Isabel Monte, José M. Franco-Zorrilla, GloriaGarcía-Casado, Angel M. Zamarreño, José M. García-Mina, Ryuichi Nishihama, Takayuki Kohchi, Roberto Solano
Abstract
JAZ genes are negative regulators of jasmonate responses acting both as repressors of transcription factors and as co-receptors of JA-Ile. The high gene redundancy in angiosperms has hindered the characterization of a complete depletion of JAZ function. Moreover, the recent discovery that dn-OPDA is the jasmonate ligand in Marchantia polymorpha demonstrates that JA-Ile is not the sole COI1/JAZ ligand in land plants and underscores the importance of studying JAZ co-receptors in bryophytes. Here, we have exploited the low gene redundancy of the liverwort M. polymorpha to characterize the single MpJAZ in this early diverging plant lineage. We clarify the phylogenetic history of the TIFY family, demonstrate that MpJAZ is the ortholog of AtJAZ with a conserved function and characterize its repressor activity of dn-OPDA responses. Our results show that, consistent with previous findings in Arabidopsis, MpJAZ represses jasmonates biosynthesis, senescence and plant defences, and promotes cell-growth and reproductive fitness. The results also highlight the power of studies in Marchantia.