GM Crop Database

A, B

Trait: Delayed ripening by introduction of a gene that results in degradation of a precursor of the plant hormone, ethylene.

Trait Introduction: Agrobacterium tumefaciens-mediated plant transformation.

Country	Food	Feed	Environment	Notes
United States	1999			View Determination of nonregulated status pending, per announcement in Federal Registry, October 26, 1999. Petition withdrawn November 15, 1999.

Summary of Introduced Genetic Elements Expand

Code	Name	Type	Promoter, other	Terminator	Copies	Form
sam-k	S-adenosylmethionine hydrolase	DR
nptII	neomycin phosphotransferase II	SM	nopaline synthase (nos) from A. tumefaciens			Native

Characteristics of Cucumis melo (Melon) Expand

Center of Origin	Reproduction	Toxins	Allergenicity
Muskmelon is native to Iran.	Melon flowers are typically pollinated by bees.	There are no known toxins in melon.	People with allergies to other plants, especially ragweed, can be allergic to melon.

Abstract Collapse: 1. Introduction
The A and B lines of cantaloupe (Cucumis melo L.) 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.
2. Development of the Modified Plant
The cantaloupe lines A and B were created by Agrobacterium-mediated transformation in which the transfer-DNA (T-DNA) contained the S-adenosylmethionine hydrolase encoding sam-k gene from Escherichia coli bacteriophage T3. The constitutive expression of the sam-k 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 sam-k gene.

Links to Further Information Expand

Animal and Plant Health Inspection Service, USDA

This record was last modified on Thursday, February 26, 2015