Q: Can a supplemental material be attached to a non-open access paper?
I was advised by the journal editor that it is sufficient for the sequence list of gene primers to show on the supplemental material, and I followed that advise. My manuscript was accepted. I can choose to publish open access (OA) or non-OA. Should I choose OA in this case?
Firstly, congrats on your manuscript being accepted!
Coming to your query, it seems to be more about making a choice between publishing OA and non-OA rather than about being able to attach supplemental material to a non-OA paper.
In case it is still about being able to attach supplemental material to a non-OA paper, it would be best to check the journal’s guidelines and/or mail the editor. As the editor was able to rightly advise you on the sequence list, they should be able to aptly guide you in this case as well.
In case your query is about making a choice between publishing OA and non-OA, you would be in a better position to decide. OA is done, as the name suggests, to make your research more accessible to other researchers and the public. However, it typically involves you making the payment, in the form of article processing charges (APCs). Sometimes, your institute could bear the cost (partially or fully) for this. With non-OA, people who wish to read your paper need to make a payment (typically as a subscription fee) to be able to read your paper. You may learn more about publishing OA vs non-OA in this resource: What are the differences between open access and standard subscription-based publication?
Hope that helps. All the best for the publication!