*pattycabas@gmail.com

* m.ibba@cgiar.org

The yellow color in durum wheat (Triticum turgidum spp. durum) is an essential trait for breeders to meet consumer and pasta industry requirements. Given the complex inheritance of this trait, there is a continued need for new molecular markers targeting key genes, like the phytoene synthase (Psy1) gene.

This research aimed to (1) identify and characterize the allelic variants associated with Psy1-A1 and Psy1-B1 genes; (2) test previously published and newly developed molecular markers that target genes associated with the yellow index (YI); (3) perform a genome-wide association study (GWAS) analysis to validate the effectiveness of the tested markers and identify new genomic regions associated with grain yellowness.

A population of 269 durum genotypes from CIMMYT grown in three environments during 2020-2022 in Mexico was used. Thirteen molecular markers targeting specific alleles of Psy1-A1 and Psy1-B1 genes were employed. Five markers were developed at CIMMYT, while the remaining had already been published. Marker specificity was confirmed through sequence comparison and amplicon analysis. The population was genotyped with 26,349 SNPs and phenotyped for YI using the CIE b* value in semolina and whole wheat flour. Statistical analyses included phylogenetic analysis, analysis of variance, heritability estimation, and GWAS. Phylogenetic analysis elucidated the genetic diversity of Psy1-A1 and Psy1-B1 alleles across different wheat species, providing insights into their evolutionary relationships.

The study also highlighted the importance of marker specificity and genetic diversity analysis in marker development and validation. GWAS results demonstrated the potential of developed markers in predicting yellow color, with markers from Psy1-A1 and Psy1-B1 genes showing significant associations (P≤0.05).

The most significant SNPs associated with semolina and whole wheat yellowness were identified on chromosomes 5B and 7A with percentages of variance up to 22% and 10%, respectively.

Results of this research contribute to the ongoing efforts in durum wheat breeding programs of enhancing the grain YI, thereby facilitating the development of high-quality durum wheat varieties capable of meeting consumer preferences and industry standards.