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Open Access Research article

Identification and fine-mapping of a QTL, qMrdd1, that confers recessive resistance to maize rough dwarf disease

Yongfu Tao1, Qingcai Liu1, Honghong Wang2, Yanjun Zhang2, Xinyi Huang1, Baobao Wang1, Jinsheng Lai1, Jianrong Ye1, Baoshen Liu2* and Mingliang Xu1*

Author Affiliations

1 National Maize Improvement Center, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, People’s Republic of China

2 State Key Laboratory of Crop Biology, Shandong Agricultural University, 61 Daizong Street, Shandong 271018, People’s Republic of China

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BMC Plant Biology 2013, 13:145  doi:10.1186/1471-2229-13-145

Published: 30 September 2013

Abstract

Background

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.

Results

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.

Conclusions

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.

Keywords:
Maize; MRDD; QTL; Fine-mapping; Recombinant-derived progeny test