PT  - JOURNAL ARTICLE
AU  - Taro Maeda
AU  - Yuuki Kobayashi
AU  - Hiromu Kameoka
AU  - Nao Okuma
AU  - Naoya Takeda
AU  - Katsushi Yamaguchi
AU  - Takahiro Bino
AU  - Shuji Shigenobu
AU  - Masayoshi Kawaguchi
TI  - Evidence of non-tandemly repeated rDNAs and their intragenomic heterogeneity in <em>Rhizophagus irregularis</em>
AID  - 10.1101/205864
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 205864
4099  - http://biorxiv.org/content/early/2018/03/26/205864.short
4100  - http://biorxiv.org/content/early/2018/03/26/205864.full
AB  - Arbuscular mycorrhizal fungus (AMF) species are one of the most widespread symbionts of land plants. Our substantially improved reference genome assembly of a model AMF, Rhizophagus irregularis DAOM-181602 (total contigs = 210), facilitated discovery of repetitive elements with unusual characteristics. R. irregularis has only ten or eleven copies of complete 45S rDNAs, whereas the general eukaryotic genome has tens to thousands of rDNA copies. R. irregularis rDNAs are highly heterogeneous and lack a tandem repeat structure. These findings provide evidence for the hypothesis that rDNA heterogeneity depends on the lack of tandem repeat structures. RNA-Seq analysis confirmed that all rDNA variants are actively transcribed. Observed rDNA/rRNA polymorphisms may modulate translation by using different ribosomes depending on biotic and abiotic interactions. The non-tandem repeat structure and intragenomic heterogeneity of AMF rDNA/rRNA may facilitate adaptation to a various environmental condition including the broad host range.