Marker-Trait Associations for Total Carotenoid Content and Individual Carotenoids in Durum Wheat Identified by Genome-Wide Association Analysis

Abstract

Yellow pigment content is one of the main traits considered for grain quality in durum wheat (Triticum turgidum L.). The yellow color is mostly determined by carotenoid pigments, lutein being the most abundant in wheat endosperm, although zeaxanthin, α-carotene and β-carotene are present in minor quantities. Due to the importance of carotenoids in human health and grain quality, modifying the carotenoid content and profile has been a classic target. Landraces are then a potential source for the variability needed for wheat breeding. In this work, 158 accessions of the Spanish durum wheat collection were characterized for carotenoid content and profile and genotyped using the DArTSeq platform for association analysis. A total of 28 marker-trait associations were identified and their co-location with previously described QTLs and candidate genes was studied. The results obtained confirm the importance of the widely described QTL in 7B and validate the QTL regions recently identified by haplotype analysis for the semolina pigment. Additionally, copies of the Zds and Psy genes on chromosomes 7B and 5B, respectively, may have a putative role in determining zeaxanthin content. Finally, genes for the methylerythritol 4-phosphate (MEP) and isopentenyl diphosphate (IPPI) carotenoid precursor pathways were revealed as additional sources of untapped variation for carotenoid improvement.

Bread Wheat Biofortification for Grain Carotenoid Content by Inter-Specific Breeding

“…However, the parental line 12THES4515 also carries a functional XAT-7D allele, but it has low carotenoid content. Thus, the higher carotenoid content of KN × THES progenies compared with KN × C29 suggests that other carotenoid-related genes are playing an important role in the cross KN × THES, in agreement with previous knowledge in wheat [ 6 , 8 ]. Indeed, a total of 124 significant marker-trait associations for lutein content were reported in common wheat, covering 18 out of 21 wheat chromosomes [ 7 ] and with six stable QTL on chromosomes 2AL, 2DS, 3BL, 3DL, 7AL and 7BS.…”

“…Indeed, a total of 124 significant marker-trait associations for lutein content were reported in common wheat, covering 18 out of 21 wheat chromosomes [ 7 ] and with six stable QTL on chromosomes 2AL, 2DS, 3BL, 3DL, 7AL and 7BS. Similar results have been obtained in durum wheat, with the identification of marker-trait associations for lutein and zeaxanthin grain content in several chromosomes [ 8 ]. These findings highlight the importance of other chromosome regions beyond Psy1 genes for lutein accumulation in wheat.…”

“…Alternatively, spectrophotometric determinations using the AACC-approved method 14–50 are also used, although this method is more expensive, slower and has higher technical requirements than the previous one. In addition, many efforts have been dedicated to the identification of the genetic bases controlling YPC either by the identification of QTL using bi-parental populations, or by the detection of marker-trait associations using diversity panels reviewed by [ 6 ] with new target regions for specific carotenoids being identified in recent expanded analyses of wheat biodiversity [ 7 , 8 ]. However, it is widely known that the main QTLs for YPC content in both durum and bread wheat are located in the long arm of chromosomes 7A and 7B [ 4 , 5 , 9 , 10 , 11 , 12 , 13 ].…”

Genetic approaches to exploit landraces for improvement of Triticum turgidum ssp. durum in the age of climate change

“…In addition, genes related to quality such as pasta-making quality and color of semolina and other durum wheat-end products were also divergent between landraces and modern cultivars. In detail, loci for gluten composition (HMW/LMW, high/low molecular weight, and a, b, g, and ώ gliadins), as well as loci involved in the carotenoid pathway (Psy) and polyphenol oxidase reaction (Ppo) were identified in hotspot regions (Requena-Ramıŕez et al, 2022;Taranto et al, 2022). Other divergent loci with implications in disease resistance, plant-microbe interactions, abiotic stresses, and plant development corresponded to gene models involved in important biological functions (Soriano et al, 2021).…”

Association of High-Molecular-Weight Glutenin Subunits with Grain and Pasta Quality in Spring Durum Wheat (Triticum turgidum spp. durum L.)

“…Improvements in gluten strength are most likely associated with the replacement of the Glu-B1e allele (Bx20 + By20) with the Glu-B1b (Bx7 + By9) and Glu-B1d (Bx6 + By8) high-molecularweight glutenins (HMW-GS), the positive effect of low-molecular-weight glutenin (LMW-GS) subunits of the LMW-2 group, and the γ-45 subunit of gliadin associated with high firmness and viscoelasticity of pasta [11][12][13]15,[18][19][20]. Identifying alleles (including novel ones) with a positive impact on quality and implementing them into the breeding process is facilitated by classic methods of protein (SDS-PAGE) and molecular genetic analysis (PCR), as well as modern approaches such as Lab-on-a-Chip [21], KASP [22,23], and GWAS-based markers [24,25].…”