By Kara van der Berg
Many scientists believe that tissue culture is the future of horticulture. One of these researchers is John Driver, one of the biggest names in plant tissue culture in the world.
Driver was speaking from the Tissue Culture Facility (TCF) in Paarl, which he was visiting from California. Driver has been involved as a consultant with TCF since the start of the planning of the facility and has been an invaluable resource to them. It is his third trip to South Africa to see how the project is getting along.
Tissue culture – also called micropropagation – is a method by which fragments of tissue from a plant are transferred to an artificial sterile environment, on a growth medium in which they can optimally function.
“Tissue culture is a way that we can propagate a material – variety of rootstocks – that you can’t propagate in any other way,” explains Driver. “Historically, a lot of species aren’t able to root and so tissue culture provides a means through the technology of causing them to grow and root, and then they’re put back into the real world.”
Driver was an early pioneer of plant tissue culture with his interest being piqued in the 1980s. “My family had a nursery business. I was an undergrad at UC Davis and when I came back into the farm and nursery, I became aware that this technology was starting to evolve and develop. This eventually led me to start the first lab in California in 1981.”
The tissue culture media designed by Driver for walnut trees is one of the most used media for tree propagation in the world. He sold his last company in 2002 and now works as a consultant on tissue culture all over the world. SAPO Trust approached him to consult on the TCF project during the planning of the project.
Tissue culture is a rapid multiplication technique that can also create plants with desired characteristics, like being pest and disease resistant. For this reason, plants grown through the application of tissue culture have better yields. Rootstocks have for example been developed that are salt-tolerant and thus able to grow in areas where the soil’s salt content had not allowed it before.
“With the new rootstocks that are available [through tissue culture], you have the ability that they are disease-free, that they will grow where nematodes are, that they will control the stature of trees. So, you can now grow in soil you normally couldn’t grow in.”
Micropropagated plants are observed to establish more quickly, grow more vigorously, have a more uniform production cycle, and produce higher yields than conventionally propagated plants. Despite all these attractive attributes, many growers and nurseries are still sceptical of tissue culture methods. Many people, especially nurseries, are scared that their value chains may be disrupted by the introduction of tissue culture. TCF aims to sell the new rootstocks to nurseries who in turn propagate trees to sell to the growers.
Driver explains that he experienced the same pushback in California 40 years ago. Though tissue culture was dominant in Europe at the time, it took 15 to 20 years for it to catch on in America as it was regarded as ‘disruptive’.
“It’s been a real evolutionary process. I had a vision a long time ago and there was considerable opposition to it in the nursery industry. But the growers then started demanding these rootstocks. Because of that, tissue culture then became the predominant means of production of rootstocks.”
Today, almost everything in the US is either produced by tissue culture directly or tissue culture-derived material.
Driver believes that acceptance of tissue culture may happen faster in South Africa, as the technology is not new. “I believe it could take as short as five to six or up to ten tears until everyone here thinks this is the direction we should go.”
The biggest obstacle in tissue culture is developing the chemical media that the plants grow on, which can take years to achieve. The walnut materials Driver started in California took about 20 years before all the bugs got out of that system. For TCF, the process has been made easier as Driver brought a host of media with him as part of the consultancy agreement. TCF and Driver just had to adapt the media to the lab, which Driver says should be a short process.
Tissue culture is more expensive to produce than for instance seed, however, Driver explains that there are greater financial returns in the long run for growers such as longer life of an orchard and less disease pressure. “It is a tool that is going to help us to expand the range of tree growing in areas where we may have problems. It gives us a greater range of material.”
TCF is an initiative driven by the South African deciduous fruit industry, including Hortgro Stone, Hortgro Pome, the Canning Producers’ Association, the South African Table Grape Industry, Raisins SA, and SAPO Trust, and received an R10 million grant from the Western Cape Department of Agriculture. The initiative hopes to push the South African deciduous fruit industry to keep up with international trends and to establish best international practices locally.
The facility hopes to address the shortage of available rootstocks in the country. At the moment, TCF is focusing on apple rootstocks, clonal stone fruit rootstocks, cherries, blueberries, and vines but hopes to branch out into other fruit types later.
“I think for tissue culture to be successful; it requires that people have a vision for what they want to achieve and then push forward. Once the growers start to get the new rootstocks that will benefit their situation, then you’ll find that all the nurseries will also want those products because that’s what their growers want.”
Caption: The tissue culture team at Bernheim with TC-guru John Driver. From left, Sane van Wyk (lab assistant), John Driver, Charmaine Stander (lab manager), and Leander Gagiono (nursery manager).