  At the tree level, the maximally helicity violating amplitudes of N gauge
bosons in open superstring theory and of N gravitons in supergravity are known
to have simple representations in terms of tree graphs. For superstrings, the
graphs encode integral representations of certain generalized Gaussian
hypergeometric functions of kinematic invariants while for supergravity, they
represent specific kinematic expressions constructed from spinor-helicity
variables. We establish a superstring/supergravity correspondence for this
class of amplitudes, by constructing a mapping between the positions of gauge
boson vertices at the disk boundary and the helicity spinors associated to
gravitons. After replacing vertex positions by a larger set of N(N-3)/2
coordinates, the superstring amplitudes become (multiple) Mellin transforms of
supergravity amplitudes, from the projective space into the dual Mellin space
of N(N-3)/2 kinematic invariants. Similarly, inverse Mellin transforms
transmute open superstrings into supergravity. We elaborate on the properties
of multiple Mellin and inverse Mellin transforms in the framework of
superstring/supergravity correspondence.
