Originally published as Genetics Published Articles Ahead of Print on December 22, 2008.

Genetics, Vol. 181, 847-860, March 2009, Copyright © 2009
doi:10.1534/genetics.108.096859

The a2 Mating-Type Locus Genes lga2 and rga2 Direct Uniparental Mitochondrial DNA (mtDNA) Inheritance and Constrain mtDNA Recombination During Sexual Development of Ustilago maydis

Michael Fedler, Kai-Stephen Luh, Kathrin Stelter¹, Fernanda Nieto-Jacobo and Christoph W. Basse²

Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, D-35043 Marburg, Germany

² Corresponding author: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
E-mail: basse{at}mpi-marburg.mpg.de

Uniparental inheritance of mitochondria dominates among sexual eukaryotes. However, little is known about the mechanisms and genetic determinants. We have investigated the role of the plant pathogen Ustilago maydis genes lga2 and rga2 in uniparental mitochondrial DNA (mtDNA) inheritance during sexual development. The lga2 and rga2 genes are specific to the a2 mating-type locus and encode small mitochondrial proteins. On the basis of identified sequence polymorphisms due to variable intron numbers in mitochondrial genotypes, we could demonstrate that lga2 and rga2 decisively influence mtDNA inheritance in matings between a1 and a2 strains. Deletion of lga2 favored biparental inheritance and generation of recombinant mtDNA molecules in combinations in which inheritance of mtDNA of the a2 partner dominated. Conversely, deletion of rga2 resulted in predominant loss of a2-specific mtDNA and favored inheritance of the a1 mtDNA. Furthermore, expression of rga2 in the a1 partner protected the associated mtDNA from elimination. Our results indicate that Lga2 in conjunction with Rga2 directs uniparental mtDNA inheritance by mediating loss of the a1-associated mtDNA. This study shows for the first time an interplay of mitochondrial proteins in regulating uniparental mtDNA inheritance.

This article has been cited by other articles:

				M. Mahlert, C. Vogler, K. Stelter, G. Hause, and C. W. Basse The a2 mating-type-locus gene lga2 of Ustilago maydis interferes with mitochondrial dynamics and fusion, partially in dependence on a Dnm1-like fission component J. Cell Sci., July 15, 2009; 122(14): 2402 - 2412. [Abstract] [Full Text] [PDF]

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