Seven types of plant tissue culture, explained

"Tissue culture" is an umbrella term. Depending on which part of the plant you start with and what you want at the end, the method changes quite a lot. Here are the main types you will come across.

1. Meristem culture

The meristem is the tiny dome of dividing cells at a shoot tip, often less than a millimetre across. Because viruses spread slowly into this zone, culturing just the meristem is a classic way to recover virus-free plants. Often combined with heat treatment (thermotherapy) for better results.

2. Shoot tip and nodal culture

The workhorse of commercial micropropagation. Larger shoot tips or single-node pieces are cultured on a medium rich in cytokinin, which pushes them to form many side shoots. These are split and subcultured repeatedly.

3. Callus culture

Callus is an unorganised mass of cells that forms when tissue is exposed to high auxin levels. It can be kept growing indefinitely and later coaxed into shoots or roots. Useful for research and for producing plant compounds, but plants regenerated from callus can show more genetic variation, so it is used carefully for clonal work.

4. Somatic embryogenesis

Here body (somatic) cells are persuaded to form embryos, just like those in a seed but genetically identical to the parent. It can be scaled up in liquid systems and is used for crops like coffee, oil palm and conifers.

5. Anther and pollen culture

Culturing anthers or isolated pollen grains produces haploid plants, which carry one set of chromosomes. Doubling those chromosomes gives completely uniform, pure lines in one generation — a big shortcut for breeders.

6. Cell suspension culture

Single cells or small clumps grown in shaken liquid medium. Mostly used to study plant biology or to produce valuable secondary metabolites in bioreactors.

7. Protoplast culture

Enzymes strip away the cell wall, leaving naked protoplasts. These can be fused to combine species that won't cross normally, or used for gene editing. Technically demanding and mostly a research tool.