Combine buttermilk and yeast in a 1-cup liquid measuring cup; let stand 5 minutes.
Combine all-purpose flour and next 5 ingredients in a large bowl. Cut in margarine with pastry blender until mixture is crumbly. Add buttermilk mixture and applesauce to flour mixture, stirring just until dry ingredients are moistened.
Turn dough out onto a lightly floured surface, and knead gently 3 or 4 times. Roll dough to 1/2-inch thickness; cut into rounds with a 2 1/2-inch biscuit cutter. Place rounds on a baking sheet coated with cooking spray; cover and let rise in a warm place (85º), free from drafts, 10 minutes. Bake at 400º for 10 to 12 minutes.