Complex sentence: Corn plants with T-cms cytoplasm have maternally inherited the gene T-urf 13, which encodes for a protein component of the inner mitochondrial membrane that functions as T-toxin's site of action.
Split into simpler sentences: Corn plants with T-cms cytoplasm have maternally inherited the gene T-urf 13, which encodes for a protein component of the inner mitochondrial membrane. This portion of the membrane functions as T-toxin's site of action.