High throughput mapping and transcriptome analyses revealed the controlling gene of blue wheat grains

Blue grained wheat possesses a high amount of natural anthocyanin compounds with high antioxidant activity while the favorable characteristics which are not present in normal commercial wheat varieties. At present, major genes related to several colors of wheat have been identified. However, the major genes or control mechanism of anthocyanin biosynthesis in blue wheat is still unrevealed. Hence, combining the information of the chromosomal location of blue grain trait, and genes screened out from transcriptome analysis, we attempt to find the pivotal genes regulating blue grain trait in wheat. SNP genotyping was carried out in an F₂ blue and white wheat population. The results showed that blue grain was controlled by a gene/locus located between two SNP markers IWB18525 and IWB16381 on 4D chromosome. Comparative transcriptome analysis of two blue and eight non-blue wheat grain samples was carried out to identify the candidate genes controlling the blue grain trait. Forty structural differentially expressed genes (DEGs) related to anthocyanin biosynthesis had significant expression differences between blue and non-blue samples. Among them, 12 DEGs expressed only in blue grain samples while two transcription factor DEGs were specific to blue wheat. These candidate genes were distributed in different chromosomes. Among them, only two F3’5’H genes located in 4D (Traes_4DL_27C195FDE, Traes_4DL_5A3D8F519) were consistent with the location results performed in SNP genotyping. Meanwhile, F3’5’H is the main enzyme required for the production of Delphinidin compounds, which give the blue coloration. This study reports two candidate genes encoding F3’5’H in 4D chromosome responsible for the blue pigmentation in wheat.