Utility of in vitro culture to the study of plant mitochondrial genome configuration and its dynamic features.

Peibei Sun,Maria P Arrieta-Montiel,Sally A Mackenzie

doi:10.1007/s00122-012-1844-4

Abstract

Recombination activity plays an important role in the heteroplasmic and stoichiometric variation of plant mitochondrial genomes. Recent studies show that the nuclear gene MSH1 functions to suppress asymmetric recombination at 47 repeat pairs within the Arabidopsis mitochondrial genome. Two additional nuclear genes, RECA3 and OSB1, have also been shown to participate in the control of mitochondrial DNA exchange in Arabidopsis. Here, we demonstrate that repeat-mediated de novo recombination is enhanced in Arabidopsis and tobacco mitochondrial genomes following passage through tissue culture, which conditions the MSH1 and RECA3 suppressions. The mitochondrial DNA changes arising through in vitro culture in tobacco were reversible by plant regeneration, with correspondingly restored MSH1 transcript levels. For a growing number of plant species, mitochondrial genome sequence assembly has been complicated by insufficient information about recombinationally active repeat content. Our data suggest that passage through cell culture provides a rapid and effective means to decipher the dynamic features of a mitochondrial genome by comparative analysis of passaged and non-passaged mitochondrial DNA samples following next-generation sequencing and assembly.

Highlights

The plant mitochondrial genome is organized into an unusual multipartite structure derived from high and low frequencyCommunicated by M
Our data suggest that passage through cell culture provides a rapid and effective means to decipher the dynamic features of a mitochondrial genome by comparative analysis of passaged and non-passaged mitochondrial DNA samples following next-generation sequencing and assembly
Callus-inducing medium for Arabidopsis consists of basic Murashige and Skoog (1962) supplemented with 1 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D), 0.5 mg L-1 benzylaminopurine (BAP), 1 mg L-1 1-Naphthyl acetic acid (NAA), 1 mg L-1 Indole-3-acetic acid (IAA), 3 % sucrose and 0.8 % washed agar (Sigma) with pH 5.7 ± 0.1

Summary

Introduction

The plant mitochondrial genome is organized into an unusual multipartite structure derived from high and low frequencyCommunicated by M. The plant mitochondrial genome is organized into an unusual multipartite structure derived from high and low frequency. DNA recombination between repeated sequences in the genome (Fauron et al 1995). Large-sized ([1,000 bp) repeats participate in high-frequency reciprocal DNA exchange to subdivide the genome and facilitate inter-conversions between DNA molecules (Mackenzie and McIntosh 1999). Intermediate-sized (50–550 bp) repeats mediate low frequency asymmetric DNA exchange that results in accumulation of only one of the expected recombinant products (Shedge et al 2007). Frequency of DNA exchange at these intermediate repeats appears to control the relative copy number of the recombinant forms within the genome

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Conclusion