Organization of mitochondrial DNA in normal and texas male sterile cytoplasms of maize

Abstract

Recombinant DNA and hybridization techniques have been used to compare the organization of mitochondrial DNA (mtDNA) from normal (N) and Texas male sterile (T) cytoplasms of maize. Bum H1 restriction fragments of normal mtDNA were cloned and used in molecular hybridizations against Southern blots of Bum H I digested N and T mtDNA. Fifteen of the 35 fragments were conserved in both N and T as indicated by hybridization to comigrating bands in their restriction patterns. Only three fragments produced autoradiographs whose differences could reasonably be attributed to single changes in the cleavage site of the enzyme while approximately half (17/35) of the clones resulted in more complicated differences between N and T. The autoradiographs produced by these 17 clones indicated multiple cleavage site changes and/or sequence rearrangements of the mtDNA. Patterns of six of these 17 clones indicated partial duplication of the sequence and two showed variation in the intensity of hybridization between N and T, which may be related to the molecular heterogeneity phenomenon found in maize mitochondrial genomes. The large proportion of changes observed between N and T rntDNA indicates that rearrangements may have played an important role in the evolution of the maize mitochondrial genome.

MAIZE MITOCHONDRIAL PLASMID S-1 SEQUENCES SHARE HOMOLOGY WITH CHLOROPLAST GENE psbA

“…The homologies were identifed by hybridizing a nick-translated 2.3-kb Hind111 restriction fragment from an internal region of S-1 with Southern blots containing BamHI digests of mtDNA and ctDNA from normal and cytoplasmic male-sterile (cms) lines of maize (Figure 2A). The variability of hybridization to the N, cms-S, and cms-T mtDNAs reflects differences in the relative stoichiometry and extent of the S-1 homologous sequences in the three mitochondrial genotypes (LEVINGS et SPRUILL, LEVINGS and SEDEROFF 1981;. The probe hybridizes to a 6.9-kb fragment in normal mtDNA that represents an integrated form of R-1 (LEVINGS et al.…”

Studies on the reproductive biology of male-sterile mutants of soybean (Glycine max (L.) Merr.)

“…Hybridization studies with cemigrating fragments indicated that extensive divergence of sequence organization distinguished cms-T from N cytoplasm (Spruill et al, 1981).…”

Nucleotide sequence of the S-1 mitochondrial DNA from the S cytoplasm of maize

“…It has been shown that nuclear background can influence the content and relative proportions of S-I and S-2 (Laughnan et al, 1981). Several studies have shown that mtDNA sequences from normal (fertile) and male-sterile cytoplasms share homology with S-1 and S-2 sequences (Spruill et al, 1980(Spruill et al, , 1981Lonsdale et al, 1981). Moreover, sequences homologous to S-1 are reported to occur in the maize nuclear genome .…”