Transgenic plants with blue flower color, or their inbred or outbred progeny, or their propagules, partial plant bodies, tissues or cells, are provided. A buckwheat-derived C-glucosyltransferase (CGT) gene or its homolog is transferred into a host plant to cause delphinidin-type anthocyanins and flavone mono-C-glycosides to be copresent in the plant cells.

The present invention relates to a recombinant microbial host cell producing a tetraketide or derivatives thereof from one or more substrates selected from cinnamoyl-CoA, p-Coumaroyl-CoA, Caffeoyl-CoA, Feruloyl-CoA, malonyl-CoA, sinapoyl-CoA and dihydro derivatives thereof, comprising an operative biosynthetic metabolic pathway for the tetraketide or derivatives thereof comprising a chalcone isomerase-like (CHIL) polypeptide heterologous to the host cell and a Type 3 polyketide synthase (PKS).

Transgenic plants with blue flower color, or their inbred or outbred progeny, or their propagules, partial plant bodies, tissues or cells, are provided. A buckwheat-derived C-glucosyltransferase (CGT) gene or its homolog is transferred into a host plant to cause delphinidin-type anthocyanins and flavone mono-C-glycosides to be copresent in the plant cells.