Beta-amylase expression and starch degradation during banana ripening
Starch is the main form of carbon storage in bananas (Musa acuminata, cv. Nanicão) and Î²-amylase (EC 22.214.171.124) could contribute to starch mobilization during ripening by depolymerizing the Î±-glucan chains released by the endo-hydrolytic enzymes. This paper reports the cloning of a full-length Î²-amylase cDNA, along with the activity and expression profiles after treatment with ethylene or its antagonist 1-MCP. According to the results, banana Î²-amylase activity is highly correlated to a decrease in starch, being primary up-regulated by de novo synthesis. In fruit treated with 1-MCP the amount of Î²-amylase protein was almost undetectable, even though there was a strong induction of transcription, as a result of the recovering capability for autocatalytic production of ethylene.