Transcripts levels of Phytoene synthase 1 (Psy-1) are associated to semolina yellowness variation in durum wheat (Triticum turgidum L. ssp. durum)

Phytoene synthase 1 (Psy-1) is an essential synthesis gene influencing semolina yellowness while catalase (Cat3-A) is a catabolic enzyme that causes color loss. The main objective of this study was to evaluate the expression of Psy-A1, Psy-B1 and Cat3-A as candidate genes for semolina yellowness, using a panel of 94 durum wheat genotypes differing in yellowness. Real Time-qPCR experiments of a subset of 12 genotypes showed greater expression of Psy-A1, which specifically peaked at 35 days post-anthesis (DPA). At this time, Psy-A1 was 21-fold higher expressed in the high-yellowness relative to the low-yellowness genotypes. Psy-B1 and Cat3-A peaked at 21 DPA, suggesting different timing of expression of these genes during grain filling. The contribution of Psy-B1 was relatively higher in the genotypes showing low semolina yellowness than those with high semolina yellowness. Cat3-A did not exhibit clear differences in transcript accumulation throughout grain filling. We conclude that Psy-A1 has a major role in determining semolina yellowness, particularly in genotypes with high levels for this trait.