A cis‐acting bidirectional transcription switch controls sexual dimorphism in the liverwort

First author: Tetsuya Hisanaga; Affiliations: Nara Institute of Science and Technology (奈良先端科学技术大学院大学): Nara, Japan

Corresponding author: Keiji Nakajima

Plant life cycles alternate between haploid gametophytes (配子体) and diploid sporophytes (孢子体). While regulatory factors determining male and female sexual morphologies have been identified for sporophytic reproductive organs, such as stamens and pistils of angiosperms, those regulating sex‐specific traits in the haploid gametophytes that produce male and female gametes and hence are central to plant sexual reproduction are poorly understood. Here, we identified a MYB‐ ype transcription factor, MpFGMYB, as a key regulator of female sexual differentiation in the haploid‐dominant dioicous (雌雄异株) liverwort, Marchantia polymorpha. MpFGMYB is specifically expressed in females and its loss resulted in female‐ o‐male sex conversion. Strikingly, MpFGMYB expression is suppressed in males by a cis‐acting antisense gene SUF at the same locus, and loss‐of‐function suf mutations resulted in male‐ o‐female sex conversion. Thus, the bidirectional transcription module at the MpFGMYB/SUF locus acts as a toggle (转换键) between female and male sexual differentiation in M. polymorpha gametophytes. Arabidopsis thaliana MpFGMYB orthologs are known to be expressed in embryo sacs (胚囊) and promote their development. Thus, phylogenetically related MYB transcription factors regulate female gametophyte development across land plants.

植物的生命周期会在单倍体的配子体和二倍体的孢子体之间交替轮转。有关被子植物雄蕊和雌蕊等孢子体生殖器官的雄性、雌性性别形态决定的调控因子已经被鉴定出来，而对于植物有性生殖至关重要的单倍体配子体中能够产生雄性和雌性配子的性别特异性性状的调控因子还不是很了解。本文，作者鉴定到了一个MYB类转录因子MpFGMYB是控制单倍体占优势的雌雄异株植物地钱中雌性性别分化的关键调控因子。MpFGMYB特异性在雌性中表达，并且MpFGMYB的功能丢失会导致雌性向雄性性别的转换。有趣的是，MpFGMYB基因的表达在雄性中会被同一个位点的顺式反义基因SUF所抑制，并且功能缺失突变体suf会导致雄性向雌性性别的转换。因此，MpFGMYB/SUF位点的双向转录模块作为地钱配子体的雌性、雄性性别分化的“转换键”发挥作用。拟南芥的MpFGMYB同源基因在胚囊中表达，并且促进胚囊的发育。因此，陆地植物中系统发育上同源的MYB转录因子调控雌性配子体的发育。

doi: 10.15252/embj.2018100240

Journal: The EMBO Journal

Published online: 04 January, 2019