C1HDZ transcription factor is critical for oil bodies formation and defense against arthropods in Marchantia polymorpha

BOWMAN JL; ROMANI F; MORENO JE; FLORENT SN

Cambridge

Simposio; Sainsbury Laboratory Symposium '20 Pluripotency in Plant Development; 2020

Sainsbury Laboratory, University of Cambridge

The Class I Homeodomain Leucine-Zipper (C1HDZ)transcription factors (TFs) modulate molecular responses to drought and othermolecular functions according to functional studies in angiosperms, but littleis known about its role in early-diverging land plants. We studied this geneclass in the model liverwort Marchantia polymorpha that encodes for a singleortholog of this gene. MpC1HDZ resembles all angiosperm C1HDZ structuralfeatures but, in contrast to flowering plants, we did not detect induction ofMpC1HDZ, nor the other gene members of the family, under ABA and osmotic stresstreatments. In the same way, loss-of-function Mpc1hdz plants showed nodifferential responses under abiotic stress treatments. Interestingly, Mpc1hdzplants showed developmental defects in oil body cells -idioblastic cells thataccumulate secondary metabolites. Consistently, we found that Mpc1hdz is highlyexpressed during early stages of oil body cell development. Moreover, ectopicoverexpression of MpC1HDZ is lethal for Marchantia, while in Arabidopsisinduced phenotypes like other C1HDZ gain-of-function plants, such as leafserration and drought tolerance. Altogether, this data is consistent with thenotion that the role of C1HDZ TFs in the water stress response of seed plantswas co-opted later in the evolution. C1HDZ TF family provides an example of howTF functionality diversified during land plant evolution.