A bidirectional switch controls sexual dimorphism in the liverwort (EMBO J)

Bryophytes spend most of their lifecycle in the haploid, gametophytic form, of which there are two types, male (sperm forming) and female (egg forming). Hisanaga et al. investigated the genetic basis that determines sex in the model liverwort Marchantia polymorpha. Their findings are fascinating. A single genetic locus acts as a switch, to specify either male or female form. MpFGMYB encodes a transcription factor specifically expressed in females; loss-of-function alleles cause a female-to-male conversion. In males, the opposite DNA strand is transcribed, producing a long non-coding RNA that silences MpFGMYB. This system thus acts as a toggle, switching the organism into either the male or female state. (Summary by Mary Williams)  EMBO J. 10.15252/embj.2018100240