Major fungal postharvest diseases of papaya: Current and prospective diagnosis methods

Papaya (Carica papaya) had become an important crop in Malaysia due to its health benefits and economic development such as food processing. However, it suffered a serious postharvest loss via poor handling during the postharvest chain, which promotes the growth and development of pathogens epiphytically and endophytically. Most postharvest diseases are fungal, and they can lead to irreversible changes in the fruit quality in papaya-producing countries including Malaysia. To reduce postharvest losses, early diagnosis and identification are recommended to detect the spread of the diseases while constructing effective postharvest management against them. Traditional diagnosis techniques are commonly used to detect causal agents by relying on visible observations as well as biochemical analysis. More advanced technologies are introduced using molecular and immunological approaches which provide sensitive and accurate identification of postharvest diseases. However, due to their pricing and effectiveness, biosensors are optimal for replacing the limitations of these conventional techniques for effective and user-friendly disease diagnosis on-field. Subsequently, postharvest control of papaya fruit could be opted to delay the disease establishment by understanding the pathogen's identity. This review assesses critically the progress that has been made in postharvest disease diagnosis in papaya. Prospective methods of diagnosis are also elaborated.