Allelic Variants at the TaZds-D1 Locus on Wheat Chromosome 2DL and their Association with Yellow Pigment Content

Zeta (zeta)-carotene desaturase (ZDS) is a key enzyme in the carotenoid biosynthetic pathway, which determines the yellow pigment (YP) content in wheat (Triticum aestivum L.) grains. In the present study, the full-length DNA sequence of a ZDS gene on wheat chromosome 2DL, designated TaZds-D1, 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-D1 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-D1a and TaZds-D1b, were detected in Chinese wheat cultivars, and a functional marker, YP2D-1, was developed based on the sequence polymorphism between TaZds-D1a and TaZds-D1b. A major quantitative trait locus, located at the TaZds-D1 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-D1 locus and YP content.