Abstract
BackgroundMaize 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.ResultsOf 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.ConclusionsThe 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.
Highlights
Maize rough dwarf disease (MRDD) is a devastating viral disease that results in considerable yield losses worldwide
Evaluation of heterogeneous inbred families (HIFs) in resistance to MRDD The 50 HIFs developed from a maize hybrid CL1165 were evaluated for their resistance to MRDD in Taian for three years and another two locations (Feicheng and Jining) in 2010
105 Single nucleotide polymorphism (SNP) co-segregated with MRDD resistance
Summary
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. Maize rough dwarf disease (MRDD) is a viral disease that results in substantial yield losses in Europe, East Asia, and South America [1,2,3,4]. Current methods for controlling MRDD include pesticides, shifting the date(s) when seeds are planted (i.e., based on projected insect populations), and improving field management [9]. It is important to develop and deploy resistant hybrids by mapping and cloning genes and quantitative trait loci (QTLs) that confer resistance to MRDD
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