Inheritance of large mitochondrial RNA's in alfalfa

Several large RNA molecules that migrated to electrophoretic positions ranging from 1.7-10 kb were observed in preparation of alfalfa (Medicago sativa) mitochondria. F₁ progenies inherited the RNA's from both maternal and paternal parents (Fig. 1). Treatment of intact mitochondria with RNase A failed to remove the RNA's, indicating that they were contained within an RNase impermeable compartment. Further purification of mitochondria in linear sucrose gradients failed to separate the RNA's from mitochondria. Transmission electron microscopic examination of sucrose gradient purified mitochondria revealed that mitochondria were free of contamination by virus-like particles, indicating that the RNA's were contained within the mitochondrion. Biparental inheritance of large mitochondrial RNA's in alfalfa provides evidence that mitochondria are inherited biparentally in this species.