A Review on crop improvement through marker-assisted recurrent backcrossing

Guoyou YE1, Kevin F Smith2

1Bundoora Centre, Biosciences Division, Department of Primary Industries Victoria, and Molecular Plant Breeding Cooperative Research Centre, 1 Park Drive, Bundoora Vic 3086, Australia

2Hamilton Centre, Biosciences Division, The Department of Primary Industries, Mount Napier Road, Hamilton, Vic 3300, Australia

Received: 12 September 2016                          Revised Accepted: 17 November 2016

ABSTRACT

The combined use of marker-assisted selection (MAS) and recurrent backcrossing is a versatile method of   plant breeding and is known as marker-assisted recurrent backcrossing (MARB). Markers are used during recurrent backcrossing to select for the presence of target gene (foreground selection), to select against donor genome contribution (background selection) and to reduce the introgressed segment size and thus linkage drag. MARB reduces the number of backcrossing for recurrent recovery by 3-4 generations if one or two genes are transferred. For foreground selection markers are most useful for traits that are expensive and/or difficult to measure. Linkage drag when present is difficult if not impossible to remove by phenotypic selection. The benefits of MARB were well demonstrated by theoretical and simulation studies, and confirmed by empirical applications. MARB has also been used in generating genetic materials for genetic studies of complex traits. Introgression lines (ILs) have many advantages for QTL mapping compared to other population types such as recombinant inbred lines (RILs) and double haploids (DH). Near isogenic lines (NILs) are commonly used in further study of identified quantitative trait loci (QTL). MARB also offers the possibility of fine mapping QTL by breaking down the QTL-containing segment into smaller pieces.

Key Words: Background selection, Breeding, Foreground selection, Linkage drag, Marker assisted selection, Recurrent backcrossing