Cantaloupe A (delayed ripening) | BCH-LMO-SCBD-15388 | Living Modified Organism | Biosafety Clearing-House


Living Modified Organism (LMO)

Decisions on the LMO Risk Assessments  
last updated: 25 Jul 2012
Living Modified Organism identity
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Cantaloupe A (delayed ripening)
Cantaloupe A
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-15001-5 Neomycin Phosphotransferase II | Escherichia coli (ECOLX)
    Protein coding sequence | Resistance to antibiotics (Kanamycin)
  • BCH-GENE-SCBD-15017-5 S-adenosylmethionine hydrolase gene | Bacteriophage T3 (Phage T3, T3)
    Protein coding sequence | Changes in physiology and/or production (Ripening)
Canteloupe with delayed ripening due to expression of the SAMase gene from Escherichia coli bacteriophage T3
LMO characteristics
Detection method(s)
Additional Information
The A and B lines of cantaloupe (Cucumis melo) were developed through a specific genetic modification to express a reduced accumulation of S-adenosylmethionine (SAM) and consequently the trait of delayed ripening. This was accomplished by the introduction of a bacteriophage encoded enzyme, S-adenosylmethionine hydrolase, capable of degrading and thus reducing SAM. The conversion of SAM to 1-aminocyclopropane-1-carboxylic acid (ACC) is the first step in ethylene biosynthesis and the lack of sufficient pools of SAM results in significantly reduced synthesis of this phytohormone, which is known to play a key role in fruit ripening.

These lines were created by Agrobacterium-mediated transformation in which the transfer-DNA (T-DNA) contained the S-adenosylmethionine hydrolase encoding SAMase gene from Escherichia coli bacteriophage T3. The constitutive expression of the SAMase gene was controlled by inclusion of regulatory DNA sequences from A. tumefaciens. In addition, the T-DNA contained sequences encoding the enzyme neomycin phosphotransferase II (NPTII) from the Tn5 transposon of Escherichia coli, strain K12, under the control of the nos promoter from A. tumefaciens. The expression of NPTII activity was used as a selectable trait to screen transformed plants for the presence of the SAMase gene.