RNAi-induced silencing in floral tissues of Petunia hybrida by agroinfiltration: a rapid assay for chalcone isomerase gene function analysis

Abstract

Variegation in flower color is commonly observed in many plant species and also occurs on Petunia (Petunia hybrida) as an ornamental plant. Variegated plants are of highly valuable in the floricultural market. Agroinï¬ltration is an Agrobacterium-mediated transient assay for the analysis of gene function and genetic modiï¬cation in leaves, flowers and fruit tissues of various plants. Transient RNAi-induced silencing by agroinï¬ltration has been developed in leaves and fruits of several plant species. Here we report the establishment of a transient hairpin RNAi-induced silencing system for color modiï¬cation assay in floral tissues of Petunia with different colors. chiRNAi construct was cloned into the pBI121 vector under the control of 35S promoter. Transient RNA silencing of chi in the floral tissues of Petunia was induced by delivering 530 bp chi hairpin RNAs (hpRNAs) into the petals of flowers using agroinï¬ltration. Impaired anthocyanin accumulation and reduction of endogenous mRNAs of the corresponding targets were observed in the inï¬ltrated areas of the petals of four colors of Petunia. Silencing of the endogenous chi mRNAs was highly effective in reduction of chi gene and anthocyanin accumulation. This transient silencing system is a prototype for modiï¬cation of the anthocyanin biosynthetic pathway in Petunia through chi gene suppression.