Zeta (Q-carotene desaturase (ZDS) is a key enzyme in the carotenoid biosynthetic pathway, which determines the yeliow pigment (YP) content in wheat {Triticum aestivum L.) grains. In the present study, the fuil-length DNA sequence of a ZDS gene on wheat chromosome 2DL, designated TaZds-DI, was characterized. The TaZds-D1 gene has an open reading frame of 1707 bp, including 13 introns and 14 exons, and a deduced peptide containing 568 amino acid residues with a predicted molecular weight of 62.5 kDa. The TaZds-Dl gene was located on chromosome 2DL based on polymerase chain reaction amplifications of Chinese Spring nullisomic-tetrasomic lines, Langdon-Chinese Spring D-genome chromosome disomic substitution lines, and Rusty D-genome chromosome disomic substitution lines as well as linkage analysis. Two allelic variants, TaZds-Dia and TaZds-D1b, were detected in Chinese wheat cultivars, and a functional marker, YP2D-1, was developed based on the sequence polymorphism between TaZds-Dla and TaZds-Dlb. A major quantitative trait locus, located at the TaZds-Dl region in the marker interval of YP2D-1 and Xgwm157 on chromosome 2DL, explained 18.4% of the phenotypic variance for YP content in a doubled haploid population derived from the cross Zhongyou 9507/CA 9632. This confirmed the association between allelic variation at the TaZds-Dl locus and YP content.

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