The sugar beet mitochondrial gene for the ATPase alpha-subunit: sequence, transcription and rearrangements in cytoplasmic male-sterile plants

Abstract

We have characterized the mitochondrial atpA (the alpha subunit of F1-ATPase) gene from male-fertile cytoplasm (cv TK81-0) of sugar beet. The gene is 1518-bp long and encodes a polypeptide of 506 amino acids. The atpA mRNA sequence is modified by three C-to-U RNA editing events, all of which alter the encoded protein sequences. In order to examine the genome organization of the atpA locus in cytoplasmic male-sterile (CMS) sugar beet, atpA-containing clones were isolated from Owen CMS (TK81-MS) and a different source of CMS [I-12CMS(2)] cytoplasm respectively. The sequences of the atpA coding region from TK81-MS and I-12CMS(2) are identical to each other and to the corresponding TK81-0 sequence. However, the TK81-0 and TK81-MS loci diverge completely 47 bp upstream of the initiation codon, resulting in different 5' transcript termini for the two genes. On the other hand, the point of divergence between the TK81-0 and I-12CMS(2) atpA genes was found to occur after 393 bp 3' to the TAA stop codon. Our results also show the 3'-flanking sequences of I-12CMS(2) atpA to be present elsewhere in the mitochondrial genomes of TK81-0, TK81-MS and I-12CMS(2), suggesting the possible involvement of these repeated DNA elements in the sequence rearrangements.

Phylogenetic relationships of the mitochondrial genomes in the genus Glycine subgenus Soja.

“…The membranes were washed twice with 6 M urea, 0.4% SDS and 0.5 × SSC for 20 min at 42°C, and twice with 2 × SSC for 5 min at room temperature. The membranes were used to expose X-ray films for 1-4 h. Five clones of mtDNA fragments were used as probes; a 1.5-kb EcoRI fragment that contained cox1 (a gene encoding subunit 1 of cytochrome oxidase) from sugar beet (Senda et al, 1991), a 0.7-kb NcoI-HindIII fragment that contained cox2 (a gene encoding subunit 2 of cytochrome oxidase) from soybean (Kato, 1996), a 0.7-kb StyI fragment that contained atp6 (a gene encoding subunit 6 of F 0 -ATPase) from Oenothera (Schuster and Brennicke, 1987), a 0.7-kb XhoI-EcoRV fragment that contained atp9 (a gene encoding subunit 9 of F 0 -ATPase) from pea (Morikami and Nakamura, 1987), and a 0.7-kb EcoRIBamHI fragment that contained atp1 (a gene encoding subunit 1 of F 1 -ATPase) from sugar beet (Senda et al, 1993). Phylogenetic analysis.…”

Differential screening of mitochondrial cDNA libraries from male-fertile and cytoplasmic male-sterile sugar-beet reveals genome rearrangements at atp6 and atpA loci

“…8). The D N A sequence ofc.2.9 kbp o f C M S m t D N A and 2.7 kb of M F m t D N A at the atpA locus was determined as described in Materials and methods and found to be identical to sequences reported recently by Senda et al [31]. The relevant sequence is summarized in Fig.…”

“…1). The precise location of 5' termini have been determined in high resolution mapping experiments [31,33] and are located upstream of a conserved 92 bp sequence in CMS and MF genotypes (Fig. 9); this sequence may play a role in the regulation of transcription and/or for translation of the atpA gene.…”

“…Differences in the genomic organization and transcription of CMS and male-fertile (MF) mtDNA have been identified by restriction enzyme mapping [24], heterologous probing [10] and limited DNA sequence analysis [30,31]. In addition, restriction enzyme mapping of overlapping cosmid clones of the mitochondrial genome of CMS sugar-beet has revealed a complex multicircular organization generated by homologous recombination across repeated DNA sequences derived from a putative 'master chromosome' of 386 kb [4].…”

Transcript processing internal to a mitochondrial open reading frame is correlated with fertility restoration in male‐sterile sorghum

“…This site is near the 3' terminus of a 70 bp region similar to rice atp6-orf79 (Akagi et al, 1994;Iwabuchi et al, 1993) (Figure 3), and the orflO7transcript terminus is within 4 bp of the transcript terminus of rice atp6-orf79. This region, and 3' flanking sequences, is also shared with sugar beet atpl (Senda et al, 1993;Xue et al, 1994), and the 3' terminus of the atpl transcript occurs at the same point (Senda etal., 1993). Thus orfl07, rice atp6-orf79, and sugarbeet atpl share sequence similarities at 3' transcript termini.…”