Peer review

Population structure and linkage disequilibrium (LD) were investigated in a set of 395 bread wheat landraces including 154 spring, 193 winter, two facultative wheat and 46 unknown growth type collected from different geographical regions of Iran. A total of 53 microsatellite markers distributed in three genomes of wheat were assayed for polymorphism. The 312 polymorphic alleles were served to estimate population structure and analyse the genome-wide LD. The number of alleles ranged from 2 to 18 with an average of 5.89 alleles/locus. Mean of polymorphic information content was 0.6 with a range of 0.15-0.86 and gene diversity varied from 0.16 to 0.88 with an average of 0.64. The population of landraces was highly structured and based on distance- and model-based cluster analyses the 395 landraces were assigned into eight subpopulations: SG1-SG8. Population structure estimates based on simple sequence repeat (SSR) marker data were quantified in a Q matrix and used in calculation of LD between pair of markers. A low overall LD level found in 12-13% (166) of the SSR marker pairs showed significant pairwise LD in r2 ≥ 0.01 and P ≤ 0.001 and six pair showed r2 ≥ 0.05 with P ≤ 0.001. LD clearly decays within the genetic distance of 40-60 cM with r2*0.05. The results of this study should provide valuable information for future association mapping using this wheat collection.

Wheat CRP FP2 - Novel diversity and tools adapt to climate change and resource constraints

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