  New recent results in supersymmetric gauge theories based on holomorphy and
symmetry considerations are extended to the case where the gauge coupling
constant is given by the real part of a chiral superfield. We assume here that
its dynamics can be described by an effective quantum field theory. Then its
vacuum expectation value is a function of the other coupling constants, viewed
as chiral background superfields. This functional dependence can be determined
exactly and satisfies highly non-trivial consistency checks.
