Differential Expression of Three Flavanone 3-Hydroxylase Genes in Grains and Coleoptiles of Wheat

Abstract

Flavonoid pigments are known to accumulate in red grains and coleoptiles of wheat and are synthesized through the flavonoid biosynthetic pathway. Flavanone 3-hydroxylase (F3H) is a key enzyme at a diverging point of the flavonoid pathway leading to production of different pigments: phlobaphene, proanthocyanidin, and anthocyanin. We isolated threeF3Hgenes from wheat and examined a relationship between their expression and tissue pigmentation. ThreeF3Hs are located on the telomeric region of the long arm of chromosomes 2A, 2B, and 2D, respectively, designated asF3H-A1,F3H-B1, andF3H-D1. The telomeric regions of the long arms of the chromosomes of homoeologous group 2 of wheat showed a syntenic relationship to the telomeric region of the long arm of rice chromosome 4, on which riceF3Hgene was also located. All three genes were highly activated in the red grains and coleoptiles and appeared to be controlled by flavonoid regulators in each tissue.