Meristem culture is a tissue culture technique that starts from the apical meristem: the dome of actively dividing cells at the very tip of a shoot, often under 0.5 mm with one or two leaf primordia. Because many viroids and viruses are absent or scarce in this tissue, plants regenerated from it can be free of an infection that the mother carries.
In practice
It is the main method of cleaning cannabis clones infected with hop latent viroid. The meristem is excised under magnification in sterile conditions, grown on gel into a plantlet, multiplied, then tested. Success is not guaranteed: some plantlets still carry the pathogen, so each line must be tested (often more than once) before it is called clean. Combining meristem culture with heat or cold treatment can improve elimination rates in other cropsbeing reviewed.
Meristem culture keeps organised tissue, so the risk of somaclonal variation is lower than with callus-based methods.
Don't confuse with
- Tissue culture (general): can use nodes, leaves or callus, not just the meristem.
- Meristem (anatomy): the growing tissue itself; meristem culture is the lab technique.
Myth check
A tired old cut is usually sick, not mutated or drifted. Cleaning it through meristem culture and testing often restores its vigour. See hop latent viroid and viruses.
Tissue culture is growing small pieces of a plant on sterile nutrient gel in a sealed vessel, used to multiply, clean up and store cannabis genotypes.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 first individual flowers that form at stem nodes during late vegetative growth, letting a grower tell male from female before full flowering.The smallest known plant pathogen: a short circular RNA, usually 246-401 nucleotides, with no protein coat and no protein-coding genes, copied by the host's own enzymes.An infectious particle of nucleic acid in a protein coat that replicates inside plant cells; on cannabis, often insect-spread and incurable once infected.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.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.A clone-only is a cultivar that exists only as cuttings from one original plant, with no seed line that reliably reproduces it.Genetic drift is random change in allele frequencies between generations of a seed population, strongest in small populations; clones do not drift this way.
