Whether it’s for orchids, berries, or bananas, plant tissue culture has been widely used in agriculture for nearly 40 years to produce uniform and disease-free stock. But when it comes to cannabis, this technology has only emerged within the last few years as scientists working with weed cracked the code of what the plant wants to reproduce successfully at a small scale. Joining in the fight against one of pot’s primary foes, hop latent viroid disease, cannabis tissue culture is a new path forward towards preserving the genetics of one of the most diverse botanicals on the planet. And, while cultivators have been able to get their hands on tissue culture-grown cuts for about eight years, tissue culture clones were made available to the public for the first time through Node Labs at the Emerald Cup Harvest Ball held in December 2022.
“Cannabis is a very tissue culture resistant plant. There are certain plants that are that way,” says Lauren Avenuis, CEO of Node Labs, explaining why it took so long for the technology to become viable for cannabis. “So, like avocados, grape vines, they just don’t like to go into micropropagation. They don’t like that kind of replication. And since cannabis is an annual plant, it likes to grow from a seed, flower, and die.”
The scientists working with Node, a small lab located within an unassuming red barn in rural Petaluma, California, spent years studying tissue culture before discovering the methodology that made stem cell technology for cannabis work. Now that they have, their facility houses an impressive bank of cannabis genetics. It causes a few snickers when I say it aloud, but being inside a room filled with shelves devoted to tissue culture clones, each in their own container, reminds me of being in a pet store aquarium. All the plants are growing within a clear jelly-like substance derived from seaweed called agar, allowing their whole root structure to be seen. They are tiny terrariums that hold the story of pot’s past, present, and future.
Chief Science Officer Chris Leavitt walks me through the procedures at Node by explaining that plants, unlike humans, do not have an awareness of their entire body.
“[Plants] are a colony of cells that are attached to each other,” Leavitt says. “So if a stem is receiving all the like sap that it would be getting normally in the agar, it doesn’t even know that it’s not still attached to the plant. You can grow plant parts in tissue culture in a way you cannot grow outside. You can grow a dissection of just a leaf or just a stem… you can really break the rules of typical plant growing by having it in that setting.”
My tour at Node starts in the pre-fab clean room where the media, the agar, is mixed within an autoclave, a device designed for sterilization. This room is also where the other tools used for the tissue culture process, such as scissors and jars, are sterilized. I put on a second set of surgical booties before heading into the growth chamber and transfer room, where I watch the hot agar being dispensed into the same clear plastic containers I see in the bulk food section of my local grocery store. Within this room, the air quality is at ISO 8, a measure that contains a thousand specks of dust within a cubic yard that is also used in electronic and medical manufacturing. All the sterilization and air cleanliness ensure no contamination enters the lab.
“One of the things that we do here is we clean plants,” says Luis Mautner, Node’s director of propagation. “Cleaning plants is a process by which you take a plant from the outside world and you run it through a process that we developed here. We select the plants that do not have any issues associated with them like pathogenic bacteria, fungi, fusarium being one of the ones that affects the cannabis industry very much. Also, we index for HLVd, which is hop latent viroid.”
Mautner started working with cannabis after a career in tissue culture that included work with the berry company Driscoll’s and tropical ornamental plants such as peace lilies. He says the clear media is used because it’s diagnostic and shows when things should not be growing on the plant.
Next, we enter another room where shelves store cannabis plants in various stages of growth. There are also shelves containing some other plants Node is testing for research, including wine grapes and the cutest tiny Tempranillo.
To start work with Node, clients provide 10 clone stems from a cannabis plant to form what Mautner calls a bouquet. The clones are broken down to the cellular level because cannabis has a strong affinity for endogenous contaminants within its stem, Leavitt explains. The scientists at Node cut the clones down to one part, the meristem, a type of tissue in plants that houses stem cells, or cells from which all other types of cells develop.
“What we’ve found is when you have the meristem dissection, you can avoid that,” Leavitt says.
“What you’re basically doing is taking [the cannabis clones] down to essentially the stem cells of the plant,” Avenius adds. “So you’re eliminating all of the epigenetic, all of the genetic toggles related to stress or environment. You’re getting [the plant] down to its pure expression, its genetics, and then also removing essentially all the vascular tissue. So you’re just getting a brand new pure example and sample of that cannabis plant that we can now grow into tissue culture free of any other influences and then see its pure genetic expression.”
When cut down to the meristem, the clones are only about half a millimeter to a millimeter in size. Once the plants grow bigger and start looking like cannabis plants instead of little blobs, they are tested for HLVd. HLVd is a widespread pathogen in cannabis clones that causes growth stunting and reduces the plant’s ability to produce trichomes. Leavitt explains that HLVd is like skin cancer in that it can affect one part of the plant, but not another. This is another reason tissue culture has been such a valuable tool in combating the virus because it reduces a plant to its most basic elements.
