ACS-ZMØØ1-9 - InVigor™ maize | BCH-LMO-SCBD-14765 | Living Modified Organism | Biosafety Clearing-House

Living Modified Organism (LMO)
Decisions on the LMO Risk Assessments  
published: 05 Jun 2006 last updated: 16 Jul 2013
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.
InVigor™ maize
The maize line MS3 was genetically engineered to exhibit male sterility, by inserting the barnase ribonuclease gene under the tapetum specific promoter TA29 which results in the destruction of the tapetum and the plant being unable to produce viable pollen.

Tolerance to glufosinate ammonium, the active ingredient in phosphinothricin-based herbicides, was conferred by introducing the bar gene encoding the enzyme phosphinothricin-N-acetyltransferase (PAT).
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.
Corn line: H99
  • ACS-ZMØØ5-4 - InVigor™ maize
    | Bayer CropScience | Changes in physiology and/or production (Reproduction, Male sterility), Resistance to antibiotics (Ampicillin), Resistance to herbicides (Glufosinate)
Characteristics of the modification process
pVE108 and pMc5barstar
  • Electroporation
Some of these genetic elements may be present as fragments or truncated forms. Please see notes below, where applicable.
DNA insert from pVE108 vector
Vector contains the coding sequence for the barnase gene and the bialaphos resistance (bar) gene. the expression cassettes were in a sense, antisense orientation.

DNA insert from  pMc5barstar vector
Vector was co-transformed with the pVE108 vector as a helper vector containing the barstar gene which binds to and inhibits the barnase protein. This is to ensure the barstar ribonuclease does not affect the bacterial host during the development stage.

Molecular analyses of the transformed plant show that the transferred elements are integrated at one site in the corn genome and are inherited as a single locus. The inserted DNA resides on 2 adjacent fragments. One ~12 kb fragment consisting of a head-to-tail dimer of pVE108 and a ~9kb fragment consisting of one pVE108 copy and a rearranged piece of pMc5barstar. Thus the insert of the MS3 contains a part of pMc5barstar plasmid. There is no clear indication about the completeness of pVE108 copies.
LMO characteristics
  • Food
  • Feed
  • Biofuel
Detection method(s)
Additional Information
Glufosinate chemically resembles the amino acid glutamate and acts to inhibit an enzyme, called glutamine synthetase, which is involved in the synthesis of glutamine. Essentially, glufosinate acts enough like glutamate, the molecule used by glutamine synthetase to make glutamine, that it blocks the enzyme's usual activity. Glutamine synthetase is also involved in ammonia detoxification. The presence of glufosinate results in reduced glutamine levels and a parallel increase in concentrations of ammonia in plant tissues. This leads to cell membrane disruption and cessation of photosynthesis resulting in plant withering and death.

Glufosinate tolerance in this maize line is the result of introducing the bar gene encoding the enzyme phosphinothricin-N-acetyltransferase (PAT) isolated from the common aerobic soil actinomycete, Streptomyces hygroscopicus. The PAT enzyme catalyzes the acetylation of phosphinothricin, detoxifying it into an inactive compound. The PAT enzyme is not known to have any toxic properties.

The male-sterile trait was introduced by inserting the barnase gene, isolated from Bacillus amyloliquefaciens, a common soil bacterium that is frequently used as a source for industrial enzymes. The barnase gene encodes for a ribonuclease enzyme (RNAse) that is expressed only in the tapetum cells of the pollen sac during anther development. The RNAse affects RNA production, disrupting normal cell functioning and arresting early anther development, thus leading to male sterility.

The introduced DNA also included the barstar gene from B. amyloliquefaciens that encodes a specific inhibitor of the barnase RNAse. The barstar gene was included to prevent the RNAse from disrupting the development of bacteria in which the introduced DNA was prepared.

Two antibiotic resistant genes were also introduced into this LMO: the beta-lactamase gene (bla) and chloramphenicol acetyl transferase (cat) genes, encoding resistance to the antibiotics ampicillin and chloramphenicol, respectively. These were included as selectable marker genes to identify bacteria transformed with recombinant plasmids. The expression of these three genes (barstar, bla, and cat) was regulated by bacterial promoters that are not active in plants.