The paperpresent preliminary results of a crossing program followed byembryoculture in vitro. The program included the female line HA89 (cms) and various American wild species (mostly perennials). Thirty-four interspecific hybrids have been made and 481 plants successfully regenerated, i. e., the âverâge regeneration rate of 54.3% has been achieved. Presently, the hybrid progenies are being identified morphologically. cytologically, by isozyme electrophoresis and/or by RFLP analysis. They will be backcrossed and tested against available restorers. When new CMS materials are made, they will be scrcened for resistance to Sclerotinia selerotiorum and Botrytis cinerea.