Regeneration of Gynura aurantiaca ‘Purple Passion’ via indirect shoot organogenesis

Abstract

Gynura aurantiaca (Blume) DC ‘Purple Passion’ is an important ornamental foliage plant. Its purple-colored leaves contain acylated anthocyanins which have potential to be natural food colorants. Production of this crop requires healthy and uniform starting materials or propagules. This study developed simple and efficient protocols for regenerating ‘Purple Passion’ through indirect shoot organogenesis. Reddish, purple colored callus was induced from leaf explants cultured on MS basal medium supplemented with 2.0 mg L−1 TDZ or 2.0 mg L−1 BA in combination with 0.5 mg L−1 2,4-D. Callus pieces (5 mm3) were cultured on the same medium with the same concentrations of TDZ or BA with 2,4-D for inducing adventitious shoots. More than 25 adventitious shoots were produced per callus piece. Microcuttings derived from the shoots were easily rooted in vitro, and rooted cuttings were transplanted into a peat-based substrate and grown in a shaded greenhouse. Plants grew vigorously in the shaded greenhouse with a high survival rate. They were morphologically stable without any phenotypic variation. Chromosome numbers of randomly selected regenerated plants and stock plants were the same with 2n = 40. Additionally, reddish, purple callus had significantly higher content of anthocyanins than leaves of regenerated plants grown in the shaded greenhouse, suggesting that callus induced through the established protocols could be used to produce acylated anthocyanins as natural food colorants through bioreactor culture.