Step-by-step explanation:
There are two possible transgenes that could be used to create a non-ripening banana that requires ethylene to initiate the ripening process:
Gene for ethylene receptor: One possible transgene would be the gene for the ethylene receptor. By inserting this gene into the banana, the receptor would not respond to naturally occurring ethylene in the fruit, preventing the ripening process. When exogenous ethylene is applied, it would then activate the receptor and trigger the ripening process.
Gene for ethylene synthesis: Another possible transgene would be the gene for the enzyme responsible for ethylene synthesis. By inserting this gene into the banana, the fruit would not produce its own ethylene and therefore would not initiate the ripening process. When exogenous ethylene is applied, it would then initiate the ripening process.
Of these two transgenes, the gene for the ethylene receptor may have a better chance of success because it is more specific to the ripening process. This means that the receptor would only respond to ethylene and not to other factors that could trigger ripening, such as changes in temperature or humidity. In contrast, the gene for ethylene synthesis could potentially affect other processes in the fruit that rely on ethylene, such as growth and development.
Additionally, there is evidence to suggest that transgenic bananas with the gene for the ethylene receptor have been successfully created and tested in laboratory settings. These bananas have been shown to remain firm and unripe even after being stored for several weeks, and can be induced to ripen by application of exogenous ethylene. Therefore, the gene for the ethylene receptor may have a better chance of success in creating a transgenic banana that does not ripen until exogenous ethylene is applied.