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

FLORENT SN; BOWMAN JL; ROMANI F; UEDA T; KANAZAWA T; MORENO JE

Buenos Aires

Simposio; Simposio Fronteras en Biociencia 3; 2019

IBIOBA

Colonization of land by plants and subsequent radiation are major evolutionaryevents in earth history that required the evolution of the plant body as well asnovel plant traits. Land plants had to cope with a dryer and harmful habitat,including competition with other organisms. At the genome level, this transitionwas accompanied by an increment of transcription factors (TFs) genes, crucialfor the environmental gene response regulation. Bryophytes pioneeredterrestrial colonization. Marchantia polymorpha is an extant bryophyte thataccumulates terpene compounds in specific organelles called ?oil bodies?.Though oil bodies function and regulation are still not clear, it was proposedthey play a role in the plant response to biotic and abiotic stress.In order to understand the ancestral role of class I HOMEODOMAIN LEUCINEZIPPER(C1HDZ) genes in plants, we generated Marchantia mutants lacking afunctional protein (mpc1hdz). We found that mpc1hdz develops smaller gemmacups with abnormal morphology and few oil bodies in thallus and gemmae. Totest the putative roles of oil bodies, we used different conditions related toabiotic and biotic stress. Our preliminary data suggested that they might not beinvolved in abiotic stress, since mpc1hdz responses were similar to wild-typeplants under NaCl and cold treatments and water-loss experiments. However,feeding assays with pill-bugs showed a significant preference for mutant plantsrather than the wild-type, suggesting that oil bodies are important for Marchantiadefense. In addition, a transcriptome analysis of mpc1hdz plants showedconstitutive repression of Terpene Synthases genes and induction of LateEmbryogenesis Abundant genes.All together, we provide functional evidence supporting a role for the ancestralMpC1HDZ TF controlling the development of gemmae cups and oil bodies, twotraits no longer conserved in angiosperms. We propose that MpC1HDZ is acase of exaptation of a TF during land plants evolution.