The New Zealand Institute for Plant & Food Research Limited, PO Box 4704, Christchurch, New Zealand.
The New Zealand Institute for Plant & Food Research Limited, 120 Mt Albert Rd., Auckland, New Zealand.
Theor Appl Genet. 2016 May;129(5):879-96. doi: 10.1007/s00122-016-2669-3. Epub 2016 Jan 22.
Advances have been made in our understanding of Ascochyta blight resistance genetics through mapping candidate genes associated with QTL regions and demonstrating the importance of epistatic interactions in determining resistance. Ascochyta blight disease of pea (Pisum sativum L.) is economically significant with worldwide distribution. The causal pathogens are Didymella pinodes, Phoma medicaginis var pinodella and, in South Australia, P. koolunga. This study aimed to identify candidate genes that map to quantitative trait loci (QTL) for Ascochyta blight field disease resistance and to explore the role of epistatic interactions. Candidate genes associated with QTL were identified beginning with 101 defence-related genes from the published literature. Synteny between pea and Medicago truncatula was used to narrow down the candidates for mapping. Fourteen pea candidate sequences were mapped in two QTL mapping populations, A26 × Rovar and A88 × Rovar. QTL peaks, or the intervals containing QTL peaks, for the Asc2.1, Asc4.2, Asc4.3 and Asc7.1 QTL were defined by four of these candidate genes, while another three candidate genes occurred within 1.0 LOD confidence intervals. Epistasis involving QTL × background marker and background marker × background marker interactions contributed to the disease response phenotypes observed in the two mapping populations. For each population, five pairwise interactions exceeded the 5% false discovery rate threshold. Two candidate genes were involved in significant pairwise interactions. Markers in three genomic regions were involved in two or more epistatic interactions. Therefore, this study has identified pea defence-related sequences that are candidates for resistance determination, and that may be useful for marker-assisted selection. The demonstration of epistasis informs breeders that the architecture of this complex quantitative resistance includes epistatic interactions with non-additive effects.
我们在了解豌豆壳二孢叶斑病抗性遗传方面取得了进展，通过对与 QTL 区域相关的候选基因进行定位，并证明了上位性互作对确定抗性的重要性。豌豆壳二孢叶斑病（Pisum sativum L.）在全世界范围内分布广泛，对经济有重大影响。病原菌为豌豆壳二孢（Didymella pinodes）、菜豆壳球孢菌（Phoma medicaginis var pinodella）和南澳大利亚的 P. koolunga。本研究旨在鉴定与豌豆壳二孢叶斑病田间抗性相关的 QTL 候选基因，并探索上位性互作的作用。从已发表的文献中确定了 101 个与防御相关的基因，开始鉴定与 QTL 相关的候选基因。利用豌豆和蒺藜苜蓿之间的同线性，缩小了候选基因的作图范围。将 14 个豌豆候选序列映射到两个 QTL 作图群体 A26×Rovar 和 A88×Rovar 中。Asc2.1、Asc4.2、Asc4.3 和 Asc7.1 QTL 的 QTL 峰或包含 QTL 峰的区间，由其中的 4 个候选基因定义，而另外 3 个候选基因则位于 1.0 LOD 置信区间内。QTL×背景标记和背景标记×背景标记互作对两个作图群体中观察到的疾病反应表型有贡献。对于每个群体，有五个成对互作超过 5%的错误发现率阈值。两个候选基因参与了显著的成对互作。三个基因组区域中的标记参与了两个或更多的上位性互作。因此，本研究鉴定了与豌豆防御相关的候选基因，这些基因可能对标记辅助选择有用。上位性的证明告知了育种者，这种复杂的数量抗性的结构包括非加性效应的上位性互作。
