Department of Agrobiotechnology, IFA-Tulln, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Str. 20, 3430, Tulln, Austria.
Saatzucht Donau GesmbH & CoKG, Saatzuchtstrasse 11, 2301, Probstdorf, Austria.
Theor Appl Genet. 2023 Mar 23;136(4):79. doi: 10.1007/s00122-023-04312-2.
A novel genomic selection strategy offers the unique opportunity to develop qualitative race-specific resistant varieties that possess high levels of the more durable quantitative race-nonspecific resistance in their genetic background. Race-specific qualitative resistance genes (R-genes) are conferring complete resistance in many pathosystems, but are frequently overcome by new virulent pathogen races. Once the deployed R-genes are overcome, a wide variation of quantitative disease resistance (QDR) can be observed in a set of previously race-specific, i.e., completely resistant genotypes-a phenomenon known as "vertifolia effect." This race-nonspecific QDR is considered to be more durable in the long term, but provides merely a partial protection against pathogens. This simulation study aimed to detangle race-specific R-gene-mediated resistance of pending selection candidates and the QDR in their genetic background by employing different genomic selection strategies. True breeding values that reflected performance data for rust resistance in wheat were simulated, and used in a recurrent genomic selection based on several prediction models and training population designs. Using training populations that were devoid of race-specific R-genes was thereby pivotal for an efficient improvement of QDR in the long term. Marker-assisted preselection for the presence of R-genes followed by a genomic prediction for accumulating the many small to medium effect loci underlying QDR in the genetic background of race-specific resistant genotypes appeared furthermore to be a promising approach to select simultaneously for both types of resistance. The practical application of such a knowledge-driven genomic breeding strategy offers the opportunity to develop varieties with multiple layers of resistance, which have the potential to prevent intolerable crop losses under epidemic situations by displaying a high level of QDR even when race-specific R-genes have been overcome by evolving pathogen populations.
一种新的基因组选择策略提供了一个独特的机会，可以开发出具有高水平更持久的定量非专化抗性的定性专化抗性品种，这些品种在其遗传背景中具有高水平的定量非专化抗性。定性专化抗性基因（R 基因）在许多病原系统中赋予完全抗性，但经常被新的毒力病原菌群体所克服。一旦部署的 R 基因被克服，在一组以前的专化的，即完全抗性的基因型中，可以观察到广泛的定量疾病抗性（QDR）变异——这种现象被称为“vertifolia 效应”。这种非专化的 QDR 被认为在长期内更持久，但只能提供对病原体的部分保护。本模拟研究旨在通过采用不同的基因组选择策略，理清待选品种中定性 R 基因介导的抗性和遗传背景中的 QDR。模拟了反映小麦锈病抗性表现数据的纯合值，并在基于几种预测模型和训练群体设计的反复基因组选择中使用。因此，长期有效地提高 QDR 的关键是使用不包含定性 R 基因的训练群体。随后对 R 基因的存在进行标记辅助预选，然后进行基因组预测，以在定性抗性基因型的遗传背景中积累 QDR 所涉及的许多中小效应位点，这似乎是一种同时选择两种抗性的有前途的方法。这种基于知识的基因组育种策略的实际应用提供了开发具有多层抗性品种的机会，即使由进化病原体种群克服了定性 R 基因，这些品种也具有通过表现出高水平的 QDR 来防止在流行情况下不可容忍的作物损失的潜力。