After the plants have passed the extensive screening process, they are grown to about 3 to 4 inches and are used to fill the bank, the system in which Node keeps cannabis genetics within a genetic library.
“These two refrigerators play a huge role in the large genetics cannabis market,” Avenius says as I eye Node’s genetic bank, containing work from cannabis breeders like Sherbinski and Masonic as well as companies like Cannarado, Connected, and smaller growers like Sonoma Hills Farm, which banked its Pink Jesus.
The seed bank aspect of the company ties into the beginnings of Node Labs. Node was founded in 2018 after Felipe Recalde, CEO of Compound Genetics and Node co-founder, lost his genetic library of cannabis cultivars and his home in the Tubbs Fire, the most destructive wildfire in California’s history that tore through Santa Rosa in 2017. Recognizing everyone around him had also lost their mom stock, Recalde saw tissue culture as the future for genetic preservation. He’d been experimenting with faulty kits for tissue culture since 2010. Still, it wasn’t until he partnered with Leavitt, who had been working on using tissue culture to preserve endangered species, that he saw that tissue culture could be viable for cannabis. Nowadays, genetics are stored within the lab and at a place offsite to serve as an additional backup against a disaster like a fire.
Some of the work Node does is private client services of storing the genetics, but some companies like Connected Cannabis Co. also have certified genetics available for licensing. The consistency of the tissue culture clones one receives from Node Labs ensures that brands that operate in many states, like one of the lab’s partners Khalifa Kush backed by rapper Wiz Khalifa, can provide standardized, consistent flowers across the country. Node’s primary partnership with Compound Genetics allows the lab to grow clones to flower for clients to test. The minds at Compound Genetics grow plants from seed in their San Francisco facility and phenohunt to provide the best clone selections for their clients. The process at Node gives the genetics an authentication that does not occur if someone obtains a clone cut from a friend.
The future of the tissue culture industry is not in creating a million plants to order, but instead holding genetics and delivering mother plants that growers can multiply through traditional propagation, Leavitt says.
“The main functionary of [tissue culture] here is not in micropropagation. It’s not to get you 50,000 plants in one go,” Leavitt explains of the difference in tissue culture techniques in cannabis versus traditional agriculture. “It’s germplasm storage, which is the fancy term in the agriculture issue of holding genetics, genetic banking.”
Another indication of the future of cannabis propagation occurring at Node Labs is the process of in vitro phenohunts or growing seeds within the agar jelly within test tubes. Node takes a tissue culture from small plantlets the seeds produce and grows those plants out, saving time for cultivators because if they like the results, the tissue culture already exists.
“It allows us to save a lot of time, but it also means that when we pop that seed and then we take that clone and put it out, we already have some of the advantages of tissue culture the first time we grow,” Avenuis says. “As an immature plant, it hasn’t been exposed to any viruses or pathogens. And then it has some of the unique morphology that you get from tissue culture plants. They tend to have higher vigor, higher yields, better stem strength. So you’re already seeing a better-performing plant from the very beginning.”
Leavitt points out an example within the lab, Gastro Pop #5, a cross of Apples & Bananas and Grape Gas which was developed in-house via an in vitro phenohunt.
“That Gastro Pop #5 over there, the plants in this lab have never seen microbial fungus and bacteria in their entire life,” Leavitt says.
If someone finds an outstanding cultivar they are in love with, a six-month process to get a tissue culture clone could stunt the excitement, he explains.
“With that process, in vitro, we could have the excitement of smoking the joint and going ‘This is the one’ and going, ‘Cool, it’s here at the lab’ at the same time,” he says.
An in vitro phenohunt is how Sherbinski and Compound created Tribute, a cross of Gelato #41 and Apples & Bananas. Look out for future collaborations between Compound Genetics and Tiki Madman and Compound Genetics and Green House Seed Company.
At the Emerald Cup Harvest Ball held in December 2022, Compound was able to offer “bare pulse” tissue culture clones of their newest offerings. These came without the agar jelly because the clones are more transportable that way. The bare pulse part comes from the fact that they are bare root or stored without soil around the roots. The bare pulse clones can be planted in a chosen medium and become a mother plant to power a grow with consistent genetics.
“We love this as the next gen of clones,” Avenuis says.
The whole process of tissue culture clones is an exciting new frontier for cannabis, one which I was able to experience firsthand when Recalde gifted me a tissue culture clone at a social gathering. I took the test tube, filled with a clone held in suspense within what I’ve since learned is agar, home and grew it out into a plant. At the time, I didn’t know that tiny plant contained within a test tube had the mighty makings to power a brand.
Read more about Node Labs in the upcoming Science & Technology issue of High Times Magazine.