Protective mechanisms used by the liverwort Marchantia polymorpha against abiotic stress

Jibran, R.1, Albert, N.W1, Zhou, Y.1, Schwinn, K.1, Bowman, J.2, Brummel, D.1, Jordan, B.3, Davies, K.1

The flavonoid pathway is hypothesised to have evolved for protection against abiotic stress during the period when plants were first colonising the land. In angiosperms, the colourless flavonols and flavones provide protection against excessive UVB-light, while anthocyanin pigments often accumulate in response to stress and may screen photosynthetic tissues from excess UVB light and/or scavenge reactive oxygen species. Little is known about the conservation of flavonoid functions and regulatory mechanisms outside of angiosperms. Liverworts are a basal land plant group. As such they can provide knowledge about plant characters that may have an ancient evolutionary origin: the species Marchantia polymorpha has been developed as a model system for such studies. We have shown ran association between flavones and UVB tolerance in marchantia. We are now examining the biosynthesis of the red flavonoid pigments of marchantia, the cell-wall-bound riccionidins, and their functions in abiotic stress tolerance.

We have identified an R2R3MYB transcription factor, MpMYB14, as the key activator of riccionidin biosynthesis and used this to produce marchantia plants with over-production (35S:MYB14) or loss (myb14 CRISPR mutants) of riccionidins. We have examined the production of riccionidins in response to stress and are now identifying candidate riccionidin biosynthetic genes using RNAseq, and testing their function using CRISPR mutagenesis. Our results suggest that stress-induced flavonoid pigment production is a character conserved across land plants as an early adaptation strategy for survival on land.

Presenting Author:  Rubina Jibran

Author Affiliation: 

1 New Zealand Institute of Plant and Food Research, Palmerston North, New Zealand.

2 Monash University, Melbourne, Australia.

3 Lincoln University, Christchurch, New Zealand