Plant egg cell fate determination depends on its exact position in female gametophyte

Significance In a mature female gametophyte of angiosperm, one egg cell and two synergid cells, referred to as the “egg apparatus,” originate from the same functional megaspore. How the egg cell and synergid cells differentiate into distinct cell types has drawn much attention but remains unclear. In this work, a live imaging system was established to visualize nuclear movement and cell specialization in female gametophytes. The final localization of the nuclei before cellularization was found to be critical for determining the cell fates of the egg apparatus. Artificial changes in the nuclear position could produce two functional egg cells. Furthermore, the plant hormone auxin was suggested as a positional cue for egg apparatus specialization.