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Properties and nucleotide sequence of a mitochondrial plasmid from sunflower
D Crouzillat1, L Gentzbittel, L de la Canal
1Laboratoire de Phytomorphogenèse UA CNRS 45, Université Blasie Pascal, Clermont-Ferrand, France.
Abstract:
The 1.413 circular supercoiled mitochondrial DNA plasmid P1 from a fertile sunflower line was sequenced, and a series of 160 bp tandemly repeated sequences was observed. The P1 plasmid was detected in both fertile and cytoplasmic male-sterile (CMS) lines, but in different quantities. Two other circular plasmids, P2 and P3, each 1.8 kbp in length, were shown to share common sequences with P1. The mitochondrial plasmid P1 detected homologous sequences in the nuclear DNA of sunflower, but not in chloroplast DNA nor in main band mitochondrial DNA. RNA molecules of about 680 and 550 nucleotides were detected that were complementary to mt plasmid P1.
Insights
Sunflower mitochondrial DNA contains a plasmid (P1) with repeating sequences, found in both fertile and sterile lines. This plasmid shares sequences with other mitochondrial plasmids and has homologous regions in nuclear DNA.
Area of Science:
- Plant molecular biology
- Mitochondrial genetics
- Sunflower genomics
Background:
- Mitochondrial DNA (mtDNA) in plants can exist as plasmids, influencing cellular functions.
- Cytoplasmic male sterility (CMS) in sunflowers is often associated with mitochondrial abnormalities.
Purpose of the Study:
- To sequence and characterize the mitochondrial DNA plasmid P1 from a fertile sunflower line.
- To investigate the presence and distribution of P1 in fertile and CMS sunflower lines.
- To explore potential origins and interactions of P1 with other DNA components.
Main Methods:
- DNA sequencing of the circular mitochondrial plasmid P1.
- Plasmid detection and quantification in different sunflower genotypes using molecular techniques.
- Southern blot analysis to detect homologous sequences in nuclear, chloroplast, and main band mtDNA.
- Northern blot analysis to detect RNA molecules complementary to P1.
Main Results:
- The 1.413 kbp mitochondrial plasmid P1 contains tandemly repeated sequences.
- P1 is present in both fertile and cytoplasmic male-sterile (CMS) sunflower lines, but at varying levels.
- Two other plasmids (P2, P3) share sequences with P1.
- Homologous sequences to P1 were found in sunflower nuclear DNA, but not in chloroplast or main band mtDNA.
- RNA molecules complementary to P1 were detected.
Conclusions:
- Sunflower mitochondria harbor unique plasmids with potential roles in plant physiology.
- The differential abundance of P1 in fertile and CMS lines suggests a link to sterility phenotypes.
- The presence of homologous sequences in nuclear DNA indicates possible horizontal gene transfer or integration events.