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Ancient mitochondrial haplotypes and evidence for intragenic recombination in a gynodioecious plant.

ABSTRACT: Because of their extremely low nucleotide mutation rates, plant mitochondrial genes are generally not expected to show variation within species. Remarkably, we found nine distinct cytochrome b sequence haplotypes in the gynodioecious alpine plant Silene acaulis, with two or more haplotypes coexisting locally in each of three sampled regions. Moreover, there is evidence for intragenic recombination in the history of the haplotype sample, implying at least transient heteroplasmy of mitochondrial DNA (mtDNA). Heteroplasmy might be achieved by one of two potential mechanisms, either continuous coexistence of subgenomic fragments in low stoichiometry, or occasional paternal leakage of mtDNA. On the basis of levels of synonymous nucleotide substitutions, the average divergence time between haplotypes is estimated to be at least 15 million years. Ancient coalescence of extant haplotypes is further indicated by the paucity of fixed differences in haplotypes obtained from related species, a pattern expected under trans-specific evolution. Our data are consistent with models of frequency-dependent selection on linked cytoplasmic male-sterility factors, the putative molecular basis of females in gynodioecious populations. However, associations between marker loci and the inferred male-sterility genes can be maintained only with very low rates of recombination. Heteroplasmy and recombination between divergent haplotypes imply unexplored consequences for the evolutionary dynamics of gynodioecy, a widespread plant breeding system.

SUBMITTER: Stadler T

PROVIDER: S-EPMC129337 | biostudies-literature | 2002 Sep

REPOSITORIES: biostudies-literature

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Ancient mitochondrial haplotypes and evidence for intragenic recombination in a gynodioecious plant.

Städler Thomas T Delph Lynda F LF

Proceedings of the National Academy of Sciences of the United States of America 20020821 18

Because of their extremely low nucleotide mutation rates, plant mitochondrial genes are generally not expected to show variation within species. Remarkably, we found nine distinct cytochrome b sequence haplotypes in the gynodioecious alpine plant Silene acaulis, with two or more haplotypes coexisting locally in each of three sampled regions. Moreover, there is evidence for intragenic recombination in the history of the haplotype sample, implying at least transient heteroplasmy of mitochondrial D ...[more]

PMID: 12192087

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Project description:Mitochondrial genes and genomes have patterns of inheritance that are distinctly different from those of nuclear genes and genomes. In nature, the mitochondrial genomes in eukaryotes are generally considered non-recombining and homoplasmic. If heteroplasmy and recombination exist, they are typically very limited in both space and time. Here we show that mitochondrial heteroplasmy and recombination may not be limited to a specific population nor exit only transiently in the basidiomycete Cantharellus cibarius and related species. These edible yellow chanterelles are an ecologically very important group of fungi and among the most prominent wild edible mushrooms in the Northern Hemisphere. At present, very little is known about the genetics and population biology of these fungia cross large geographical distances. Our study here analyzed a total of 363 specimens of edible yellow chanterelles from 24 geographic locations in Yunnan in southwestern China and six geographic locations in five countries in Europe. For each mushroom sample, we obtained the DNA sequences at two genes, one in the nuclear genome and one in the mitochondrial genome. Our analyses of the nuclear gene, translation elongation factor 1-alpha (tef-1) and the DNA barcode of C. cibarius and related species, suggested these samples belong to four known species and five potential new species. Interestingly, analyses of the mitochondrial ATP synthase subunit 6 (atp6) gene fragment revealed evidence of heteroplasmy in two geographic samples in Yunnan and recombination within the two new putative species in Yunnan. Specifically, all four possible haplotypes at two polymorphic nucleotide sites within the mitochondrial atp6 gene were found distributed across several geographic locations in Yunnan. Furthermore, these four haplotypes were broadly distributed across multiple phylogenetic clades constructed based on nuclear tef-1 sequences. Our results suggest that heteroplasmy and mitochondrial recombination might have happened repeatedly during the evolution of the yellow chanterelles. Together, our results suggest that the edible yellow chanterelles represent an excellent system from which to study the evolution of mitochondrial-nuclear genome relationships.

Dataset Information

Ancient mitochondrial haplotypes and evidence for intragenic recombination in a gynodioecious plant.

Publications

Ancient mitochondrial haplotypes and evidence for intragenic recombination in a gynodioecious plant.

Similar Datasets

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