Maize nuclear background regulates the synthesis of a 22-kDa polypeptide in Zea luxurians mitochondria.
When cytoplasm of the teosinte Zea luxurians is introduced into certain maize inbred nuclear backgrounds, the pattern of protein synthesis in the teosinte mitochondria is altered. Teosinte mitochondria purified from plants possessing a maize A619 nuclear background (Z.l.-A619 plants) synthesize a novel 22-kDa polypeptide that is associated exclusively with the membrane fraction of the organelle. Mitochondria from plants possessing a W23 nuclear background do not synthesize this protein. The F(1) hybrids Z.l.-A619 x W23 and Z.l.-W23 x A619 do not synthesize the protein. However, synthesis of the polypeptide was observed in 14 of 21 individual progeny from the backcross of the F(1) hybrid Z.l.-A619 x W23 to the pollen parent A619. These data suggest that a single nuclear gene controls the synthesis of the 22-kDa protein in mitochondria, with the recessive allele of the gene allowing expression of the polypeptide. Mitochondria from the F(1) hybrid Z.l.-A619 x Mo17 synthesize the 22-kDa protein, whereas mitochondria from Z.l.-A619 x B73 do not. Data from these outcrosses demonstrate that other maize lines also possess nuclear genes capable of regulating the synthesis of the 22-kDa Zea luxurians mitochondrial protein.
Division of Biological Sciences, University of Missouri, Columbia, MO 65211.
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Cooper
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Newton