Breeding 22 December 2016

Are hybrid
potato seeds
the future?

Hybrid potatoes are piquing the interests of people both within and outside the potato sector. A hybrid combines the best of two systems in order to maximize performance. In the same way that a hybrid car achieves maximum horsepower by using the electric and the diesel engine, two specially developed parent lines create a strong and high-performance variety when crossed. Successful hybridization can significantly boost potato breeding. It can also replace seed potatoes with actual seeds. In other words: it's possible to grow potatoes from seeds instead of seed material (seed potatoes). But what does hybridization mean? And will it change the sector for good?

The history of potato breeding

'The market still uses hundred-year-old potato varieties. Unlike other crops, their potential cannot be structurally improved each year, although bigger strides have been made over the past fifteen years,' explains Robert Graveland, R&D manager at HZPC. 'Breeding is about controlling the properties and speed of genetic reorganization. You can compare classic breeding to having two crystal glasses which you smash and then put together in a new form. It's never going to be perfect. You start all over again with each new hybrid.'

There are two types of propagating material. Most varieties are cultivated from seed potatoes. This means each tuber is a clone of another tuber, which makes them genetically identical. A small portion is available as seed, which is known as a true potato seed (TPS) variety. This is a genetic mixture of seeds that looks relatively uniform at the plant and tuber level. What's new is how we create true hybrids, which combines the ideal elements of both systems.

“This is an entirely new approach that offers new opportunities”
Robert Graveland
Robert Graveland

Hybrid breeding

'Hybridization means you create inbred strains that are used as the parents during the cross breeding stage,' explains Robert. 'The seeds from this hybrid constitute the variety. In current breeding practices, each individual seed is different and the cloned tubers from a single original seed constitute the variety. With hybrid breeding, the seeds are identical and form the propagating material for a variety. The emphasis is on creating the right parent combinations and seed quality, instead of making a lot of individual clones and tuber progenies. Creating parent lines for potatoes is a problem, as is the self-pollination required for producing these parent lines. Now that this has become technologically feasible, hybrid potatoes from seeds are attracting attention both within and outside our sector. Instead of using the tuber as the basis, we can now use the seed. This is an entirely new approach that offers new opportunities. More importantly, it's a common breeding practice used for a variety of crops, including tomatoes, sweetcorn, and sugar beets. It has nothing to do with genetic manipulation.'

More about the new potato breeding technique
Hybridization as a new potato breeding technique

The problem with potato breeding is that it takes a long time for the new variety to develop the desired properties. This is because potatoes have four sets of different chromosomes (tetraploid). A cross between two different potatoes can yield an almost infinite number of different offspring. Adjusting an existing variety is impossible. Your only other option is to adopt new breeding techniques, but these are still pending government authorization.

With conventional potato breeding, it's difficult to add an important quality from a wild potato variety, such as disease resistance, to a new variety. That would require you to transplant and research a lot of offspring in order to find a handful of useable plants with the desired properties. It could take up to twenty years before you could market a clone with this new property. Using DNA markers has certainly improved this process.

This process was solved for several other crops by creating inbred lines with identical chromosomes that were used as parents in crosses. This is known as hybrid breeding and was not possible with potatoes until now because diploid potato plants cannot self-propagate. Additionally, potatoes resulted in poor plants more than other crops during the inbreeding process. Having found a way to create suitable parent lines has opened up new possibilities for potato breeding.

A bag of seed is
cheaper to transport
than a container
of seed potatoes

Are hybrid potatoes the future?

With the help of parent lines, newer and stronger varieties can be developed more quickly, and existing varieties can be improved. Moreover, the hybrid varieties can be traded as seeds instead of seed potatoes. A bag of seed is cheaper to transport than a container of seed potatoes. More importantly, the risk of diseases is much lower in seeds than seed potatoes. The Erwinia bacteria, one of the biggest problems when cultivating seed potatoes, is not transferred to the plants when cultivated from seeds, giving the plants a healthy start.

'All the elements for success are present,' says Robert. 'Technically speaking, it's possible but there are still a lot of questions that need answering. We are now trying to figure out whether we can achieve the right mass and therefore the right yield. If so, the next question is whether it will be successful on the market. Hybrid varieties need to have a clear added value compared to existing varieties. Another question is whether the existing cultivation systems are adequate enough. People are used to cultivating tubers, not seeds. I think it will take at least ten years to verify the technical aspects.'

Seed versus tuber

'I believe that seeds and tubers will always complement each other,' Robert stresses. 'Seeds have their advantages, but so do tubers. Tubers have more vigorous growth, particularly in the beginning of the season. This is important when growing potatoes in a colder climate or in an area with poor irrigation.' The more common potato cultivation becomes, the more revolutionary this will be for cultivation practices!

HZPC & hybrid potatoes

Plant breeding is both an ancient practice and a very current one when it comes to the availability of safer and higher-quality food to feed the world's growing population. Hybrid breeding allows us to breed higher quality potato varieties more quickly, using fewer pesticides. Cultivating hybrid potatoes from seeds could make an important contribution to solving the global food problem. HZPC is always looking for new developments in this sector and views many of the elements of hybridization as having a good potential for success. Methods to accelerate the breeding process and make it more effective are always of interest to HZPC.

Read more on Breeding

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