Description:
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GE-PPO Lettuce lines were developed using genome editing (details about the method(s) used are confidential business information).
The intended phenotype of GE-PPO Lettuce lines is reduced activity of polyphenol oxidase proteins, enzymes responsible for browning of cut-surfaces during storage and distribution. Reduced levels of PPO enzymes and/or their activity lead to a non-browning phenotype and hence increased shelf live.
The lettuce genome contains at least 19 putative PPO genes. Described lines of GE-PPO Lettuce comprise a mutation in each of at least two different PPO genes. The exact genes targeted in this event remain unknown. The developers used an expression vector, ID123, for polycistronic expression of gRNAs to edit PPO genes in lettuce. Patent documents indicate that except for the PPO-O gene, all PPO-gRNAs were designed to target the metal-binding domain of each respective PPO gene.
The final GE-PPO Lettuce lines produced by gene editing and subsequent segregation are null segregants which were screened by PCR to be free of transgene sequences.
Source:
- USDA-APHIS letter of inquiry 20-168-35_air
- Patent WO2021080761A1
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Links regarding to this GMO:
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USDA APHIS https://www.aphis.usda.gov/biotechnology/downloads/reg_loi/18-243-01_a4_air_cbidel.pdf ,
Patent WO2021080761A1 https://patents.google.com/patent/WO2021080761A1/en
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Transformation / Modification technique:
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_unknown
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