AUTHOR=Lai Chanjuan , Wang Jie , Kan Shenglong , Zhang Shuo , Li Pan , Reeve Wayne Gerald , Wu Zhiqiang , Zhang Yonghua 

TITLE=Comparative analysis of mitochondrial genomes of Broussonetia spp. (Moraceae) reveals heterogeneity in structure, synteny, intercellular gene transfer, and RNA editing

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1052151

DOI=10.3389/fpls.2022.1052151

ISSN=1664-462X

ABSTRACT=<p>The genus <italic>Broussonetia</italic> (Moraceae) is comprised of three non-hybrid recognized species that all produce high quality fiber essential in the development of papermaking and barkcloth-making technology. In addition, these species also have medicinal value in several countries. Despite their important economical, medicinal, and ecological values, the complete mitogenome of <italic>Broussonetia</italic> has not been reported and investigated, which would greatly facilitate molecular phylogenetics, species identification and understanding evolutionary processes. Here, we assembled the first-reported three complete <italic>Broussonetia</italic> (<italic>B. papyrifera</italic>, <italic>B. kaempferi</italic>, and <italic>B. monoica</italic>) mitochondrial genomes (mitogenome) based on a hybrid strategy using Illumina and Oxford Nanopore Technology sequencing data, and performed comprehensive comparisons in terms of their structure, gene content, synteny, intercellular gene transfer, phylogeny, and RNA editing. Our results showed their huge heterogeneities among the three species. Interestingly, the mitogenomes of <italic>B. monoica</italic> and <italic>B. papyrifera</italic> consisted of a single circular structure, whereas the <italic>B. kaempferi</italic> mitogenome was unique and consisted of a double circular structure. Gene content was consistent except for a few transfer RNA (tRNA) genes. The <italic>Broussonetia</italic> spp. mitogenomes had high sequence conservation but <italic>B. monoica</italic> with <italic>B. kaempferi</italic> contained more synteny blocks and were more related, a finding that was well-supported in organellar phylogeny. Fragments that had been transferred between mitogenomes were detected at plastome hotspots that had integrated under potential mediation of tRNA genes. In addition, RNA editing sites showed great differences in abundance, type, location and efficiency among species and tissues. The availability of these complete gap-free mitogenomes of <italic>Broussonetia</italic> spp. will provide a valuable genetic resource for evolutionary research and understanding the communications between the two organelle genomes.</p>