Peñuelas et al. uncover the surprising functional conservation of jasmonate-related MYC transcription factors in liverwort. Plant Cell (2019) https://doi.org/10.1105/tpc.19.00974
Background: Jasmonoyl-isoleucine (JA-Ile) is a lipid-derived plant hormone that regulates immunity, growth, and development in vascular plants. Non-vascular plants such as liverworts do not synthesize JA-Ile and use a different molecule (dinor-OPDA) to activate similar processes.
Question: Although JA-Ile and dinor-OPDA share conserved receptors, the transcription factors (TFs) that activate responses to dinor-OPDA in basal plant lineages are currently unknown.
Findings: Peñuelas et al. identified the TFs responsible for the genome-wide transcriptional reprogramming induced by dinor-OPDA in the liverwort Marchantia polymorpha. These TFs are evolutionarily related to the MYC TFs that regulate responses to JA-Ile in the eudicot Arabidopsis thaliana. The results suggest that MYC function first appeared in charophycean algae and therefore predates the evolutionary appearance of any other jasmonate pathway component. Therefore, despite 450 million years of independent evolution, MYCs are functionally conserved between bryophytes and eudicots. Genetic conservation in an early diverging lineage suggests that MYC function existed in the common ancestor of land plants and evolved from a pre-existing MYC function in charophycean algae.
Next steps: The identification of these TFs in Marchantia polymorpha will facilitate the elucidation of new regulatory mechanisms of this pathway, which are a challenge to identify in eudicots due to their more complex genomes, where gene redundancy hinders genetic analysis.
María Peñuelas, Isabel Monte, Fabian Schweizer, Armelle Vallat, Philippe Reymond, Gloria García-Casado, Jose M. Franco-Zorrilla, and Roberto Solano (2019). Jasmonate-related MYC Transcription Factors are Functionally Conserved in Marchantia polymorpha. Plant Cell 31: xxx. https://doi.org/10.1105/tpc.19.00974
Key words: Marchantia polymorpha, MYC transcription factors, evolution, functional conservation, jasmonic acid