抄録
The sexual life cycle in plants generally consists of a haploid
gametophyte and a diploid sporophyte, both of which appear reciprocally at
temporally different stages via fertilization of gametes to produce
sporophytes and meiosis to produce gametophytes. The red seaweeds
Bangiales display a heteromorphic sexual life cycle containing a leafy
gametophyte (thallus) and a filamentous sporophyte (conchocelis). Unlike
other multicellular eukaryotes, the production of gametophytic spores,
termed conchospores, in a conchosporangium is not associated with meiosis
in Bangiales. To explore this question, we performed transcriptomic
profiling of Pyropia yezoensis gametophytes, sporophytes and
conchosporangia and identified a knotted-like homeobox gene that is
predominately expressed in the conchosporangium and may determine its
identity. Further, spore-like single cells isolated from conchosporangia
developed directly into thalli. We therefore concluded that gametophytic
identity is established in the conchosporangium before release of
conchospores without meiosis and proposed a triphasic life cycle in P.
yezoensis where apospory is responsible for production of
gametophyte generation.
