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We construct a family of viable scalar-tensor models of dark energy (DE)which possess a phase of late-time acceleration preceded by a standard matterera, while at the same time satisfying the local gravity constraints (LGC). Thecoupling Q between the scalar field and the non-relativistic matter in theEinstein frame is assumed to be constant in our scenario, which is ageneralization of f(R) gravity theories corresponding to the couplingQ=-1/sqrt{6}. We find that these models can be made compatible with localgravity constraints even when |Q| is of the order of unity through a chameleonmechanism, if the scalar-field potential is chosen to have a sufficiently largemass in the high-curvature regions. We show that these models generally lead tothe divergence of the equation of state of DE, which occur at smaller redshiftsas the deviation from the LambdaCDM model become more significant. We alsostudy the evolution of matter density perturbations and employ them to placebounds on the coupling |Q| as well as model parameters of the field potentialfrom observations of the matter power spectrum and the CMB anisotropies. Wefind that, as long as |Q| is smaller than the order of unity, there existallowed parameter regions that are consistent with both observational and localgravity constraints.

Constraints on scalar-tensor models of dark energy from observational and local gravity tests