Abstract
BackgroundIncreasing wheat (Triticum aestivum L.) production is required to feed a growing human population. In order to accomplish this task a deeper understanding of the genetic structure of cultivated wheats and the detection of genomic regions significantly associated with the regulation of important agronomic traits are necessary steps. To better understand the genetic basis and relationships of adaptation and yield related traits, we used a collection of 102 Argentinean hexaploid wheat cultivars genotyped with the 35k SNPs array, grown from two to six years in three different locations. Based on SNPs data and gene-related molecular markers, we performed a haplotype block characterization of the germplasm and a genome-wide association study (GWAS).ResultsThe genetic structure of the collection revealed four subpopulations, reflecting the origin of the germplasm used by the main breeding programs in Argentina. The haplotype block characterization showed 1268 blocks of different sizes spread along the genome, including highly conserved regions like the 1BS chromosome arm where the 1BL/1RS wheat/rye translocation is located. Based on GWAS we identified ninety-seven chromosome regions associated with heading date, plant height, thousand grain weight, grain number per spike and fruiting efficiency at harvest (FEh). In particular FEh stands out as a promising trait to raise yield potential in Argentinean wheats; we detected fifteen haplotypes/markers associated with increased FEh values, eleven of which showed significant effects in all three evaluated locations. In the case of adaptation, the Ppd-D1 gene is consolidated as the main determinant of the life cycle of Argentinean wheat cultivars.ConclusionThis work reveals the genetic structure of the Argentinean hexaploid wheat germplasm using a wide set of molecular markers anchored to the Ref Seq v1.0. Additionally GWAS detects chromosomal regions (haplotypes) associated with important yield and adaptation components that will allow improvement of these traits through marker-assisted selection.
Highlights
Increasing wheat (Triticum aestivum L.) production is required to feed a growing human population
Haplotype-based gWAS analysis Fruiting efficiency at harvest (FEh): We identified 17 haplotypes/markers associated with fruiting efficiency at harvest (FEh) of which one belongs to chromosome 1A, seven to 2A, Table 3 Broad sense heritability (H2) and variance components for the best linear unbiased predictors (BLUPs) of five traits across the tested environments
The genetic structure of the Argentinean hexaploid wheat collection was determined by the use of single nucleotide polymorphism (SNP) markers, in which a strong relationship was displayed between the subpopulations obtained and the germplasm origin used by the main breeding programs in the country
Summary
Increasing wheat (Triticum aestivum L.) production is required to feed a growing human population. Satisfying the increasing feed and food demand will mainly come from yield improvement: it will be required that wheat yield (and other staple crops) be increased by at least 50% in the few decades [2], which will depend, among other components, on improving yield potential [3] This scenario becomes more complex if we consider that each degree-Celsius increase in global mean temperature would, on average, reduce global and in particular Argentinean wheat yields by 6.0% [4, 5]. Crop management will need to be environmentally more sustainable in the future [1] Under this restrictive context, yield genetic gain will be required to increase by 1.16–1.31% per year to satisfy the projected demand of cereals for food, feed and biofuels by 2050 [6]. Genetic gains reported in wheat from different countries for the last decades seem to have been increasing less than required [7,8,9]
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