Evolution of an unstable sex determination system in white Guinea yam (Dioscorea rotundata)

Aoi Kudoh; Yu Sugihara; Kohtaro Iseki; Ryo Matsumoto; Koki Minoji; Kiyoshi Onai; Akira Abe; Satoshi Natsume; Toshiyuki Sakai; Kaori Oikawa; Motoki Shimizu; Kazue Itoh; Hiroaki Adachi; Kodai Honda; Shinşuke Yamanaka; Paterne Angelot Agre; Patrick Olusanmi Adebola; Asrat Asfaw; Ryohei Terauchi

doi:10.64898/2026.09.08.750133

Plant BiologybioRxivSep 11, 2026

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Evolution of an unstable sex determination system in white Guinea yam (Dioscorea rotundata)

Aoi Kudoh iD, Yu Sugihara iD, Kohtaro Iseki iD, Ryo Matsumoto iD, Koki Minoji iD, Kiyoshi Onai iD, Akira Abe iD, Satoshi Natsume iD, Toshiyuki Sakai iD, Kaori Oikawa, Motoki Shimizu iD, Kazue Itoh, Hiroaki Adachi iD, Kodai Honda iD, Shinşuke Yamanaka iD, Paterne Angelot Agre iD, Patrick Olusanmi Adebola iD, Asrat Asfaw iD, Ryohei Terauchi iD

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Abstract

Plants often produce unstable sex phenotypes; however, the underlying evolutionary and molecular mechanisms are unclear. In white Guinea yam (Dioscorea rotundata), the most economically important tuber crop, genetic improvement is critical for food security but remains constrained by dioecy and complex sex phenotypes. White Guinea yam has a ZZ/ZW sex determination system in which ZZ individuals are consistently male, whereas ZW individuals can be female, male, or monoecious. Here we show that chromosome 11 is the sex chromosome, featuring a 1.2-Mb inversion between the Z and W chromosomes. A 170-kb W-specific region carries the microRNA gene dro-MIR432, likely involved in sex switching. The recent emergence of this miRNA-mediated ZZ/ZW system, distinct from the XY/XX system within Dioscorea, underscores the dynamic evolution of plant sex determination.