Disease resistance of ‘Zill’and ‘Keitt’mango fruit to anthracnose in relation to defence enzyme activities and the content of anti-fungal substances

Abstract

SummaryMango (Magnifera indica L.) is a popular fruit, but it is susceptible to post-harvest diseases. To study the resistance of mango fruit to anthracnose disease and the possible defence mechanisms involved, the resistance of two mango cultivars (‘Zill’ and ‘Keitt’) was examined in relation to their defence enzyme systems. The results showed that in both young or commercially mature fruit inoculated with Colletotrichum gloeosporioides, lesion sizes on ‘Keitt’ fruit were smaller than on ‘Zill’ fruit. For non-inoculated fruit harvested at commercial maturity, the disease index of ‘Keitt’ was lower than that of ‘Zill’. This indicates that ‘Keitt’ was more disease resistant than ‘Zill’. Compared with ‘Zill’, ‘Keitt’ fruit showed higher phenylalanine ammonia lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO) activities during development and storage, as well as elevated levels of H2O2, total phenolic compounds and lignin during development, and higher contents of H2O2 and lignin in harvested fruit early during storage. These results suggest that defence enzymes and compounds plays important roles in the resistance of mango fruit to anthracnose disease and could be used as indicators to screen for mango cultivars that are more resistant to post-harvest diseases.