Plant Biotechnology
Online ISSN : 1347-6114
Print ISSN : 1342-4580
ISSN-L : 1342-4580
Original Papers
IRE1-mediated cytoplasmic splicing and regulated IRE1-dependent decay of mRNA in the liverwort Marchantia polymorpha
Sho TakedaTaisuke TogawaKei-ichiro MishibaKatsuyuki T. YamatoYuji IwataNozomu Koizumi
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Supplementary material

2022 Volume 39 Issue 3 Pages 303-310


The unfolded protein response (UPR) or the endoplasmic reticulum (ER) stress response is a homeostatic cellular response conserved in eukaryotes to alleviate the accumulation of unfolded proteins in the ER. In the present study, we characterized the UPR in the liverwort Marchantia polymorpha to obtain insights into the conservation and divergence of the UPR in the land plants. We demonstrate that the most conserved UPR transducer in eukaryotes, IRE1, is conserved in M. polymorpha, which harbors a single gene encoding IRE1. We showed that MpIRE1 mediates cytoplasmic splicing of mRNA encoding MpbZIP7, a M. polymorpha homolog of bZIP60 in flowering plants, and upregulation of ER chaperone genes in response to the ER stress inducer tunicamycin. We further showed that MpIRE1 also mediates downregulation of genes encoding secretory and membrane proteins in response to ER stress, indicating the conservation of regulated IRE1-dependent decay of mRNA. Consistent with their roles in the UPR, Mpire1ge and Mpbzip7ge mutants exhibited higher sensitivity to ER stress. Furthermore, an Mpire1ge mutant also exhibited retarded growth even without ER stress inducers, indicating the importance of MpIRE1 for vegetative growth in addition to alleviation of ER stress. The present study provides insights into the evolution of the UPR in land plants.

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© 2022 Japanese Society for Plant Biotechnology

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