A High-Density SNP and SSR Consensus Map Reveals Segregation Distortion Regions in Wheat

Abstract

Segregation distortion is a widespread phenomenon in plant and animal genomes and significantly affects linkage map construction and identification of quantitative trait loci (QTLs). To study segregation distortion in wheat, a high-density consensus map was constructed using single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers by merging two genetic maps developed from two recombinant-inbred line (RIL) populations, Ning7840 × Clark and Heyne × Lakin. Chromosome regions with obvious segregation distortion were identified in the map. A total of 3541 SNPs and 145 SSRs were mapped, and the map covered 3258.7 cM in genetic distance with an average interval of 0.88 cM. The number of markers that showed distorted segregation was 490 (18.5%) in the Ning7840 × Clark population and 225 (10.4%) in the Heyne × Lakin population. Most of the distorted markers (630) were mapped in the consensus map, which accounted for 17.1% of mapped markers. The majority of the distorted markers clustered in the segregation distortion regions (SDRs) on chromosomes 1B, 2A, 2B, 3A, 3B, 4B, 5A, 5B, 5D, 6B, 7A, and 7D. All of the markers in a given SDR skewed toward one of the parents, suggesting that gametophytic competition during zygote formation was most likely one of the causes for segregation distortion in the populations.

Development of DNA Markers Linked to Double-Flower and Hortensia Traits in <i>Hydrangea macrophylla</i> (Thunb.) Ser.

“…Another possibility is that a transcription factor controls both traits or induces a factor for recombination in this region. Segregation distortion can also arise because of conscious or unconscious selection by researchers during the mapping of populations (Li et al, 2015). Further analysis is required to clarify the cause of the skewed segregation in our study.…”

“…The reason for the skewed segregation in our study is unclear. Segregation distortion is a common phenomenon in many plants and is recognized as a potentially powerful evolutionary force (Li et al, 2010;Li et al, 2015); however, its underlying mechanism is not understood (Cai et al, 2015). Suggested causes include aneuploidy, chromosomal translocation, competition among gametes, and the inheritance of alleles affecting the viability of the zygote, embryo, or seedling (Lashermes et al, 2001).…”

Harnessing Genetic Diversity of Wild Gene Pools to Enhance Wheat Crop Production and Sustainability: Challenges and Opportunities

“…SD is likely to represent one result of genetic incompatibilities between parental genomes that have been separated by reproductive barriers [48]. In this view, it is not surprising to find the level of SD to increase, both in the number of SD regions (SDRs) within a chromosomal set, and in the number of markers within each SDR, in intraspecific cross progeny involving genetically and geographically more distant parents [49]. In contrast to the latter work, which was carried out on wheat, a recent study on F 2 populations generated from several Arabidopsis thaliana accessions showed little correlation between the degree of genetic differentiation between the parental accessions and the probability of observing allelic distortion in their progeny [50].…”

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“…This strategy ensures the accuracy and a high coverage of the final map. Similar strategies were successfully used for linkage mapping in different species, e g., of olive (Khadari et al 2010), globe artichoke and cardoon (Martin et al 2013), lentil (Verma et al 2015), poplar (Zhou et al 2015), and wheat (Li et al 2015).…”