Tissue Culture
Do you know how your weed was grown? Historically, the only options were seeds and clones, as in plants germinated from seeds or clones cut from a mother plant and grown. Today we want to focus on a new growing method that could be a game changer in the industry: Tissue Culture. In order to better understand why Tissue Culture is such an attractive cultivation method, let’s first discuss some of the benefits and drawbacks of growing from seeds or clones first.
Most home growers and many breeders will often grow their plants from seeds. For home growers, this is because getting clones can be difficult, especially if they live in a state where cannabis is not yet legal. It also provides a true feeling of craftsmanship taking a plant from seed to bud which cannot be discounted. Professional cultivators, on the other hand, are able to discover new phenotypes through seeds. They are a lot like a box of chocolates - you never know what you’re gonna get. Seed popping and pheno hunting go hand in hand. This is also one of the drawbacks for other growers however, as they must also be able to produce higher quantities of the same flower which is impossible to do if you only grow from seeds. Additionally, starting from seeds can take quite a bit longer than clones or tissue culture which is not ideal when trying to grow in volume.
Up until now, cloning has been the go-to method used by cultivators to mass produce identical copies of the same phenotype. To do this, a mother plant is chosen and kept in its vegitative (non-flowering) state, from which stalks are cut off and replanted as clones. However, this process is not without its drawbacks. For starters, tending to the mother plant can be quite time consuming and challenging. Great care must be taken to ensure that the plant remains in this vegitative state while also not succumbing to a myriad of issues like plant degradation, viruses, or other genetic defects. This is extremely important as all the clones taken will be genetically identical to the mother plant - any genetic defects included.
Sometimes also referred to as micropropagation, Tissue Culture was a technique first developed in 1907 and is a broad term used to describe the method of taking cells from a parent organism and growing them in a controlled environment, sometimes called an artificial medium. This technique has been utilized in agriculture for years, with plant tissue cultures being used to create many identical copies of a mother plant without many of the drawbacks found in traditional cloning methods. However, due to the high level of precision and technology needed to utilize Tissue Culture, it has not traditionally been used in cannabis - until now. How exactly does this process work? Like cloning, it all starts with selecting a mother plant. The goal here is to find the plant whose exact phenotype you wish to replicate, this being the plant with the most desired traits. From here, the cultivator then locates and removes apical or axillary meristems in nodal cuttings. There are two apical meristems in cannabis, one on the top of the plant (the shoot), and one on the bottom (the root). There are many other axillary meristems as well, these being the newest growths of the plant and they are all loaded with meristem cells, which are cells that have the ability to both replicate and turn into the cells of any other part of the plant, meaning that you can grow an entirely new plant from just these nodal cuttings. These nodal cuttings are each put into a vessel with an artificial growing medium to help them grow aseptically and can be considered like small clones. After a few weeks, the new explants created from this process are then transferred to a new vessel, where they begin to root in order to prepare them for harsher, more natural growing environments. Finally, these explants are acclimated into the garden to grow into the full beautiful flowering buds we love. Why go through this whole process? There are many reasons, but perhaps the biggest is the ability to store cultivars in a small sterile vessel that requires less maintenance than a plant in the garden. This process is also faster than growing from seeds and more efficient and scalable than cloning.
Finally, while our focus is on micropropagation, there is another type of Tissue Culture that focuses specifically on the shoot or root apical meristem known as meristem regeneration. This refers to the ability to take a handful of meristem cells and grow a new plant with just these cells. The main benefit of this process is that this technique can potentially remove viruses found within the mother plant, producing genetically superior clones. As the industry grows, we’re excited to take advantage of new techniques that help us put quality over everything.
