Allelic variants of phytoene synthase 1 (Psy1) genes in Chinese and CIMMYT wheat cultivars and development of functional markers for flour colour

Abstract

Phytoene synthase genes influence yellow pigment (YP) content in wheat grain, and are associated with the quality of end-use products. In the present study, a suite of 217 Chinese winter wheat cultivars and 342 CIMMYT spring wheat cultivars were used to search for phytoene synthase 1 gene variations and to detect and compare their genetic effects in different genetic backgrounds. An initial focus on the Chinese winter wheat cultivars revealed four allelic variants of this gene on chromosome 7B (Psy-B1), designated as Psy-B1a, Psy-B1b, Psy-B1c and Psy-B1d. The frequencies of these four alleles were 39.6, 43.8, 15.7 and 0.9%, respectively. A co-dominant marker YP7B-1 based on a 5-bp InDel of poly C in the fifth intron of Psy-B1 amplified a 151-bp PCR fragment in accessions with the medium YP content allele Psy-B1a, and a 156-bp fragment in lower YP content accessions with Psy-B1b. Two dominant markers YP7B-2 (428 bp) and YP7B-3 (884 bp) were designed for accessions with Psy-B1c and Psy-B1d, respectively. Allele Psy-B1c was associated with high YP content, but the phenotypic effect of Psy-B1d was not determined due to the limited number of accessions. In CIMMYT spring wheat cultivars, Psy-B1a, Psy-B1b, Psy-B1d and a further allelic variant, Psy-B1e, were detected with frequencies of 50.6, 29.2, 19.6 and 0.6%, respectively. Psy-B1c was not found in the CIMMYT germplasm. However, no significant differences were detected for mean YP content among CIMMYT wheat lines with different Psy-B1 genotypes. A new allelic variant of Psy-A1, designated Psy-A1c, was identified in three CIMMYT wheat lines, and this allele was associated with higher YP content.