Journal Article

Integrated Analysis of Polyphenol Oxidase Gene Expression and Enzymatic Activity in Purple-Fleshed Potatoes

Mestanza, Marilu, Rituay, Pablo, Condori-Apfata, Jorge Alberto, del Rio, Alfonso H., Hernández-Amasifuen, Angel David, Eriksson, Dennis, Guerrero-Abad, Juan Carlos

2026

Overview

Colored potato cultivars are rich in phenolic compounds that confer high antioxidant capacity; however, these beneficial metabolites could be susceptible to oxidation by polyphenol oxidases (PPOs), leading to enzymatic browning and the loss of antioxidant potential. Despite the agronomic relevance of this trade-off, the dynamics of the PPO gene family (StPPOs) gene expression in pigmented potatoes remains poorly characterized. Here, we present an integrated biochemical and molecular analysis of two purple-fleshed Peruvian landraces (Siriñacha and Angashungo), a partially pigmented landrace (Sapa), and non-pigmented cultivars, including the commercial cultivar Desirée. We quantified the total phenolic content, antioxidant capacity, and enzymatic browning index (EBI) using colorimetric and spectrophotometric methods. We also generated gene expression profiles of ten StPPO genes using semi-quantitative and digital PCR. Purple-fleshed cultivars exhibited significantly higher phenolic content and antioxidant capacity but also displayed accelerated browning kinetics compared to non- or partially pigmented genotypes. Expression analysis revealed cultivar-specific StPPO patterns, with StPPO2 and StPPO8 being markedly upregulated in pigmented materials, particularly StPPO8. These findings provide the first integrated biochemical and transcriptional evidence linking specific StPPO isoforms to enzymatic browning in colored potatoes, and highlight their potential for biotechnological applications.

• Publisher: MDPI AG,Multidisciplinary Digital Publishing Institute (MDPI)
• Subject: Agricultural and Veterinary Sciences / Agricultural Biotechnology / Analytical chemistry / Antioxidants / Biotechnology / Bioteknologi med applikationer på växter och djur / Browning / Colorimetry / Cultivars / Enzymatic activity / enzymatic browning / Enzymes / Enzymic browning / Gene expression / Genes / Genetic research / Genetics and Breeding in Agricultural Sciences / Genetik och förädling inom lantbruksvetenskap / Genotypes / Isoforms / Lantbruksvetenskap och veterinärmedicin / Metabolism / Metabolites / Oxidases / Oxidation / Phenolic compounds / Phenols / Physiology / Polyphenol oxidase / polyphenol oxidases (PPO) / Potatoes / purple potato cultivars / Spectrophotometry