Involvement of enzymatic browning and peroxidase activity as resistance mechanisms in 'Golden Delicious' apples


Abstract:

In this study different experiments were carried out to determine if enzymatic browning is involved in the resistance of 'Golden Delicious' apples to Penicillium expansum, the causal agent of blue mould. For this purpose, and in order to have samples with different sensivity to this pathogen, fruits were picked at different maturity stages. Immediately after harvest, fruits were inoculated with a conidial suspension (104 conidia ml-1) of P. expansum and the percentage of altered fruits determined after 7 days of incubation at 20°C. Browning potential was determined in situ and the activity of the browning-related enzymes polyphenol oxidase (PPO) and peroxidase (POX) determined for each maturity stage, with or without ascorbate and their specific substrates. For each maturity stage a clear correlation was found between browning potential and disease resistance. In this relationship, PPO and POX activity were not limiting, but substrate availability was clearly determining. When incubated with ascorbate or 4-methylpyrocatechol a clear increase in sensitivity to the pathogen was observed. In contrast, pre-incubation with guaiacol led to increased resistance, especially in the less mature fruits. Collectively these results provide evidence that PPO and POX act synergistically and they may be considered as important factors in apples defence mechanisms.

Año de publicación:

2005

Keywords:

  • Penicillium expansum
  • polyphenol oxidase
  • Enzymatic browning
  • Peroxidase

Fuente:

scopusscopus

Tipo de documento:

Conference Object

Estado:

Acceso restringido

Áreas de conocimiento:

  • Fitopatología
  • Bioquímica
  • Bioquímica

Áreas temáticas:

  • Bioquímica