How to deal with transactions in domain layer

I have a question about handling transactions between data and domain layer.
Think about a usecase where two entities should be persisted into a local database in one transaction.
Should the domain layer know something about "transactions" when calling into the data layer and what about "nested transaction"? Who is responsible to decide whether two or more operations should handled atomic as the domain layer doesn't know something about where and how the data is persisted.
Another point is also how to handle if there is a foreign key relationship between entities.

Thank you for any advice.