Control of enzymatic browning in potato (Solanum tuberosum L.) by sense and antisense RNA from tomato polyphenol oxidase

Polyphenol oxidase (PPO) activity of Russet Burbank potato was inhibited by sense and antisense PPO RNAs expressed from a tomato PPO cDNA under the co ntrol of the 35S promoter from the cauliflower mosaic virus. Transgenic Rus set Burbank potato plants from 37 different lines were grown in the field. PPO activity and the level of enzymatic browning were measured in the tuber s harvested from the field. Of the tubers from 28 transgenic lines that wer e sampled, tubers from 5 lines exhibited reduced browning. The level of PPO activity correlated with the reduction in enzymatic browning in these line s. These results indicate that expression of tomato PPO RNA in sense or ant isense orientation inhibits PPO activity and enzymatic browning in the majo r commercial potato cultivar. Expression of tomato PPO RNA in sense orienta tion led to the greatest decrease in PPO activity and enzymatic browning, p ossibly due to cosuppression. These results suggest that expression of clos ely related heterologous genes can be used to prevent enzymatic browning in a wide variety of food crops without the application of various food addit ives.