Initiation of asexual reproduction by the AP2/ERF gene GEMMIFER in Marchantia polymorpha

Plants can propagate their own clones through asexual reproduction. Genetic and hormonal factors regulating asexual reproduction have begun to be elucidated in the liverwort Marchantia polymorpha, which produce asexual propagules called gemmae within the gemma cups. Here, we report an AP2/ERF family gene, GEMMIFER (MpGMFR), as a key regulator of asexual reproduction in M. polymorpha. Suppression of MpGMFR function using genome editing and amiRNA results in the loss of gemma and gemma cup formation. In contrast, activation of MpGMFR function using a dexamethasone inducible system promotes gemma and/or gemma cup formation depending on the induction conditions. Notably, transient strong activation of MpGMFR induced gemma initial cells at the meristem, which develop into mature gemmae capable of reproducing as new individuals after detachment. These results show that MpGMFR is necessary and sufficient for the initiation of asexual reproduction at the meristem. MpGMFR expression was detected from the meristem through to the early stages of gemma development including the gemma cup floor cells. MpGMFR expression precedes the expression of GEMMA CUP-ASSOCIATED MYB1 (MpGCAM1) in early gemma development, supporting the notion that MpGMFR initiates asexual reproduction. We anticipate this finding to be a foundation to study the evolution of extra meristem formation in plant bodies that may have made a significant contribution to the prosperity of plants on land.