Frequently Asked Questions

Traditional cuttings from mother plants have been the most popular method of propagating cannabis plants. It is a process that requires significant real estate, resources, and labor. Tissue culture can generate an almost infinite number of clones from one plant cutting. By limiting costs-per-square-foot (COGs / f2), Micropropagation is an effective tool to save space, labor, and time, thus increasing profit margins.

Plant tissue culture refers to the growing and multiplication of cells, tissues, and plants' organs on a defined solid or liquid media under an aseptic and controlled environment. Micropropagation of such plant tissue allows rapid production of high quality, virus- and disease-free, and uniform planting material. The micropropagation of high-quality planting material of ornamentals, forest, and fruit trees has created new opportunities in global trading for producers, farmers, nursery owners, and in rural employment.

Though plants can be multiplied under a controlled environment anywhere and irrespective of the season, weather, and on a year-round basis, Micropropagation technology is more expensive than the conventional plant propagation method. It is an initially capital-intensive industry. The strategy is to reduce production costs and lower the cost per plant (CPP).

Plant micropropagation is primarily based on the rapid proliferation of tiny stem cuttings, axillary buds, and to a limited extent of somatic embryos, which are cell clumps in suspension cultures. The cultured cells and tissue can take several pathways. The pathways that lead to the production of true-to-type plants in large numbers are the preferred ones for commercial multiplication.

The process of micropropagation is primarily divided into several stages:

1. Pre-propagation
2. Initiation of Explants
3. Subculture of Explants for Proliferation
4. Shooting and Rooting
5. Hardening.

These stages are universally applicable in large-scale multiplication of plants. The delivery of hardened small micro-propagated plants to growers and the market also requires extra care.

Early Health & Vigor

Tissue culture methods use sterilized vessels with sugar-rich media that support plantlets' growth before they can photosynthesize on their own. The media is prepped in the lab, poured into vessels (test tubes, Petri dishes, etc.), and placed in an autoclave / or pressure cooker where it is subjected to high temperatures and pressure to achieve proper sterility.

The sterile environment and rich growth media supply plantlets with an abundance of everything they need. When plantlets emerge from culture, they are pathogen-free, and nutrient reserves that support rapid growth and vigor are superior to conventional cuttings.

Stress and Disease

Diseases like powdery mildew and tobacco mosaic virus are often systemic, meaning that pathogens have spread to almost every tissue in the plant. Once infected, it is impossible to eliminate pathogens from tissues completely. Therefore, any cuttings made from a diseased mother plant will also be infected even if they look perfectly healthy. 

Tissue culture can eliminate the problem! Explants, or small tissue samples used as starting material, can be extracted from any plant part. Meristematic cells in shoot tips and leaves are the source of new plant growth. These cells and the first set of primordial leaves are not connected directly to the vascular tissue, allowing pathogens to spread by the plant’s transport system. Therefore, meristematic cells tend to be disease-free, whatever the condition of the mother. 

Since they can’t run from stress, plants react in the way of “change.” An infected plant will start to utilize its genes and begin making proteins that contribute to resistance. These gene expression changes are partly regulated by epigenetic modifications -- chemical changes to DNA that increase or decrease the likelihood a cell will express a particular gene but that do not modify the gene itself. 

Epigenetic modifications can be systemic and long-lived. Plants infected by a pathogen or stressed by drought will present widespread epigenetic changes in their DNA. In cannabis, those modifications are permanent. Thus, a cutting from a mother plant subject to drought or pathogen-adapted epigenetic programming will inherit that modified DNA and behave as if it were experiencing that stress, whether present or not. 

The epigenetic modifications allow mother plants to tolerate stress, which is great from the perspective of survival and fitness, but it comes at a cost. Some of the finite energy and resources that usually support plant growth and reproduction are instead channeled into a stress response. Those epigenetic changes result in a new phenotype for that mother. All cuttings from her will reflect the new phenotype. This is one major mechanism underlying what many in the cannabis industry incorrectly call "genetic drift," or the loss of vigor over successive clonal generations. 

To justify micropropagation, explants must be taken from Meristematic cells in shoot tips, and leaves are the source of new plant growth. These cells and the first set of primordial leaves are not connected directly to the vascular tissue, the plant’s transport system by which pathogens spread.

A virus-indexed variety is one that's been tested and deemed virus-free up until the point of testing.

Viruses are submicroscopic particles made up of protein and nucleic acid. They infect plant cells and use the plant’s nucleic acid replication systems to produce more viruses to interfere with plant growth. Common symptoms caused by viruses are leaf mosaic, twisting, distortion, chlorosis, yellowing, necrosis, stunting, or death.

Bacteria are microscopic, single-celled organisms. Most bacteria are culturable on artificial nutrient media and cause soft rot (decomposed plant tissue), blight (“scorched” lesions), wilt, or root rot.

There is a group of bacteria that isn't culturable on nutrient media called fastidious prokaryotes. Phytoplasmas are one type of particular bacteria that live in phloem sieve tubes of live plants and are transmitted by insect vectors. Typical symptoms of fastidious prokaryotes include witches’ broom, systemic yellowing, stunting, chronic decline, and abnormal growth.