When we create a feature that becomes work for a developer in JIRA, we assign the ticket to a primary/original developer. When the work is done the ticket is assigned for code review and then again for QA. What gets lost is who the primary/original developer was.
One solution would be to create a custom field called Original assignee, where you could populate this information. This custom field can also be sent over to JIRA so that teams across both tools can see all of the key information.
You can create a custom field of type=pre-defined choice list and include all users in the choice list.
Note that if more team members join the team, you'll need to update this list. In the future, we're likely to add the ability to show a User list on custom fields, but this is not live yet.
Hope that this can help your workflow.