qMrdd2, a novel quantitative resistance locus for maize rough dwarf disease

Area of Science:

• Plant genetics
• Crop science
• Molecular biology

Background:

• Maize rough dwarf disease (MRDD) significantly impacts maize yield and quality.
• MRDD resistance is a complex trait influenced by multiple quantitative trait loci (QTL) and environmental factors.
• Identifying and cloning MRDD resistance genes is crucial for crop improvement.

Purpose of the Study:

• To identify and fine-map a major quantitative trait locus (QTL) conferring resistance to maize rough dwarf disease (MRDD).
• To delineate the genetic interval of the identified QTL for further gene cloning and functional analysis.

Main Methods:

• Utilized a recombinant inbred line (RIL) population derived from a cross between resistant and susceptible maize inbred lines.
• Employed simple sequence repeat (SSR) markers (D184, D1600, N31, N42) for QTL mapping and fine mapping.
• Conducted a recombinant-derived progeny test to narrow down the QTL region.

Main Results:

• A major QTL, designated qMrdd2, was identified on chromosome 2, conferring resistance to MRDD.
• qMrdd2 was fine-mapped to a 577 kb interval between SSR markers N31 and N42.
• The qMrdd2 locus is incompletely dominant and reduced the MRDD disease severity index by 20.4%.

Conclusions:

• A major QTL (qMrdd2) for MRDD resistance has been successfully identified and refined to a 577 kb region.
• The qMrdd2 locus provides a valuable target for enhancing maize resistance to MRDD.
• This finding supports the application of marker-assisted selection (MAS) for developing improved maize varieties.