Polyploid grafting refers to a process where grafting techniques (or joining two plants into one) are used to create polyploid plants (or ones with more than two sets of chromosomes) by combining genetic material from different species.
This technology is enjoying growing interest as generating plants with increased chromosome can enhance traits like stress tolerance, growth vigor, and productivity, ultimately producing plants that are better equipped to handle the impacts of climate change.
But despite the potential, longstanding questions remain as to the technology’s commercial viability and whether other agricultural science advances – specifically GM crops – may have a similar impact.
Iyris CTO Daniel Bryant says a major development recently occurred with a patent filed for one of the most promising applications of the technology by one of the company’s founders, Professor Mark Tester.
This newly patented polyploid hybridization grafting process stems from decades of research led by Tester at King Abdullah University of Science and Technology (KAUST) and was inspired by resilient wild tomato relatives found in extreme environments, in this case the Galapagos Islands.
The process mimics and accelerates natural evolutionary mechanisms to breed genetic resilience into plant rootstocks, enabling crops to thrive in stressful abiotic environments such as high temperatures, drought, salinity, and pest-prone conditions.
“One of the keys to Tester’s breakthroughs was to look at rootstocks, which historically haven’t been focused on,” explains Bryant. “If the rootstocks are strong, that helps the rest of the plant.”
The company hopes the patent will help make it easier to grow open-field tomatoes – one of the world’s biggest fresh produce and processing crops – in environments increasingly impacted by climate change.
Open-field tomato producers in California, Chile, Argentina and Egypt, for instance, face numerous environmental challenges such as temperature extremes, water scarcity, and soil salinity. “They are crying out for these kinds of innovations,” Bryant says.
The patent could have a major commercial impact for agriculture companies backing polyploid grafting, he says, especially as the market for drought-resistant and heat-tolerant crops is growing as more farmers seek ways to mitigate climate change’s impact.
But an open question is to what extent polyploid grafting will be a scalable solution for farming in hot climates, or, if other advances might rival its impact.
“Several other research efforts focused on genetic modification, plant breeding, and soil management techniques could offer complementary benefits,” Bryant explains.
“Scientists have been working on creating genetically modified tomatoes more resistant to heat and salinity and developing rootstocks that help plants manage water better.
“However, the resistance to genetic modification leaves the playing field clearer for polyploid grafting, as this is a fully non-GMO process.”
Increasing viability of polyploid plants
He calls Tester’s patent a ‘transformative’ step forward. The technology behind it addresses a key challenge in polyploid grafting – namely the difficulty in reliably producing viable polyploid plants.
“Traditional methods often resulted in low success rates or required labour-intensive procedures. This caused minimal adoption levels of polyploid grafting due to the obvious limitations around viable commercial application,” he says.
“However, Tester’s plant science innovation promises to make the process more efficient and scalable, potentially overcoming previous hurdles.”
The technology significantly reduces the timescale and increases the predictability of integrating resilience traits into crops compared to traditional breeding methods, says Bryant.
While at its early stage, meaning the full commercial impact is hard to predict, commercial trials of hybrid grafted diploid rootstocks have already shown a 20-25% increase in tomato yields over leading alternatives.
Early results suggest that polyploid rootstocks could double yields compared to diploid counterparts.
“It’s still natural breeding selection,” Bryant explains. “That is a longer process, but that is how a lot of the world’s seeds are still bred if they if they are non-GMO. But to have a process that can speed up that otherwise quite lengthy and in-depth process is a is a real game changer for the industry.”
The potential for a fundamental change in farming practices in hot climates depends on how quickly and successfully the technology can be implemented at scale, he adds.
Also, of interest is how this development “reconciles with the broader context of agricultural innovation, as scientists, globally, continue to seek ways to make farming more resilient to the challenges of climate change and feed ever-growing populations”.
