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UVR8‐mediated induction of flavonoid biosynthesis for UVB tolerance is conserved between the liverwort Marchantia polymorpha and flowering plants
Author(s) -
Clayton William A.,
Albert Nick W.,
Thrimawithana Amali H.,
McGhie Tony K.,
Deroles Simon C.,
Schwinn Kathy E.,
Warren Ben A.,
McLachlan Andrew R.G.,
Bowman John L.,
Jordan Brian R.,
Davies Kevin M.
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14044
Subject(s) - marchantia polymorpha , biology , flavonoid biosynthesis , chalcone isomerase , photomorphogenesis , myb , hypocotyl , mutant , flavonoid , botany , genetics , biochemistry , arabidopsis , chalcone synthase , biosynthesis , transcriptome , gene , transcription factor , gene expression , antioxidant
Summary Damaging UVB radiation is a major abiotic stress facing land plants. In angiosperms the UV RESISTANCE LOCUS 8 ( UVR 8) photoreceptor coordinates UVB responses, including inducing biosynthesis of protective flavonoids. We characterised the UVB responses of Marchantia polymorpha (marchantia), the model species for the liverwort group of basal plants. Physiological, chemical and transcriptomic analyses were conducted on wild‐type marchantia exposed to three different UVB regimes. CRISPR /Cas9 was used to obtain plant lines with mutations for components of the UVB signal pathway or the flavonoid biosynthetic pathway, and transgenics overexpressing the marchantia UVR 8 sequence were generated. The mutant and transgenic lines were analysed for changes in flavonoid content, their response to UVB exposure, and transcript abundance of a set of 48 genes that included components of the UVB response pathway characterised for angiosperms. The marchantia UVB response included many components in common with Arabidopsis, including production of UVB ‐absorbing flavonoids, the central activator role of ELONGATED HYPOCOTYL 5 ( HY 5), and negative feedback regulation by REPRESSOR OF UV ‐B PHOTOMORPHOGENESIS 1 ( RUP 1). Notable differences included the greater importance of CHALCONE ISOMERASE ‐ LIKE ( CHIL ). Mutants disrupted in the response pathway ( hy5 ) or flavonoid production ( chalcone isomerase , chil ) were more easily damaged by UVB . Mutants ( rup1 ) or transgenics ( 35S:Mp MYB 14 ) with increased flavonoid content had increased UVB tolerance. The results suggest that UVR 8‐mediated flavonoid induction is a UVB tolerance character conserved across land plants and may have been an early adaptation to life on land.