Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 76 Page 77 Page 78 Page 79 Page 80 Page 81 Page 82 Page 83 Page 84 Page 85 Page 86 Page 87 Page 88 Page 89 Page 90 Page 91 Page 92 Page 93 Page 94 Page 95 Page 96 Page 97 Page 98 Page 99 Page 100 Page 101 Page 102 Page 103 Page 104 Page 105 Page 106 Page 107 Page 108 Page 109 Page 110 Page 111 Page 112 Page 113 Page 114 Page 115 Page 116Plant Breeding 70 www.seed.ab.ca | Advancing Seed in Alberta IT 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 several crops. So plant breeders will need to step up their efforts. Continuing on the way they have done so far won’t suffice in the coming decades. We need another revo- lution. And this revolution may very well come in the form of new breeding techniques (NBTs). This group of techniques has been developed 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 capable of delivering a desired genetic trait(s) in a much more precise way than other techniques could, so far. Whereas in current plant breeding there are sometimes limitations in delivering the right characteristics to the target varieties, these techniques offer new possibilities 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 crop’s 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 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, we’ll 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 New Breeding Techniques a double-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-defined location in the DNA. The plant’s own repair mechanism repairs the break, but often inaccurately. There are three application 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). Site-Specific Nuclease (SSN) Technology SSN DSB repair DNA DNA with SSN-induced, double strand break (DSB) Repair of the DSB by the cells' native repair system Non-accurate repair, following non-homologous end-joining (NHEJ) deletion or small modification SSN-1 Accuratehomologous recombination (HR)-directedrepair usingtemplateDNA withsmallchange small modification SSN-2 C C Accurate (HR)-directed repair using template DNA with new insert introductionofnewDNA fragment SSN-3 Promising techniques to accelerate innovation in plant breeding. Figure 1. Outline of sequence-specific nuclease technologies SSN-1, SSN-2 and SSN-3.