Abstract
Tetraploid landraces of wheat harbour genetic diversity that could be introgressed into modern bread wheat with the aid of marker-assisted selection to address the genetic diversity bottleneck in the breeding genepool. A novel bi-parental Triticum turgidum ssp. dicoccum Schrank mapping population was created from a cross between two landrace accessions differing for multiple physiological traits. The population was phenotyped for traits hypothesised to be proxies for characteristics associated with improved photosynthesis or drought tolerance, including flowering time, awn length, flag leaf length and width, and stomatal and trichome density. The mapping individuals and parents were genotyped with the 35K Wheat Breeders’ single nucleotide polymorphism (SNP) array. A genetic linkage map was constructed from 104 F4 individuals, consisting of 2066 SNPs with a total length of 3295 cM and an average spacing of 1.6 cM. Using the population, 10 quantitative trait loci (QTLs) for five traits were identified in two years of trials. Three consistent QTLs were identified over both trials for awn length, flowering time and flag leaf width, on chromosomes 4A, 7B and 5B, respectively. The awn length and flowering time QTLs correspond with the major loci Hd and Vrn-B3, respectively. The identified marker-trait associations could be developed for marker-assisted selection, to aid the introgression of diversity from a tetraploid source into modern wheat for potential physiological trait improvement.
Highlights
Wild relatives and ancestral landraces of wheat offer a plethora of genetic diversity that could be utilised in breeding for improved yield and environmental stability in modern wheat.Domestication from progenitor species, coupled with modern breeding techniques, has narrowed the genepool of recent varieties [1]
The largest spacing of 26.6 cM was found on chromosome 6A (Figure 2a)
High heritability was found consistently for three of the six traits measured (AL, flowering time (FT) and trichome density (TD) ) and moderate heritability was observed for the remaining traits (stomatal density (SD ), flag leaf length (FLL ) and width (FLW )) in at least one trial
Summary
Wild relatives and ancestral landraces of wheat offer a plethora of genetic diversity that could be utilised in breeding for improved yield and environmental stability in modern wheat.Domestication from progenitor species, coupled with modern breeding techniques, has narrowed the genepool of recent varieties [1]. Wild relatives and ancestral landraces of wheat offer a plethora of genetic diversity that could be utilised in breeding for improved yield and environmental stability in modern wheat. Domestication of wheat took place around 12,000 BP and included diploid wheat as well as domesticated forms of the tetraploid T. dicoccoides, predominately. Modern wheat grown today mainly belongs to two species: the hexaploid Triticum aestivum AABBDD) and the tetraploid Triticum turgidum subspecies durum (2n, 4x, 28 chromosomes; AABB), commonly known as bread and pasta wheats, respectively [3]. Diversity from a tetraploid wheat background has already been used as a genetic resource for modern wheat, in particular for disease resistance [8,9] and abiotic stress tolerance [10,11]. Introgression of beneficial traits from distant backgrounds can include the unintentional ‘linkage drag’ of co-located genes linked to undesirable characteristics [12,13]
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