  Studying the internal structure of exoplanets-host stars compared to that of
similar stars without detected planets is particularly important for the
understanding of planetary formation. The observed overmetallicity of stars
with planets may be a hint in that respect. Although it is obviously related to
the physical processes which occur during the early phases of planetary
formation, the origin of this overmetallicity is unclear. It may be either
primordial or related to accretion processes or both. In this framework,
asteroseismic studies represent an excellent tool to determine the structural
differences between stars with and without detected planets. The two different
missions of COROT are linked in this programme: the detection of new planets
and the seismic studies of their host stars share the same goal of a better
understanding of planetary formation and evolution. The COROT main target
HD52265, which is known to host at least one giant planet, will be observed
continuously during five months: many interesting results are expected from
this long run. Meanwhile, stellar oscillations will be searched for in all
stars around which new planets will be discovered.
