  We prove (in superspace) the equivalence between the higher-derivative N=1
supergravity, defined by a holomorphic function F of the chiral scalar
curvature superfield, and the standard theory of a chiral scalar superfield
with a chiral superpotential W, coupled to the (minimal) Poincare supergravity
in four spacetime dimensions. The relation between the holomorphic functions F
and W is found. It can be used as the technical framework for the possible
scenario unifying the early Universe inflation and the present Universe
acceleration. We speculate on the possible origin of our model as the effective
supergravity generated by quantum superstrings, with a dilaton-axion field as
the leading field component of the chiral superfield.
