Mutations at specific atp6 codons which cause human mitochondrial diseasesalso lead to male sterility in a plant

Defects in the human mitochondrial genetic system result in some diseases. These disorders are the result of rearrangements or point mutations in mito chondrial genes. In higher plants mutations and rearrangements in the mitoc hondrial DNA are believed to cause cytoplasmic male sterility (CMS), a mito chondrially inherited inability to produce viable pollen. In sorghum, forma tion of CMS is strongly correlated with anther-specific loss of mitochondri al atp6 RNA editing. Here we show that this loss of atp6 RNA editing mimics point mutations at codons that cause severe disorders in humans. We conclu de that (i) loss of RNA editing in sorghum anthers probably causes CMS, (ii ) similarities exist in the onset of mitochondrial dysfunction in plant and human tissues, and (iii) the evolutionary appearance of RNA editing provid ed a mechanism to compensate for otherwise lethal point mutations. (C) 1998 Federation of European Biochemical Societies.