Plant Thin Cell Layers: A 40-Year Celebration

The concept of a thin cell layer (TCL) was initially presented by Tran Thanh Van in two key papers exactly 40 years ago. At that time, Nicotiana tabacum was the model plant used to establish three main pathways for de novo organogenesis by developing a flower, vegetative bud, and root programme from pedicel tissue. Over the last 40 years, a wealth of research in plant tissue culture based on TCLs has emerged, fortifying the importance of this very simple technique, and highlighting its fundamental importance as a key tool in plant cell and tissue differentiation as well as organ development. This review not only highlights the achievements made using TCLs in the plant kingdom over these 40 years, it also reports on the success of this technique in ornamentals, fruit and forestry species, vegetables, and medicinal plants. There is overwhelming evidence of the importance of this technique for plant biotechnology, and it provides one solution for the mass clonal propagation of plants, use in bioreactors, genetic transformation, or micropropagation.