Molecular characterization of the flavonoid biosynthesis of Verbena hybrida and the functional analysis of verbena and Clitoria ternatea F3′5′H genes in transgenic verbena

Abstract

Homologues of the flavonoid 3′,5′-hydroxylase (F3′5′H) gene, a key gene determining flower color, were obtained from a Verbena hybrida (verbena) cultivar Temari Violet, verbena cultivar Tapien Pink, and Clitoria ternatea (butterfly pea). The expression of the Temari and butterfly pea homologues in yeast confirmed that they encoded F3′5′H. The two genes under the control of an enhanced cauliflower mosaic virus 35S promoter were introduced into verbena Temari Sakura. Some of the transgenic verbena plants had elevated delphinidin contents and flower color altered toward violet. Interestingly, the butterfly pea F3′5′H gene yielded more delphinidin and gave clearer flower color change than the verbena Temari gene in the transgenic verbena plants. The results indicate that the choice of the gene source should be considered to obtain strong phenotypic changes, even if the genes encode the same enzymatic activity. We also cloned some flavonoid biosynthetic genes from verbenas. The potential usefulness of verbena in the phytomonitoring of environmental pollutants is also discussed.