Ectopic expression of the R2R3-MYB gene from Tricyrtis sp. results in leaf color alteration in transgenic Pelargonium crispum

Abstract

Abstract R2R3-MYB transcription factors are known to activate the flavonoid biosynthetic pathway. In the present study, R2R3-MYB gene isolated from the liliaceous ornamental plant Tricyrtis sp. (TrMYB1) under the control of the cauliflower mosaic virus 35S promoter was introduced into Pelargonium crispum via Agrobacterium-mediated transformation in order to alter leaf color phenotype. Ten independent transgenic plants have been obtained, and they could be classified into three types according to the leaf color phenotype: six transgenic plants had deep yellowish-green leaves as non-transgenic plants (Type I); two had deep red-purple leaves (Type II); and two had deep red leaves (Type III). Spectrophotometric analysis showed that the amount of total anthocyanins significantly increased in leaves of Type II and Type III transgenic plants compared with non-transgenic and Type I transgenic plants. In addition, several anthocyanins were newly produced in leaves of Type II and Type III transgenic plants as revealed by high performance liquid chromatography analysis. Quantitative real-time reverse transcription-polymerase chain reaction analysis showed that TrMYB1 expression level correlated with the degree of leaf color alteration. Our results indicate the validity of genetic transformation with TrMYB1 for producing colored foliage in heterologous ornamental plants.