons of the N-terminal of the bar coding sequence were synthetically modified to plant-preferred codons.
  • Southern blot analysis indicated that a single intact copy of the T-DNA was integrated into the cotton genome and no vector backbone sequences were present.
LMO characteristics
  • Feed
  • Fiber/textile
  • Food
Detection method(s)
Additional Information
The cotton line LLCotton25 was developed to allow the use of glufosinate ammonium (trade name Liberty®), as a weed control option in cotton production. 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. This modified cotton line LLCotton25 contains the bar gene, which codes for the production of the enzyme phosphinothricin acetyl-transferase (PAT). This enzyme acetylates glufosinate ammonium, rendering it inactive in the plant. The expression of the bar gene in LLCotton25 allows it to survive the otherwise lethal application of glufosinate ammonium. The bar gene was isolated from Streptomyces hygroscopius, a gram-positive soil bacterium.

LLCotton25 was developed by Agrobacterium-mediated transformation of the cotton variety ‘Coker312’ with a plasmid vector containing the bar gene. Whole plants were treated with glufosinate ammonium and successful transformants were detected by selecting plants that had not exhibited the phytotoxic effects of glufosinate ammonium