New UK potato varieties with late blight and potato cyst nematode resistance, reduced bruising and improved processing quality

土豆是英国和世界上极为重要的作物，在世界粮食安全中起着关键作用。然而，由于现有品种的若干缺陷，产量以及加工和消费的适宜性大大降低。对许多病虫害的易感性是主要问题，特别是由疫霉引起的晚疫病（爱尔兰马铃薯饥荒的原因）和马铃薯囊肿线虫引起的根系损害。在凉爽的条件下储存土豆会增加还原糖（冷诱导的甜味）的含量，导致（在氨基酸天冬酰胺含量较高的情况下）在油炸或烘烤后产生可能对健康有害的丙烯酰胺。土豆在碰伤后也容易变黑，造成相当大的浪费，增加了消费者的成本。植物抗病基因的功能是检测病原体分子，然后激活防御机制。尽管马铃薯携带了上百种抗性基因，但栽培品种缺乏能够检测和战胜晚疫病（LB）有机体的基因。幸运的是，一些野生马铃薯品种表现出对LB的抗性，我们已经从这些近缘种中追踪并分离出LB抗性基因。然后可以用转基因方法将这些基因引入马铃薯，从而产生具有有效抗性的品种。为了确保这种抗性持久，在这个项目中，我们的目标是结合三种不同的LB抗性基因，使LB病原体更难以绕过这种保护。当土豆在凉爽的环境中储存时，它们会积累大量的还原糖，如葡萄糖，以及大量的天冬酰胺。在油炸过程中，它们会转化为一种叫做丙烯酰胺的有毒分子。通过抑制块茎中的两种植物基因（转化酶和天冬酰胺合成酶），美国公司Simplot降低了块茎中的葡萄糖和天冬酰胺水平，从而降低了丙烯酰胺的含量，减少了油炸后的发黑现象。瘀伤后的褐变是由酶（PPO）与细胞酚类化合物的相互作用引起的。同样，通过沉默，Simplot在块茎中实现了较低的PPO水平，并降低了块茎对瘀伤的易感性。在美国，Simplot正处于将这些低丙烯酰胺和瘀伤控制基因（LABC）性状的马铃薯品种商业化的后期阶段。美国利兹大学的研究人员对马铃薯进行了基因改造，使其根部能够表达抑制PCN的蛋白质。一种是干扰PCN神经系统的小肽。另一种是线虫用来在植物根部定植的蛋白酶抑制剂。结合起来，这些蛋白质可以大大减少线虫的损失，即使在严重感染的土地上也是如此。在这个项目中，我们的目标是将这些特性结合到流行的马铃薯品种Maris Piper和Agria中。我们将在一个T-DNA上设计三个LB抗性基因，连接到一个植物基因选择标记进行转化，并在田间测试效果。我们还将LB抗性基因与LABC抗性基因组合在一起进行田间试验，最后将LB抗性和LABC抗性与PCN抗性基因组合在一起进行田间试验。通过与Simplot的合作，我们将为每个构建体生产至少100株植物，并筛选携带简单DNA插入的细胞系，以及所传递的所有基因的功能。目标是选择适合随后商业化的植物品系。在这些实验中，我们还将生成非常有用的信息，了解多个基因（在我们的案例中，多达9个基因）在一次事件中传递的效率，并且仍然具有所有功能。这一信息将对其他打算通过转基因方法在其他作物中同时传递多种有用基因的人有用。

Potatoes are an extremely important UK and world crop with a key role in world food security. However yields, and suitability for processing and consumption, are much reduced by several shortcomings in currently available varieties. Susceptibility to many diseases and pests, particularly late blight caused by Phytophthora infestans (cause of the Irish potato famine) and root damage caused by potato cyst nematodes, are major problems. Storing potatoes in cool conditions elevates levels of reducing sugars (cold-induced sweetening), resulting (in lines with high levels of the amino acid asparagine) in potentially health-damaging acrylamide production after frying or roasting. Potatoes are also susceptible to blackening upon bruising, resulting in considerable waste, raising costs to consumers. Plant disease resistance genes function by detecting molecules from a pathogen and then activating defence mechanisms. Although potatoes carry 100s of resistance genes, cultivated varieties lack those enabling it to detect and defeat the late blight (LB) organism. Fortunately, some wild species of potato show resistance to LB, and we have tracked down and isolated LB resistance genes from some of these relatives. Such genes can then be introduced into potato using GM methods, resulting in varieties with effective resistance. To ensure this resistance is long lasting, in this project we aim to combine three different LB resistance genes, to make it more difficult for the LB pathogen to by-pass this protection. When potatoes are stored in cool conditions, they can accumulate high levels of reducing sugars such as glucose, and also high levels of asparagine. During frying, these are converted to a toxic molecule called acrylamide. By silencing two plant genes (invertase and asparagine synthetase) specifically in tubers, the American company Simplot has reduced levels of glucose and asparagine in tubers, resulting in lower acrylamide and less blackening upon frying. The browning that results upon bruising is caused by the interaction of an enzyme (PPO) with cellular phenolic compounds. Again, using silencing, Simplot have achieved lower PPO levels specifically in tubers and reduced susceptibility of tubers to bruising damage. Simplot are in advanced stages of commercialising potato varieties with these low acrylamide and bruise control genes (LABC) traits in the US.Researchers in U. Leeds have engineered potatoes with roots that express proteins that inhibit PCN. One is a small peptide that interferes with the PCN nervous system. The other is an inhibitor of a protease used by the nematode to colonize the plant root. In combination, these proteins can greatly reduce losses to nematodes even on heavily infested land.In this project we aim to combine these traits in the popular potato varieties Maris Piper and Agria. We will engineer the three genes for LB resistance on one T-DNA, linked to a plant gene selectable marker for transformation, and test efficacy in the field. We will also combine LB resistance genes with LABC genes and test in the field, and finally we will combine LB resistance and LABC with PCN resistance genes and test in the field. In partnership with Simplot, we will produce at least 100 plants for each construct and screen them for lines that carry simple DNA inserts and for functionality of all the genes that were delivered. The goal is to select plant lines that are suitable for subsequent commercialization. During these experiments, we will also generate very useful information about the efficiency with which multiple genes (in our case, up to 9 genes) can be delivered in one event, and still all function. This information will be useful to others setting out to simultaneously deliver multiple useful genes by GM methods in other crops.