Phenolic Content Pattern, Polyphenol Oxidase and Lipoxygenase Activity in Relation to Albinism, Fruit Malformation and Nubbins Production in Strawberry (Fragaria x ananassa Duch)

Abstract

Total phenol content, polyphenol oxidase (PPO) and lipoxygenase (LOX) activity were determined in strawberry fruits to establish a relationship between phenolic content, PPO and LOX activity with the production of abnormal fruits in 10 different strawberry cultivars. The study revealed that all strawberry cultivars produced abnormal fruits in varying proportion. Highest percentage of abnormal fruits was produced by Etna (21.8%), and the lowest by Senga Sengana (3.7%). Among cultivars, Etna produced maximum percentage of albino (25.8%), malformed (22.7%) or nubbin (button) berries (16.9%), while the lowest percentage of albino (5.2%), and malformed fruits (2.5%) were produced by Senga Sengana, and nubbin (button) (2.9%) by Camarosa. Total phenol content and PPO and LOX activity varied widely among different strawberry cultivars. The highest phenol content was recorded in Senga Sengana (14.4 mg g−1, fresh tissue weight) and the minimum in Etna (3.1 mg g−1 fresh tissue weight). Likewise, Etna exhibited the minimum PPO activity (0.503 ΔA400 g−1 min−1) and Senga Sengana, the maximum (0.732 ΔA400 g−1 min−1). Similarly, normal fruits exhibited higher PPO activity (0.753 ΔA400 g−1 min−1) than abnormal fruits. The highest LOX activity was exhibited by Senga Sengana (0.462 μ katal kg−1) and the lowest by Etna (0.338 μ katal kg−1) Similarly, LOX activity was very high in normal fruits (0.568 μ katal kg−1) in comparison to abnormal ones. The regression equations developed between total phenol content, PPO and LOX activity with abnormal fruits revealed that an inverse relationship existed between total phenol content, PPO and LOX activity and production of abnormal fruits in strawberry.