Breeding potatoes is notoriously difficult. First, commercial potato cultivars don’t self-pollinate, which has historically prevented breeders from creating stable, genetically pure inbred lines needed for hybrid breeding.
Second, most commercial varieties are tetraploids, with four sets of chromosomes that make inheritance unpredictable. Third, they are highly heterozygous, with extensive genetic variation, such that desired traits can be lost or diluted in crosses.
Finally, while potatoes have berries that contain seeds, growers typically propagate potatoes clonally by planting tubers (small pieces of potato) because the seeds produce highly variable offspring with mixed traits.
Clonal propagation ensures genetic consistency but in turn preserves disease (as every new plant is a genetic clone) and limits genetic refresh as there is no genetic recombination to introduce new traits, says Charles Miller, director of strategic alliances and development at Dutch biotech firm Solynta.
“Think of it like a photocopy,” he says. “Each time you make a copy, the quality gets less.”
Put simply, observes Miller, all this makes potato breeding a crapshoot.
Solynta, however, has pioneered tech allowing potatoes to self-pollinate and produce non-GMO true seeds in a controlled way, turning a game of chance into something far more predictable, he says. It also means growers can kiss goodbye to saving, storing, and planting tubers for next season’s crop.
AgFunderNews (AFN) caught up with Miller (CM) after Solynta secured €20 million ($23 million) in venture debt financing from the European Investment Bank (EIB) to discuss why hybrid breeding is a gamechanger for potatoes and what’s next for the company.
AFN: What peculiar challenges are involved with potato breeding?
CM: Potatoes are tetraploids, so they have four sets of chromosomes, and if you want to make a cross it’s incredibly complex to figure out what’s actually going to happen. To get a potato out of a cross which contains, say, nine traits you might want to have, you would have to plant several plots of land the size of planet Earth to get one tuber that you’re looking for.
That’s extremely inefficient, which is why we have potato varieties that have been in cultivation for over 100 years. In the West Coast of the US, for example, one of the most popular is the Russet Burbank, and most likely it’s over 150 years old.
There have been agronomic practices that make us better at producing potatoes, but really, there’s been no targeted improvement. So if for example there is a blight or fungus that all of a sudden comes in from another part of the world, it would take decades just to find the right potato, and then it would take another decade to make additional photocopies, which is what you effectively get when you propagate clonally. With a photocopy, each time you make a copy, the quality gets less.
AFN: So Solynta has isolated a gene which allows a potato plant to self-pollinate, or fertilize itself with pollen from the same plant?
CM: Yes, we isolated this Sli gene from a wild variety. It’s basically the same type of gene that you see in other hybrids that enables self-compatibility [so Solynta can create inbred parent lines that have been self-pollinated over many generations until they become genetically uniform].
By being able to create uniform Non-GMO parents, we are able to isolate genetic traits that are beneficial for growers and for consumers and start using traditional and modern techniques such as molecular breeding or AI-focused crosses, so we can become significantly more efficient.
AFN: What are some of the practical problems of growing potatoes from tubers?
CM: If you’re in a developed part of the world, you plant in May and harvest in October, more or less. And then from October until April you store your tubers for next year in massive climate-controlled warehouses which are very expensive and have a large environmental footprint. And then you’re trucking two and a half tons per hectare of tubers all over the place.
If you’re in Kenya, for example, you can have two seasons a year, and there’s about a month and a half to two months between the seasons. So you need a potato that doesn’t store very long before it starts to sprout. So you can’t take a russet tuber which has a long dormancy [before it sprouts] and just transfer it from the US to Kenya, and expect that it’s going to work. Also in many parts of the world, they simply don’t have the infrastructure to store tubers.
And that’s one of the real benefits of true seeds. What’s in my coffee cup here would probably be enough to plant 15 or 20 hectares. Using seeds might mean, say, one month longer growing time relative to a tuber, but you have everything ready when you want it, or when the weather allows it.
AFN: Stepping back, what’s the significant of hybrid breeding and true seeds for potatoes?
CM: It’s revolutionary. You wouldn’t see so many other companies working in this space if that wasn’t generally accepted. Potatoes have largely managed to survive with clonal propagation [via tubers], but it comes with a lot of problems. As the climate changes, we need to move much more quickly.
I think the potato industry has realized that and to a large degree has embraced this concept of hybrid breeding. But like a lot of revolutions it takes time to simmer and develop.
AFN: Where are you finding potato varieties with desirable traits?
CM: Whether you’re a traditional potato breeding company, or whether you’re us or Ohalo, you have a genetic library from wild sources and public sources. We can also work with collaborators who have their own gene pool.
