Book Description

In an effort to study the interactions between nuclear and mitochondrial genomes, crosses between recently diverged species have been used to produce progeny that have altered phenotypes. Plants possessing teosinte cytoplasms of Zea perennis (Zp), diploperennis or luxurians and the nuclear genome of the main W23 inbred line are fertile, but pale in color, developmentally retarded, and they produce markedly small kernels. This phenotype, referred to as "teosinte-cytoplasm-associated miniature" (TCM), is maternally inherited in crosses between W23 inbred line and plants carrying the Zp teosinte cytoplasm with the W23 nuclear background (ZpW23). A dominant allele of a single nuclear locus, Rcm ("Rectifier-of-cytoplasmic-miniature") restores normal growth to TCM plants. In this research, two-dimensional SDS-polyacrylamide gel electrophoresis and immunoblot analysis with a maize mitochondrial porin antibody suggest that there is a reduction of porin isoforms in the ZpW23 homozygous recessive (rcm / rcm) plants in comparison to near-isogenic heterozygous (Rcm / rcm) siblings. RFLP mapping of shows dud one maize porin gene and the Rcm locus are closely linked on chromosome 7. It is proposed that the Rcm locus either encodes a porin or is a linked regulatory factor. In either cam, the nuclear encoded porins must successfully interact with a mitochondrially coded factor(s) for normal plant growth and development A second aspect of this research is the characterization of the porin gene family of maize. item are at least five maize nuclear genes coding for the porins present in the mitochondrial outer membrane. These loci appear to be orthologous to three wheat isoforms previously identified.