Tissue culture is propagating plants from small pieces of tissue (shoot tips, nodes or meristems) placed on sterile nutrient gel containing sugars and plant growth regulators, in sealed containers under controlled light and temperature. It can multiply a genotype, produce pathogen-free plantlets and store genetics in a small space (Monthony et al. 2021).
In practice
For cannabis, tissue culture is mainly a preservation and clean-stock tool. A library of jars can hold many genotypes on a shelf, needing re-culture every few weeks to months instead of a room of mothers. Combined with meristem culture and testing, it is the main route to cleaning a cut of hop latent viroid.
It is demanding work. Sterile technique is essential, contamination from fungi and bacteria is common, and some cultivars multiply or root poorly. Regeneration from callus raises the risk of somaclonal variation, so preservation labs prefer shoot-tip or node culture and verify plantlets afterwards.
Don't confuse with
- Cloning (cuttings): rooting stem cuttings in a medium, non-sterile and simpler.
- Meristem culture: a specific tissue culture technique using the tiny growing tip.
- Genetic engineering: changing DNA; tissue culture alone does not.
The zone of dividing cells at the very tip of a shoot (or root) that produces new leaves, nodes and stem; removing it is what topping does.The genotype is the set of alleles a plant actually carries, either at one locus or across its whole genome, as opposed to the traits you can see.A mother plant is a female kept permanently in vegetative growth to supply cuttings, so a selected genotype can be propagated as clones indefinitely.Meristem culture is tissue culture from the tiny dome of dividing cells at a shoot tip, used to regenerate plants free of viroids and viruses.HLVd, a small infectious RNA that spreads through sap and tools, causing stunting, brittle stems, small loose buds and reduced resin in cannabis; called dudding.Re-veg is returning a flowering or harvested plant to vegetative growth by putting it back under long days, often to save a genotype after harvest.Somaclonal variation is genetic or epigenetic change that appears in plants regenerated from tissue culture, especially from callus, making them differ from the donor plant.Cloning is propagating a plant by rooting cuttings from it, producing new plants that are genetically identical to the donor.A clone-only is a cultivar that exists only as cuttings from one original plant, with no seed line that reliably reproduces it.Germplasm is living genetic material (seeds, pollen, tissue or plants) kept for breeding, research or conservation, representing the genetic diversity of a crop.A polyploid plant carries more than two full sets of chromosomes, such as a triploid (three) or tetraploid (four); in cannabis these are almost always bred deliberately.
