Enzyme Analysis of Polyphenol Oxidase and ORE9 Gene Mutation in Lactuca sativa in a Study to Improve Shelf-Life

Jeane Ferro
Mutations to three polyphenol oxidase (PPO) genes and the ORE9 gene were investigated in Desert Storm Iceberg and Romaine lettuce due to their suggested improvement to shelf life. Polyphenol oxidases cause browning in lettuce by oxidizing phenolic compounds, which form melanin through non-enzymatic reactions. Inhibition of PPO may lengthen shelf life by preventing melanin formation. ORE9 encodes a protein thought to label other proteins for degradation, some being inhibitors of leaf senescence. PPO, peroxidase (POD), and total phenolics (TP) assays were performed weekly for three weeks on six different lettuce mutants, each homozygous for a single base substitution mutation. The mutants showed significantly less leaf PPO activity during week one, but by week three higher activity occurred. When averaged, none of the mutations resulted in a significant difference in PPO activity, POD activity, or TP, which suggests that the enzymatic effects of these mutations may not alter shelf life.

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Psychology and Philosophy