Genetic analysis of the liverwort Marchantia polymorpha reveals that R2R3MYB activation of flavonoid production in response to abiotic stress is an ancient character in land plants. Issue 2 (24th January 2018)

• Record Type: Journal Article
• Authors: Albert, Nick W.; Thrimawithana, Amali H.; McGhie, Tony K.; Clayton, William A.; Deroles, Simon C.; Schwinn, Kathy E.; Bowman, John L.; Jordan, Brian R.; Davies, Kevin M.
• Is Part Of: New phytologist. Volume 218:Issue 2(2018)
• Page Start: 554
• Page End: 566
• Publication Date: 2018-01-24
• Subjects: CRISPR/Cas9 -- evolution -- flavonoid -- liverwort -- MYB -- stress; Botany -- Periodicals; 580
• DOI: 10.1111/nph.15002
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: The flavonoid pathway is hypothesized to have evolved during land colonization by plants c . 450 Myr ago for protection against abiotic stresses. In angiosperms, R2R3MYB transcription factors are key for environmental regulation of flavonoid production. However, angiosperm R2R3MYB gene families are larger than those of basal plants, and it is not known whether the regulatory system is conserved across land plants. We examined whether R2R3MYBs regulate the flavonoid pathway in liverworts, one of the earliest diverging land plant lineages. We characterized Mp Myb14 from the liverwort Marchantia polymorpha using genetic mutagenesis, transgenic overexpression, gene promoter analysis, and transcriptomic and chemical analysis. Mp Myb14 is phylogenetically basal to characterized angiosperm R2R3MYB flavonoid regulators. Mp myb14 knockout lines lost all red pigmentation from the flavonoid riccionidin A, whereas overexpression conferred production of large amounts of flavones and riccionidin A, activation of associated biosynthetic genes, and constitutive red pigmentation. Mp Myb14 expression and flavonoid pigmentation were induced by light‐ and nutrient‐deprivation stress in M. polymorpha as for anthocyanins in angiosperms. Mp Myb14 regulates stress‐induced flavonoid production in M. polymorpha, and is essential for red pigmentation. This suggests that R2R3MYB regulated flavonoid production is a conserved character across land plants which arose early during land colonization.