Does a non-self-signed certificate, imported into root store, require a (self-signed) issuer to also be imported into the root store?

Does a non-self-signed certificate, imported into root store, require a (self-signed) issuer to also be imported into the root store?

Suppose I've a certificate A that is signed by another certificate B. Is it then sufficient to only import A into the root store, i.e. certificate validation stops at A, or should B also be imported into the root store for proper certificate validation?

The reason I'm asking this question, is that I've encountered different results with different products (e.g. web browser or system), and so I want to know the right way.