Trigonometric Calogero-Moser System as a Symmetry Reduction of KP   Hierarchy
  Trigonometric non-isospectral flows are defined for KP hierarchy. It is demonstrated that symmetry constraints of KP hierarchy associated with these flows give rise to trigonometric Calogero-Moser system. 
L.V. Bogdanov, B.G. Konopelchenko and A.Yu. Orlov