Potato PCN Resistance: Cloning effective resistances against potato cyst nematodes

马铃薯是世界上最重要的非谷类粮食作物，其生产受到病原体的威胁，这些病原体严重降低了作物产量和质量，并阻碍了种薯的生产。马铃薯囊肿线虫（PCN）是马铃薯广泛分布的病原体，一旦建立就很难根除。马铃薯产业依赖于获得无PCN的土地来生产健康的种块茎，以及抗PCN的马铃薯品种，以抑制这种具有经济破坏性的害虫的种群。目前防治PCN的方法往往依赖于对环境有害的杀线虫剂，因此在许多马铃薯生产国逐渐被淘汰。此外，在英国，作物轮作通常持续6到7年，可以帮助减少疾病压力，但不能清理受污染的土地，因为土壤中的PCN囊肿可以存活20多年。人们认识到，通过引入野生物种的抗病基因，可以保护栽培马铃薯免受PCN等病原体的侵害，这导致将对PCN物种Globodera rostochiensis有效的H1抗性以及对G. pallida有效的Gpa5和Gpa4抗性部署到栽培品种中。先前对这些抗性的遗传作图研究已经提供了证据，表明迄今为止难以捉摸的基因可能是植物核苷酸结合、亮氨酸富重复基因家族（NLRs）的成员。该项目旨在确定对这两种线虫产生抗性的功能性nlr，并了解这些基因在识别病原体分子（称为效应物）时提供保护的分子机制。正是这种关于宿主和病原体分子的综合知识决定了马铃薯被感染或自我防御的能力，育种者需要为未来开发出具有抗性的马铃薯品种。我们的联盟汇集了来自詹姆斯·赫顿研究所和塞恩斯伯里实验室的马铃薯nlr专家，以及詹姆斯·赫顿研究所和剑桥大学的PCN专家。我们得到了国际公司百事可乐Solynta和Averis的支持，以及2Blades基金会的支持，以确保研究的即时影响。这个项目的关键资源已经到位。对于马铃薯，这包括我们使用由该联盟成员共同开发的RenSeq技术优先重新排序nlr的能力。使用RenSeq，我们已经能够表示含有H1、Gpa5和Gpa4基因的现有马铃薯品种的nlr。这使得强大的关联研究能够识别候选基因。利用现有的高通量转化能力，可以快速评估这些候选nlr，以鉴定功能性线虫抗性基因。对于PCN，我们有适当的基因组资源，如PCN两种物种的基因组组装和建立管道，以确定可能的候选效应基因。此外，我们已经选择了G. rostochiensis和G. pallida的PCN群体，分别对携带H1， Gpa5或Gpa4的马铃薯植株具有毒力。这些种群将使我们能够在检测时优先考虑触发马铃薯抗性反应的候选无毒基因。通过Solynta和Averis，我们可以接触到能够逃避Gpa5抗性的PCN种群，并使我们能够研究毒性。这些资源的结合使项目非常及时和可行。该项目产生的知识将a)解决我们对植物寄生线虫抗性理解的科学空白，b)将为保护马铃薯生产提供应用成果。事实上，我们期望达到这样一个位置，即我们可以告知育种者可以组合的抗性的性质，并通过考虑病原体效应物的多样性（包括真正无毒基因的变化）来预测它们的有效性。

Potato is the world's most important non-cereal food crop and production is threatened by pathogens that severely reduce crop yield, quality, and impede seed potato production. Potato Cyst Nematodes (PCN) are widespread pathogens of potato that are difficult to eradicate once established. The potato industry is dependent on access to PCN-free land to produce healthy seed tubers as well as PCN resistant potato varieties to suppress populations of this economically damaging pest.Current control methods for PCN often depend on nematicides which can be environmentally damaging and are consequently being phased out in many potato producing countries. Further, crop rotations, which in the UK typically span between six to seven years, can help reduce the disease pressure, but fail to clean-up contaminated land as PCN cysts in the soil can remain viable for over 20 years. The realisation that cultivated potatoes can be protected from pathogens such as PCN by the introduction of disease resistance genes from wild species led to the deployment into cultivars of the H1 resistance effective against the PCN species Globodera rostochiensis and Gpa5 and Gpa4 that are effective against G. pallida. Previous genetic mapping studies of these resistances have provided evidence that the hitherto elusive genes are likely members of the plant nucleotide-binding, leucine-rich-repeat gene family (NLRs). This project aims to identify the functional NLRs that are responsible for the resistances against both nematode species and to understand the molecular mechanism by which these genes provide protection upon recognition of pathogen molecules known as effectors. It is this combined knowledge about the host and pathogen molecules that determine the ability of potatoes to be infected or to defend themselves that breeders require to develop resistant potato varieties for the future. Our consortium brings together experts on potato NLRs from The James Hutton Institute and The Sainsbury Laboratory alongside PCN experts from The James Hutton Institute and the University of Cambridge. We have obtained support from the international companies PepsiCo Solynta and Averis, as well as the 2Blades foundation to ensure immediate impact of the research. Key resources for this project are already in place. For potatoes, this includes our ability to preferentially re-sequence NLRs using a technology known as RenSeq that was jointly developed by members of this consortium. Using RenSeq, we have been able to represent the NLRs in existing potato varieties that contain the genes H1, Gpa5 and Gpa4. This enables powerful association studies to identify gene candidates. By taking advantage of existing high-throughput transformation capabilities, these candidate NLRs can be assessed quickly to identify the functional nematode resistance genes. For PCN, we have in place genomic resources such as genome assemblies of both PCN species and established pipelines to identify likely candidate effector genes. In addition, we have PCN populations of G. rostochiensis and G. pallida that have been selected for virulence on potato plants carrying H1, Gpa5 or Gpa4, respectively. These populations will allow us to prioritise candidate avirulence genes that trigger the potato resistance responses upon detection. Through Solynta and Averis we have access to PCN populations that can evade Gpa5 resistance and allow us to study virulence.These resources combined make the project extremely timely and feasible. The knowledge generated in this project will a) address a scientific gap in our understanding of resistances against plant-parasitic nematodes and b) will deliver an applied outcome to protect potato production. Indeed, we anticipate reaching a position where we can inform breeders about the nature of resistances that can be combined and predict their effectiveness by considering pathogen effector diversity including changes to bona fide avirulence genes.