MySQL 5.5 Release Notes
The same system time zone should be set for both master and
slave. Otherwise, statements depending on the local time on the
master are not replicated properly, such as statements that use
the NOW() or
FROM_UNIXTIME() functions. You
can set the time zone in which MySQL server runs by using the
--timezone=
option of the timezone_namemysqld_safe script or by
setting the TZ environment variable. See also
Section 17.4.1.14, “Replication and System Functions”.