Database Product Description
- Host Organism
- Solanum lycopersicum (Tomato)
- 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.
- Proposed Use
Production for human consumption.
- Product Developer
- Agritope Inc.
Summary of Regulatory Approvals
Summary of Introduced Genetic Elements Expand
Characteristics of Solanum lycopersicum (Tomato) Expand
DR tomato line 35 1 N was developed by using standard Agrobacterium binary vectors forintroducing into the genome of Large Red Cherry a S-adenosylmethionine hydrolase (SAMase) encoding gene derived from E. coli bacteriophage T3. This results in transformed cherry tomato plants that exhibit significantly reduced levels of S-adenosylmethionine (SAM), the substrate for conversion (through ACC synthase) to 1-aminocyclopropane-1-carboxylic acid (ACC) which is the first committed step in ethylene biosynthesis. Ethylene is an endogenous plant hormone known to play an important role in fruit ripening of climacteric fruits. Lack of a sufficient pool of SAM for conversion to ACC in fruit results in tomato fruit with significantly reduced ethylene biosynthetic capabilities and a modified ripening phenotype. In the case of line 35 1 N the phenotype is characterized by fruit in which ripening on the vine is delayed while ripening off the vine is essentially suspended. However, in either case, tomato fruits expressing SAMase ripen normally when exposed to exogenous ethylene.
The cherry tomato line for which Agritope is requesting this determination, line 35 1 N, contains a version of the sam-k gene modified in the 5' region of the gene with a Kozak consensus sequence. This construct encodes a functional SAMase protein. Since SAM plays a central role in numerous biosynthetic pathways in plants, expression of sam-k gene is under the control of an organ specific (fruit) and temporally regulated (post-climacteric) promoter. The efficacy of this strategy is demonstrated by the fact that the organ specific and temporal expression pattern of ethylene biosynthesis precisely matches the SAMase expression kinetics (ethylene synthesis is inversely correlated to SAMase expression) and provides an explanation of the observed modified ripening.
Links to Further Information Expand
This record was last modified on Tuesday, February 24, 2015