The liverwort oil body is formed by redirection of the secretory pathway

Abstract

Eukaryotic cells acquired novel organelles during evolution through mechanisms that remain largely obscure. The existence of the unique oil body compartment is a synapomorphy of liverworts that represents lineage-specific acquisition of this organelle during evolution, although its origin, biogenesis, and physiological function are yet unknown. We find that two paralogous syntaxin-1 homologs in the liverwort Marchantia polymorpha are distinctly targeted to forming cell plates and the oil body, suggesting that these structures share some developmental similarity. Oil body formation is regulated by an ERF/AP2-type transcription factor and loss of the oil body increases M. polymorpha herbivory. These findings highlight a common strategy for the acquisition of organelles with distinct functions in plants, via periodical redirection of the secretory pathway depending on cellular phase transition.

Plant SYP12 syntaxins mediate an evolutionarily conserved general immunity to filamentous pathogens

“…In contrast to PEN1 and SYP122 in Arabidopsis , MpSYP12A seems to be essential in Marchantia , thereby precluding the possibility for studying preinvasive immunity in knockout lines ( Kanazawa et al, 2020 ). Instead, to evaluate whether the immunity function of the SYP12 clade is evolutionarily conserved among land plants, we introduced GFP-fused versions of the two Marchantia SYP12s (i.e., MpSYP12A and MpSYP12B) into the Arabidopsis pen1 syp122 mutant.…”

“…At a later stage of plant evolution, PEN1 has acquired an additional specialization needed for powdery mildew resistance, which could explain its distinctive subcellular localization ( Nielsen and Thordal-Christensen, 2012 ; Nielsen and Thordal-Christensen, 2013 ). Interestingly, in Marchantia , MpSYP12A locates to the plasma membrane and seems vital for cell plate formation, whereas MpSYP12B locates to a type of oil body unique to liverworts ( Kanazawa et al, 2016 ; Kanazawa et al, 2020 ). This indicates yet another functional specialization of the SYP12 clade similar to that which occurred in Arabidopsis .…”

miniTurbo-based interactomics of two plasma membrane-localized SNARE proteins in Marchantia polymorpha

“…This indicates that we were able to capture a number of undescribed potential interactors of MpSYP12A and MpSYP13B, respectively. Kanazawa et al . (2020) were able to show that MpSYP12A but not MpSYP13B localized to the phragmoplast during cell plate formation by using fluorescent reporter-lines.…”

“…In M. polymorpha , the two SNARE (soluble N- ethylmaleimide-sensitive factor attachment protein receptor) proteins, MpSYP12A and MpSYP13B, are plasma membrane- localized and ubiquitously expressed throughout the thallus (Kanazawa et al ., 2016; Kanazawa et al ., 2020). Plant SNAREs modulate membrane-trafficking, intra- and intercellular signalling, and transport.…”

“…Carella et al (2018 reported that MpSYP13B accumulated in haustoria-like structures upon infection of M. polymorpha with the oomycete pathogen Phytophthora palmivora. Recently, MpSYP12A was shown to localize to the phragmoplast during cell plate formation (Kanazawa et al, 2020). Interaction partners of SYP1 family proteins in M. polymorpha have not yet been identified.…”