Organ geometry channels reproductive cell fate in the Arabidopsis ovule primordium.

In multicellular organisms, sexual reproduction requires the separation of the germline from the soma. In flowering plants, the female germline precursor differentiates as a single spore mother cell (SMC) as the ovule primordium forms. Here, we explored how organ growth contributes to SMC differentiation.

H3.1 Eviction Marks Female Germline Precursors in Arabidopsis.

In flowering plants, germline precursors are differentiated from somatic cells. The female germline precursor of is located in the internal (nucellar) tissue of the ovule, and is known as the Megaspore Mother Cell (MMC). MMC differentiation in occurs when a cell in the subepidermal layer of the nucellar apex enters the meiotic program.

A Multigenic Network of ARGONAUTE4 Clade Members Controls Early Megaspore Formation in Arabidopsis.

The development of gametophytes relies on the establishment of a haploid gametophytic generation that initiates with the specification of gametophytic precursors. The majority of flowering plants differentiate a single gametophytic precursor in the ovule: the megaspore mother cell. Here we show that, in addition to argonaute9 (ago9), mutations in other ARGONAUTE (AGO) genes such as ago4, ago6, and ago8, also show abnormal configurations containing supernumerary gametophytic precursors in Arabidopsis thaliana Double homozygous ago4 ago9 individuals showed a suppressive effect on the frequency of ovules with multiple gametophytic precursors across three consecutive generations, indicating that genetic interactions result in compensatory mechanisms.