Basic Concepts of Tissue Culture

Four concepts anchor the whole of plant tissue culture. Totipotency is the foundational one: it is the genetic potential every living, nucleated plant cell carries to develop, when placed in a suitable nutrient medium, into a complete individual plant. Because a differentiated cell such as a leaf or stem cell already carries a full copy of the plant's genome, tissue culture works by giving that cell the chance to switch its developmental programme back on.

Differentiation is the process by which a relatively unspecialised cell undergoes biochemical and structural change to become a specialised cell suited to a particular form and function - a xylem vessel element, a guard cell, a sieve tube, and so on. Under normal development this process runs in one direction, but tissue culture routinely reverses and then re-triggers it. …