The breeding goal: to be faster than the pathogens
However, resistance breeders at KWS already had an alternative when the Rz1 gene was overcome for the first time: Since about the year 2000, further resistance from wild beets Beta maritima has been gradually crossed into the KWS gene pool. In some markets, this is marketed in combination with Rz1 under the name “RZ2.0” and offers particularly good protection against heavy rhizomania infestation.
“It is important that breeders do not attempt to conjure up an alternative resistance out of a hat until a resistance is already broken, but are prepared for such a situation as early as possible. It can take ten years or longer until a new source of resistance has been crossed into marketable varieties,” said Beyer. Breeders are therefore looking for alternative sources of resistance to protect existing defense sources. All in all, it helps that KWS, which has been family-run for more than 160 years, is financially independent and able to think and act in periods of decades. Therefore, in the next few decades, farmers can expect well-adapted, resistant varieties.
Breeding under time pressure
However, it is often only a matter of time until new resistance is also overcome. Some resistance, such as the Rz1 resistance gene against rhizomania, has held firm for many years and the spread of resistant strains of the virus is very slow. In fungi, which often multiply very fast and strong and produce several generations of offspring per year, the process can also be very fast and often take only a few years. The time factor also plays a significant role in competition with other breeding companies. The faster and more efficient KWS can cross a new resistance, the more farmers can benefit from new, innovative products.
Where can new sources of resistance be found?
For many diseases, there are well-known sources of resistance. In addition, breeders often test wild beets from gene banks looking for new resistance genes. Such a process sometimes takes many years to genetically fix a new resistance and analyze its inheritance. Sometimes resistance genes are found in the classic base material, such as resistance to powdery mildew, beet rust and many other harmful fungi.
Above all, breeding is always teamwork: The interaction of several breeding programs and the combination of different resistances make up the varieties that come onto the market. All of this makes it necessary for KWS experts to always be on the lookout for new trial fields with heavy infestation. The leases for the experimental fields around Pithiviers will probably have to be extended several times.