Skip to main content

Asymmetric cell division of Arabidopsis Zygote

Final Activity Report Summary - ACDAZ (Asymmetric Cell Division of Arabidopsis Zygote)

Asymmetric cell division generates two daughter cells that adopt different developmental fates and are often different in size. This vital type of cell division occurs in a wide range of organisms, from bacteria and yeasts to plants and animals, and plays crucial roles during multicellular development. Although post-embryonic development predominates in higher plants such as arabidopsis, the basic body plan is established during embryogenesis and, during this stage, the very first asymmetric cell division is crucial for all subsequent development. The arabidopsis zygote divides asymmetrically to give an apical and a basal daughter cell. The apical daughter cell produces two tiers, each consisting of four cells, which find the apical and central regions of the embryo that give rise to the shoot meristem and hypocotyl. The basal daughter cell produces a file of six to nine cells of which all, but the uppermost one, form the suspensor. The uppermost cell of the file becomes the hypophysis, or founder cell of the basal region of the embryo from which the root meristem originates.

The aim of this project was to characterise the asymmetric cell division of the zygote and the establishment of apical versus basal cell fate at the molecular level. We identified specific markers that were exclusive to the embryo and to the apical or basal lineage and were necessary to generate a high-resolution transcriptional map. In addition, we identified a negative regulator of bodenlos (BDL) expression and a positive regulator of both monopteros (MP) and BDL expression. As such, our novel and exciting results shed new light on the role of auxin in patterning and showed that auxin-independent transcriptional regulation of Aux/IAA proteins was crucial for embryonic patterning and plant growth, which represented a novel concept in plant developmental biology.