BARLEY-NAM: Locating exotic genes that control agronomic traits under stress in a wild barley nested association mapping (NAM) population

面对气候变化，实现可持续的粮食生产需要在作物育种方面进行一场革命，以便在波动的不利环境条件下实现高产和可持续的产量。现代作物的祖先野生种质含有可以实现这一目标的等位基因变体，但现代作物的生物多样性正日益枯竭。成功利用野生种质的两个关键障碍是找到所需的野生等位基因并在田间进行测试。spontaneum）作为模式，并应用新的基因组和育种工具来改善优良大麦在非生物和生物胁迫下的农艺表现。为此，我们将使用第一个谷物NAM群体HEB-25应用嵌套关联映射（NAM）方法。HEB-25包含1，420个BC 1 S3系，细分为25个家族，源自优良大麦栽培品种Barke与25种不同野生大麦供体的杂交。HEB-25系将首先评估21，643个基因（每个已知的高置信度大麦基因）的等位基因含量，采用最先进的外显子组捕获和下一代测序。我们预计将在HEB-25中绘制大约40万个SNP，为大麦提供前所未有的基因和基因组分辨率。第二，所有HEB品系将在德国、苏格兰和以色列进行田间试验，以评估在缺氮、干旱和病原体攻击下的农艺表现。将对产量构成因素和营养成分以及对主要大麦疾病叶锈病、黄锈病和网斑病的抗性进行评分。此外，将通过非侵入性遥感技术建立农艺表现模型，以建立表型预测。第三，收集的数据集将在一个中央数据仓库中存档和进一步处理，该仓库是围绕一个可上网查阅的定制关系数据库建立的。第四，HEB-25的基因型和表型数据将在全基因组关联扫描（GWAS）中组合，以鉴定在胁迫下改善植物性能的野生大麦等位基因。由于基因分辨率极高，因此本研究将产生单独的高置信度候选基因，这些候选基因可调节所研究的性状。第五，为了验证所鉴定的性状改良外来等位基因，将从HEB系开发分离的高分辨率后代。BARLEY-NAM项目将在两个方面受益。一方面，调节大麦农艺性状的基因和基因变体将以前所未有的作物细节水平进行定义，这将为小麦和黑麦的平行改良提供未来策略。另一方面，野生大麦的性状改良等位基因将在未来的大麦育种中得到应用。这将导致新的大麦品种具有更好的性能，并扩大了优良大麦基因库的生物多样性和可持续性。

Delivering sustainable food production in the face of climate change requires a revolution in breeding crops that deliver high and sustainable yield under fluctuating disadvantageous environmental conditions. The ancestral wild germplasm of modern crops contains allelic variants that can achieve this goal, yet modern crops are becoming increasingly depleted in biodiversity. The two key obstacles to successful exploitation of wild germplasm are finding the wild-derived alleles needed and testing them in the field.The BARLEY-NAM project will use wild barley (Hordeum vulgare ssp. spontaneum) as a model and apply novel genomic and breeding tools to improve agronomic performance of elite barley under abiotic and biotic stresses. For this, we will apply the nested association mapping (NAM) approach using the first cereal NAM population, HEB-25. HEB-25 comprises 1,420 BC1S3 lines, sub-divided into 25 families, originating from crosses of the elite barley cultivar Barke with 25 different wild barley donors. The HEB-25 lines will first be assessed for allele content at 21,643 genes (every known high-confidence barley gene), employing state-of-the-art exome capture and next generation sequencing. We expect to map roughly 400,000 SNPs within HEB-25 giving unprecedented levels of gene and genome resolution for barley. Second, all HEB lines will be cultivated in field trials in Germany, Scotland and Israel to assess agronomic performance under nitrogen deficiency, drought and pathogen attack. Yield components and nutrient content will be scored, as well as resistance against the major barley diseases leaf rust, yellow rust and net blotch. In addition, agronomic performance will be modelled by non-invasive remote sensing technology to establish phenotype predictions. Third, the collected data sets will be archived and further processed in a central data warehouse, built around a custom web-accessible relational database. Fourth, genotype and phenotype data of HEB-25 will be combined in a genome-wide association scan (GWAS) to identify wild barley alleles that improve plant performance under stress. Since the gene resolution is extremely high, this study will yield individual high confidence candidate genes that putatively regulate the studied traits. Fifth, to validate the identified trait-improving exotic alleles, segregating high-resolution progeny will be developed from the HEB lines. The BARLEY-NAM project will be beneficial in two directions. On the one hand, the genes and gene variants regulating agronomic traits in barley will be defined at a level of detail unprecedented for the crop and this will inform future strategies for parallel improvement in wheat and rye. On the other hand, trait-improving wild barley alleles will be available for application in future barley breeding. This will lead to new barley cultivars with improved performance and extend the biodiversity and sustainability of the elite barley gene pool.