Preheat oven to 350°.
To prepare cake, lightly spoon 1 1/2 cups flour into dry measuring cups, and level with a knife. Combine with 1/4 cup wheat germ, baking powder, and baking soda in a large bowl. Combine the sour cream, 1/2 cup brown sugar, applesauce, oil, and egg in a bowl; stir well with a whisk. Add to flour mixture, stirring just until moist. Fold in the dried cranberries. Spoon batter into a 9-inch round cake pan coated with cooking spray.
To prepare streusel topping, combine 1/4 cup wheat germ, 2 tablespoons flour, 2 tablespoons brown sugar, and cinnamon in a small bowl; cut in margarine with a pastry blender or 2 knives until mixture resembles coarse meal. Sprinkle streusel topping evenly over batter. Bake at 350° for 50 minutes or until a wooden pick inserted in center comes out clean. Cool the cake on a wire rack.