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Most cytoplasmic male sterility systems are associated with the expression of novel mitochondrial open reading frames. This male sterility can often be overcome by the action of specific nuclear restorer genes, which alter the expression of the cms-associated open reading frames. The T-urf13 mitochondrial gene causes T cytoplasm maize to be male sterile. This sterility can be overcome by the combined action of two nuclear genes, one of which, rf2, does not affect the expression of T-urf13. Instead, as Liu et al. demonstrate on pages 1063­1078, rf2 encodes a mitochondrial aldehyde dehydrogenase. Because mtALDHs can oxidize many aldehydes, the mechanism by which this enzyme functions to restore fertility is not known. As shown on the cover, mtALDH activity is required for anther development in the lower florets of maize spikelets, even in normal cytoplasm plants. Hence, it appears that an existing gene was recruited to serve as a nuclear restorer of cmsT.