Physical localization of a novel blue-grained gene derived from Thinopyrum bessarabicum

Blue wheat grain contains different groups of pigments that can be used for making specialty foods or as food colorants. Thinopyrum bessarabicum , a wild relative of wheat, carries a blue-grained gene on chromosome 4J. In this study, we analyzed the mitotic chromosomes of 159 F7 lines derived from the cross between Triticum aestivum cv. Chinese Spring (CS) and a CS– Th. bessarabicum amphiploid by using multi-color fluorescence in situ hybridization, genomic in situ hybridization, and newly developed chromosome 4J-specific DNA markers. Intact chromosome 4J and various 4J chromosomal segments were identified in the 159 lines. The blue-grained gene of Th. bessarabicum was physically localized to the region between the centromere and FL0.52 on chromosome arm 4JL. The chromosomal location of this gene differed from the location of previously reported blue-grained genes. In addition, a strong dosage effect was observed with this gene. These results suggest that the blue-grained gene in Th. bessarabicum represents a novel gene locus for blue aleurone, designated BaThb . The wheat lines and 4J chromosome-specific molecular markers developed in this study will facilitate the introgression and utilization of BaThb for wheat nutritional quality improvement.