Location: Crop Genetics and Breeding ResearchTitle: Marker-assisted selection to pyramid nematode resistance and the high oleic trait in peanut Author
Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2010
Publication Date: 6/21/2011
Citation: Chu, Y., Wu, C.L., Holbrook Jr, C.C., Tillman, B., Person, G., Ozias-Akins, P. 2011. Marker-assisted selection to pyramid nematode resistance and the high oleic trait in peanut. The Plant Genome. 4:110-117. Interpretive Summary: Close cooperation between conventional plant breeders and molecular geneticist will be needed to efficiently and effectively utilize modern genetic tools in the development of peanut varieties. We have used this approach at Tifton to develop molecular markers for resistance to the peanut root-knot nematode and molecular markers for both alleles responsible for high oleic fatty acid content. We are currently utilizing these markers in an accelerated back cross breeding program to develop a high oleic version of Tifguard, a nematode resistant variety. We hybridized Tifguard with two high oleic varieties, Georgia 02C and Florida 07. We then used molecular markers to test and select the appropriate F1 plants and used these as parents to develop the first backcross generation. Use of this accelerated backcross breeding program with marker assisted selection should result in the development of a Tifguard High Oleic variety in 26 months. A conventional breeding approach without molecular markers would have taken at least 12 to 15 years.
Technical Abstract: The dynamic challenges of peanut farming demand a quick response from breeders to develop new cultivars that can cope with new problems. Application of molecular markers in peanut breeding programs can greatly compress the cultivar development process from ten to fifteen years to less than three years. With the goal to pyramid nematode resistance and the trait for high oleic to linoleic acid ratio in seeds (high O/L), nematode resistant cultivar Tifguard was used as the recurrent female parent and high O/L cultivars Georgia-02C and Florida-07 were used as donor parents for the high O/L trait. 'Tifguard High O/L' was generated through three rounds of accelerated backcrossing using heterozygous BCnF1 progenies identified with molecular markers as the pollen donors. The BC3F2 plants were allowed to self and homozygous individuals identified to obtain Tifguard High O/L. Molecular markers for nematode resistance implemented in this program are tightly linked to Rma and have minimal recombination with other Rma markers in elite x elite crosses. A high O/L cleaved amplified polymorphic sequence marker targeting the 441_ 442insA mutation in the coding region of the ahFAD2B gene was used in this breeding program and it was further converted to a more efficient HybProbe single nucleotide polymorphism marker. The accuracy of marker-assisted selection (MAS) was confirmed by phenotyping a subset of F2:3 populations from both parental combinations. Once additional molecular markers linked with traits of interest are designed to be compatible with high-throughput screening platforms, MAS will be more widely integrated into peanut breeding programs.