We have also mapped the genome of diploid potatoes [which have two copies of each chromosome, rather than four], so we know pretty well what genes do what. That allows us to go through other diploids, perhaps a wild species or something that has an interesting trait, take blight resistance for example, and compare it against the map.
And then we can, with a high degree of certainty, know if, in fact, those genes exist [if the wild potato’s DNA carries the genes that confer resistance to the blight]. If they do, we can isolate them and start the backcrossing process.
AFN: How competitive is the potato hybrid breeding field?
CM: There are several other companies and quite a few public institutions working on hybrid breeding, including Aardevo and Ohalo, then you have one of the largest seed tuber companies in the world, HZPC. Several Chinese institutes are also doing it, and the University of Wisconsin.
However, we were the first company to actually isolate those genes [that confer self-compatibility] and we are also the first company that is making hybrids commercially available. So we’re doing that in Europe, we’re doing that in several countries in Africa, and we have plans to do that in a lot of other countries. Solynta is leading the curve at the moment, although of course that can change as it’s a competitive environment.
AFN: What is Solynta’s business model?
CM: We sell true botanical seeds largely to seed distribution companies [with 25g of seed farmers can plant the same area that otherwise requires 2,500kg of tubers]. From time to time we also sell them direct to larger growers.
AFN: Why the initial focus on Africa?
CM: We saw a product market fit. The products that we’re releasing in that part of the world have multiple genes of late blight resistance built into them. That’s a huge problem in that part of the world and a lot of growers there have crop failures or extremely limited yields because of late blight that they can’t control. We offer a unique benefit that’s not currently available in the market.
When we first started trials in Kenya about four and a half years ago, we were yielding 10-15% below the local checks. Over that period of time, we’ve been able to not only meet, but on average, exceed local checks, and that gives us confidence in the traits that we’re bringing with the new products.
We’ve got three varieties registered on the national list in Kenya and we have two distributors on board starting to commercialize the products: Bayer and ETG.
In many parts of the world, good quality starting material is hard to come by, and that is really where this technology can shine. If you can’t access quality seed tubers, but you can still access high quality seed, you have the opportunity to grow a potato crop which didn’t exist before.
AFN: When do you hope to enter the EU market?
CM: In the EU you’re required to test and show distinctness and uniformity so that you can register your variety. We are now in the second phase of doing that and we expect to have that finalized and several varieties released by the end of this year or early next year.
It’s a very frustrating process and it’s quite slow. One of the reasons is because while potatoes are not new, hybrid potatoes are, and delivering true seeds into the market is new. But now that a pathway has been defined, we expect to have the first varieties coming [to market] soon.
AFN: What about other markets?
CM: We’re also working with several other markets within the tropical highland zone of Africa. So think Uganda, Burundi, Rwanda, Nigeria… In these places we’re in similar stages as we are in Europe, where we expect to have several varieties registered by the end of this year, early next year.
In the US, we’re working on a market access request. We’re working with the American Seed Trade Association and Aardevo and quite a few other groups to allow standardized importation of true potato seeds. The process here is extremely slow, but the USDA and its counterparts in the Netherlands have been working quite well together so we think we’re in the final stages.
AFN: What traits have you been focusing on?
CM: We’ve been really focusing on late blight. It’s the reason that we had the [Irish] potato famine, but it’s also still highly relevant in that growers have to spray [fungicides] about every 10 days, so they are putting a lot of chemicals on the land and causing a lot of soil compaction, plus it’s relatively expensive.
Up to 30% of the potato crop globally is destroyed by late blight, so our newest varieties have a stack of three genes that allow growers to combat several different types of blight during the same season.
We’re also looking at viruses, which are a big deal in potatoes, potato wart disease, and Colorado potato beetles.
AFN: How soon could you go from identifying a trait of interest in a wild potato and coming up with true seeds with that trait?
CM: Let’s say we find some gene that allows French fries to absorb less oil, we isolate that gene and with molecular breeding, we would probably be able to integrate that into some elite parents in the course of two years. Assuming all goes well, you would make a couple of crosses. Then to make a selection of hybrids that might take, let’s say, another 12 months, because you get two seasons a year.
So now you’re looking at three years, and on the fourth year, you would probably have some pilot hybrid production and some testing of your crosses. So five to seven years, let’s say. But if the genes are completely isolated and well known and don’t bring a lot of baggage with them when you transfer them into your elite parents, you could do that a lot faster.
The post Breeding potatoes is a crapshoot; Solynta stacks the deck with hybrid seed tech appeared first on AgFunderNews.