METHOD: Chemical Assay CONDITIONS: Green House - 21C METHOD NARR: Enzyme assays, Northern and Western Blotting, were performed to determine PPO protein and mRNA levels in hjt tubers. The goal of the analysis was to compare relatbr and hjr. RESULTS NARR: Enzymatic activity was not detected in any preparation of hjt, neither crude nor purified. AUTHOR EXPLANATION: Hjt does not exhibit enzymatic browning or blackspot because it does not have enzya suggests that tubers of hjt produce PPO mRNA and protein, but that the protein may be structurally altered or lacking a cofactor and therefore inactive.