Micropropagation and chemical composition of Zingiber spectabile

Abstract

Zingiber spectabile (Zingiberaceae) known as ornamental ginger is an important tropical species sold as fresh cut flowers or as garden plant. Its seedling production is limited supply of this product in the market. The objective of this work was to establish the micropropagation process of this species and to study its callus chemical composition. For seed germination, MS and WPM culture media, both supplemented with 15 g L-1 sucrose were tested. Different GA3 concentrations (0.0, 0.2, 0.4, 0.6 and 0.8 mg L-1) and sucrose (15, 30 and 45 g L-1) in MS medium plus 0.1% PVP were also tested. For shoot induction using nodal segments, different BA concentrations (0.0, 0.5, 1.0, 2.0, 4.0 and 8.0 mg L-1) were tested. All culture media were solidified with 7.0 g L-1 agar. Chemical analysis was quantified in callus induced with 8.0 mg L-1 BA from nodal explants. Seeds showed better germination (58%) when inoculated in MS medium with full strength or MS supplemented with 0.4 mg L-1 GA3 (39%). The use of 15 and 30 g L-1 sucrose promoted 40% germination. Best shoot induction occurred on MS medium supplemented with 4.0 mg L-1 BA and above that concentration, a reduction on seedlings fresh weight was observed. Higher shoot height was observed in the absence of BA. The number of leaves was not affected by the treatments. In vitro rooting of ornamental ginger occurs naturally and does not need the use of exogenous auxin. The results of the callus chemical composition were: total phenols (342.8 mg 100 g-1), starch (17.8 g 100 g-1), total soluble sugar (6.8 g 100 g-1), reducing sugar (1.0 g 100 g-1), non-reducing sugar (5.5 g 100 g-1), ether extract (1.5%) and protein (13%). These compounds may help the understanding of cellular dedifferentiation processes of this species.