Dataset Information

Intragenomic polymorphism and intergenomic recombination in the ribosomal RNA genes of strains belonging to a yeast species Pichia membranifaciens.

ABSTRACT: A concerted evolution model has been proposed to explain the observed lack of sequence variation among the multiple ribosomal RNA (rRNA) gene copies in many different eukaryotic species. Recent studies on the level of intragenomic variations in the rRNA gene repeats of fungi resulted in controversial conclusions. In this study, we clearly showed that significant polymorphisms of the internal transcribed spacers (ITS1 and ITS2) of ribosomal DNA (rDNA) exist within the genome of a strain of the yeast species Pichia membranifaciens. More interestingly, we showed that the intragenomic ITS sequence polymorphisms were formed by intergenomic rDNA recombination among different P. membranifaciens strains with significantly different ITS sequences. Intergenomic rDNA recombination was also responsible for the diversification of rDNA sequences in different strains of the species. After the events bring together different rDNA types in individual genomes of the P. membranifaciens strains compared, rDNA sequence heterogeneity has remained in the genome of one but eliminated by homogenisation in the genomes of other strains. Our findings show new clue for further investigation on the mechanism of concerted evolution of rRNA genes in eukaryotes.

SUBMITTER: Wu ZW

PROVIDER: S-EPMC6059064 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Intragenomic polymorphism and intergenomic recombination in the ribosomal RNA genes of strains belonging to a yeast species <i>Pichia membranifaciens</i>.

Wu Zuo-Wei ZW Wang Qi-Ming QM Liu Xin-Zhan XZ Bai Feng-Yan FY

Mycology 20160711 3

A concerted evolution model has been proposed to explain the observed lack of sequence variation among the multiple ribosomal RNA (rRNA) gene copies in many different eukaryotic species. Recent studies on the level of intragenomic variations in the rRNA gene repeats of fungi resulted in controversial conclusions. In this study, we clearly showed that significant polymorphisms of the internal transcribed spacers (ITS1 and ITS2) of ribosomal DNA (rDNA) exist within the genome of a strain of the ye ...[more]

PMID: 30123622

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Project description:Background and aimsBananas (Musa spp.) are a major staple food for hundreds of millions of people in developing countries. The cultivated varieties are seedless and parthenocarpic clones of which the ancestral origin remains to be clarified. The most important cultivars are triploids with an AAA, AAB or ABB genome constitution, with A and B genomes provided by M. acuminata and M. balbisiana, respectively. Previous studies suggested that inter-genome recombinations were relatively common in banana cultivars and that triploids were more likely to have passed through an intermediate hybrid. In this study, we investigated the chromosome structure within the ABB group, composed of starchy cooking bananas that play an important role in food security.MethodsUsing SNP markers called from RADSeq data, we studied the chromosome structure of 36 ABB genotypes spanning defined taxonomic subgroups. To complement our understanding, we searched for similar events within nine AB hybrid genotypes.Key resultsRecurrent homologous exchanges (HEs), i.e. chromatin exchanges between A and B subgenomes, were unravelled with at least nine founding events (HE patterns) at the origin of ABB bananas prior to clonal diversification. Two independent founding events were found for Pisang Awak genotypes. Two HE patterns, corresponding to genotypes Pelipita and Klue Teparod, show an over-representation of B genome contribution. Three HE patterns mainly found in Indian accessions shared some recombined regions and two additional patterns did not correspond to any known subgroups.ConclusionsThe discovery of the nine founding events allowed an investigation of the possible routes that led to the creation of the different subgroups, which resulted in new hypotheses. Based on our observations, we suggest different routes that gave rise to the current diversity in the ABB cultivars, routes involving primary AB hybrids, routes leading to shared HEs and routes leading to a B excess ratio. Genetic fluxes took place between M. acuminata and M. balbisiana, particularly in India, where these unbalanced AB hybrids and ABB allotriploids originated, and where cultivated M. balbisiana are abundant. The result of this study clarifies the classification of ABB cultivars, possibly leading to the revision of the classification of this subgroup.

Dataset Information

Intragenomic polymorphism and intergenomic recombination in the ribosomal RNA genes of strains belonging to a yeast species Pichia membranifaciens.

Publications

Intragenomic polymorphism and intergenomic recombination in the ribosomal RNA genes of strains belonging to a yeast species <i>Pichia membranifaciens</i>.

Similar Datasets

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