Allelic variation of carotenoid biosynthesis and degradation genes across worldwide commercial durum wheat (Triticum turgidum ssp. durum) varieties under contrasting water regimes

Abstract

Carotenoids are the pigments responsible for the yellow colour of durum wheat semolina, a key quality trait for pasta production. This study evaluated 46 commercial durum wheat cultivars grown under irrigated and drought-simulated conditions in the Yaqui Valley (Mexico), measuring yellow pigment content (YPC) and yellow pigment loss (YPL) under simulated processing conditions. Cultivars under the full irrigation system increased YPC (7.3 mg/kg) and reduced YPL (13.3 %) compared to cultivars under drip irrigation system or simulated drought (YPC 6.6 mg/kg; YPL 15.3 %), indicating that probably water limitation reduces carotenoid accumulation and enhances pigment degradation. Allelic variation in carotenoid biosynthesis genes (PSY-A1, PSY-B1, PDS-B1, ZDS-A1) and degradation genes (LPX-A3, LPX-B1.1) was assessed. Psy-A1o, Psy-B1n, and TdZds-A1.2 alleles were associated with higher YPC, while Lpx-B1.1c contributed to lower pigment loss. No significant effects were observed for PDS-B1 or LPX-A3, and no cultivar carried all favourable alleles simultaneously, highlighting the potential for further improvement and pyramiding of carotenoid-related traits. This study provides molecular markers and genotype information for breeding programs aimed at improving semolina and pasta colour, offering strategies to enhance pigment retention under contrasting water regimes.