Submitted to: Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/16/1996
Publication Date: N/A
Citation: Interpretive Summary: Maize hybrids have a significant yield advantage over open-pollinated varieties. Hybrids are produced by cross pollinating two inbred lines. One way of producing hybrid seed efficiently is through the use of cytoplasmic male-sterile (cms) germplasm. Since cms plants do not produce viable pollen, they are unable to cross pollinate other plants. This is an advantage because it eliminates the need for the time and labor intensive task of hand emasculation of the inbred lines. Most cms systems also have restorer genes which correct the defect of male sterility. By using a combination of characterized cytoplasmic male-sterile plants and plants which contain nuclear restorer genes, one can produce hybrid seed effectively. However, our understanding of the molecular mechanisms by which restoration occurs has been hampered by the lack of cloned nuclear restorer genes. In this manuscript, we report the cloning and characterization of the rf2 nuclear restorer gene from maize. This achievement represents the first isolation of nuclear restorer of cms from any species in the plant kingdom and provides a unique opportunity to test hypotheses regarding the molecular mechanism by which fertility restoration occurs. Since cytoplasmic male sterility plays an important role in breeding programs, a basic understanding of the role of this restorer gene on pollen fertility will impact U.S. Agriculture by improving the science of crop production. This is timely because cytoplasmic male sterility is again becoming an economically important component of commercial maize breeding programs and continues to be important in other species.
Technical Abstract: Fertility restoration in male-sterile, T-cytoplasm (cmsT) maize requires the action of two nuclear genes. Using a transposon tagging approach, we have cloned one of these genes, rf2. Based on the finding that rf2 encodes a putative aldehyde dehydrogenase (ALDH), two mechanisms are proposed to explain Rf2-mediated fertility restoration of cmsT. It is suggested that either ALDH is involved in the detoxification of acetaldehyde and/or ethanol produced via ethanolic fermentation during pollen development or that ALDH interacts directly or indirectly with URF13, the mitochondrial protein that is associated with male sterility in cmsT.