  We consider minimal immersions in MxR. We study existence and uniqueness of
associate and conjugate isometric immersions to a given minimal surface. We use
the theory of univalent harmonic map between surfaces. Then we study the
geometry of associate minimal vertical graphs. We prove that an associate
surface of a vertical graph on a convex domain is a graph. In the classical
theory it is a theorem of R. Krust.
