National Maize Improvement Center, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, People's Republic of China.
BMC Plant Biol. 2013 Sep 30;13:145. doi: 10.1186/1471-2229-13-145.
Maize rough dwarf disease (MRDD) is a devastating viral disease that results in considerable yield losses worldwide. Three major strains of virus cause MRDD, including maize rough dwarf virus in Europe, Mal de Río Cuarto virus in South America, and rice black-streaked dwarf virus in East Asia. These viral pathogens belong to the genus fijivirus in the family Reoviridae. Resistance against MRDD is a complex trait that involves a number of quantitative trait loci (QTL). The primary approach used to minimize yield losses from these viruses is to breed and deploy resistant maize hybrids.
Of the 50 heterogeneous inbred families (HIFs), 24 showed consistent responses to MRDD across different years and locations, in which 9 were resistant and 15 were susceptible. We performed trait-marker association analysis on the 24 HIFs and found six chromosomal regions which were putatively associated with MRDD resistance. We then conducted QTL analysis and detected a major resistance QTL, qMrdd1, on chromosome 8. By applying recombinant-derived progeny testing to self-pollinated backcrossed families, we fine-mapped the qMrdd1 locus into a 1.2-Mb region flanked by markers M103-4 and M105-3. The qMrdd1 locus acted in a recessive manner to reduce the disease-severity index (DSI) by 24.2-39.3%. The genetic effect of qMrdd1 was validated using another F6 recombinant inbred line (RIL) population in which MRDD resistance was segregating and two genotypes at the qMrdd1 locus differed significantly in DSI values.
The qMrdd1 locus is a major resistance QTL, acting in a recessive manner to increase maize resistance to MRDD. We mapped qMrdd1 to a 1.2-Mb region, which will enable the introgression of qMrdd1-based resistance into elite maize hybrids and reduce MRDD-related crop losses.
玉米粗缩病（MRDD）是一种毁灭性的病毒性疾病，导致全球范围内的产量损失相当大。三种主要的病毒株引起 MRDD，包括欧洲的玉米粗缩病毒、南美洲的 Mal de Río Cuarto 病毒和东亚的水稻黑条矮缩病毒。这些病毒病原体属于呼肠孤病毒科的斐济病毒属。对 MRDD 的抗性是一个复杂的性状，涉及多个数量性状位点（QTL）。减少这些病毒引起的产量损失的主要方法是培育和部署抗性玉米杂交种。
在 50 个异质自交系（HIFs）中，有 24 个在不同年份和地点对 MRDD 表现出一致的反应，其中 9 个是抗性的，15 个是易感的。我们对 24 个 HIFs 进行了性状-标记关联分析，发现了六个染色体区域与 MRDD 抗性假定相关。然后我们进行了 QTL 分析，在第 8 号染色体上检测到一个主要的抗性 QTL，qMrdd1。通过对自交回交系进行重组衍生后代测试，我们将 qMrdd1 基因座精细定位到一个由标记 M103-4 和 M105-3 侧翼的 1.2-Mb 区域。qMrdd1 基因座以隐性方式作用，将疾病严重度指数（DSI）降低 24.2-39.3%。使用另一个 F6 重组自交系（RIL）群体验证了 qMrdd1 的遗传效应，该群体中 MRDD 抗性是分离的，qMrdd1 基因座的两种基因型在 DSI 值上差异显著。
qMrdd1 基因座是一个主要的抗性 QTL，以隐性方式作用，增加了玉米对 MRDD 的抗性。我们将 qMrdd1 定位到一个 1.2-Mb 区域，这将使基于 qMrdd1 的抗性基因能够导入到优秀的玉米杂交种中，并减少与 MRDD 相关的作物损失。
