Zygnema circumcarinatum UTEX 1559 chloroplast and mitochondrial genomes provide insight into land plant evolution

Author ORCID Identifier

Lauren Orton:https://orcid.org/0000-0003-2372-5277

Publication Title

Journal of Experimental Botany

ISSN

00220957

E-ISSN

14602431

Document Type

Article

Abstract

The complete chloroplast and mitochondrial genomes of Charophyta have shed new light on land plant terrestrialization. Here, we report the organellar genomes of the Zygnema circumcarinatum strain UTEX 1559, and a comparative genomics investigation of 33 plastomes and 18 mitogenomes of Chlorophyta, Charophyta (including UTEX 1559 and its conspecific relative SAG 698-1a), and Embryophyta. Gene presence/absence was determined across these plastomes and mitogenomes. A comparison between the plastomes of UTEX 1559 (157 548 bp) and SAG 698-1a (165 372 bp) revealed very similar gene contents, but substantial genome rearrangements. Surprisingly, the two plastomes share only 85.69% nucleotide sequence identity. The UTEX 1559 mitogenome size is 215 954 bp, the largest among all sequenced Charophyta. Interestingly, this large mitogenome contains a 50 kb region without homology to any other organellar genomes, which is flanked by two 86 bp direct repeats and contains 15 ORFs. These ORFs have significant homology to proteins from bacteria and plants with functions such as primase, RNA polymerase, and DNA polymerase. We conclude that (i) the previously published SAG 698-1a plastome is probably from a different Zygnema species, and (ii) the 50 kb region in the UTEX 1559 mitogenome might be recently acquired as a mobile element.

First Page

3361

Last Page

3373

Publication Date

6-11-2020

DOI

10.1093/jxb/eraa149

Keywords

Charophyte green algae, chloroplast, embryophyta, evolution, genomes, land plants, mitochondria, mitogenome, plastome, terrestrialization, Zygnema

Department

Department of Biological Sciences; Institute for the Study of the Environment, Sustainability, and Energy (Environmental Studies)

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