XVI International Botanical Congess

Patterns of organization of the root apical meristem of Arabidopsis thaliana and Trifolium repens will be discussed. One common event, a T-division, leads to the initiation of the epidermis and peripheral root cap even though these roots have different apical organization. This suggests a common developmental pathway for the epidermis and peripheral root cap from initiation to maturation. The peripheral root cap and epidermal cells are produced from periclinal T-divisions of the root cap protoderm (RCP) initial cells. Lineages derived from each initial cell were followed in A. thaliana and T. repens root tips. Subsequent proliferative divisions of cell lineages forming 'packets' of epidermal and peripheral root cap cells, and their relation to the columella root cap cells will be described.