  We discuss low-frequency g modes excited by resonant couplings with weakly
unstable oscillatory convective modes in the rotating convective core in
early-type main-sequence stars. Our non-adiabatic pulsation analyses including
the effect of Coriolis force for $2\,M_\odot$ main-sequence models show that if
the convective core rotates slightly faster than the surrounding radiative
layers, g modes in the radiative envelope are excited by a resonance coupling.
The frequency of the excited g mode in the inertial frame is close to
$|m\Omega_{\rm c}|$ with $m$ and $\Omega_{\rm c}$ being the azimuthal order of
the g mode and the rotation frequency of the convective core, respectively.
These g mode frequencies are consistent with those of photometric rotational
modulations and harmonics observed in many early-type main-sequence stars.
