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24 I EUROPEAN SEED I EUROPEAN-SEED.COM t has been recited many times before our planet is faced with some of the most fearsome challenges it has ever seen. We need to produce more food and more energy for an ever-growing population and we need to do that on less land with less water less resources and in a more sustainable manner. And all of that in a changing climate. Over the past century plant breeding has been a major contributor improving plant varieties to cope with population growth. However due to urbanization agriculture has been pushed to ever more marginal lands and yield increases have been plateauing in sev- eral crops. So plant breeders will need to step up their efforts. Continuing on the way they have done so far wont suffice in the coming decades. We need another revolution. And this revolution may very well come in the form of new breeding techniques NBTs. This group of techniques has been devel- oped over the past 10 to 15 years both in the public as well as in the private sector. The beauty of these techniques is they are capa- ble of delivering a desired genetic traits in a much more precise way than other techniques could so far. Whereas in current plant breed- ing there are sometimes limitations in deliv- ering the right characteristics to the target varieties these techniques offer new possibil- ities to EU plant breeders. It is a known fact that conventional plant breeding takes time. Surveys among plant breeding companies show it can take on average from seven to 12 sometimes up to 20 years to generate a new plant variety with the desired characteristics depending on the crop. Use of NBTs significantly shortens this period. For example in certain species it can be very time consuming to introduce a new resistance gene from the same or related species due to the crops complex genetics. The result is not all crosses produce fertile offspring. In addition the growth habit of the crop itself can prevent a quick introduction of By Marcel Bruins the trait. For example trees take several years until the first flowers and fruits develop and it can take decades to create a new variety. In this article well provide a technical overview of the different methods developed so far. A future issue of European Seed will address the regulatory environment surrounding NBTs. SEQUENCE-SPECIFIC NUCLEASE TECHNOLOGY Sequence-specific nuclease SSN technology is often referred to as site-directed nuclease. It uses natural enzymes that generate a dou- ble-strand break in the DNA. These enzymes are linked to man-made structures designed to bind to a specific target DNA sequence. The complex causes a break at an exact pre-de- fined location in the DNA. The plants own repair mechanism repairs the break but often inaccurately. There are three applica- tion types of SSN SSN-1 SSN-2 and SSN-3. With the application type SSN-1 no donor-DNA is used to guide the repair. Non-homologous end-joining NHEJ takes place resulting in most instances in small deletions in the DNA however sometimes small additions can take place. These small alterations lead to loss of gene function a gene knock-out. The SSN-2 technique uses a donor DNA which is a copy of the target DNA region with a small modification. During repair the plant will use this template for the repair and the FIGURE 1. Outline of sequence-specific nuclease technologies SSN-1 SSN-2 and SSN-3. NEW BREEDING TECHNIQUES PROMISING TECHNIQUES TO ACCELERATE INNOVATION IN PLANT BREEDING. IllustrationcourtesyofWageningenUR