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 a particularly good protection against heavy rizomania 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", says Beyer. Breeders are therefore looking for alternative sources of resistance to protect the existing defence 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 rizomania, 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 the 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 analyse 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 programmes 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 be always 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.