Influence of isolation technique of half-anthers and of initiation culture medium on callus induction and regeneration in Anthurium andreanum

Optimization of the isolation technique and initiation culture medium are two critical aspects that can determine the success of anthurium half-anther culture. Both aspects in half-anther culture of Anthurium andreanum Linden ex Andr, cv. 'Tropical' were studied and successfully improved. Untreated half-anthers, when cultured abaxial side down on medium, was the most suitable means of inducing callus. Callus formation was further improved by culturing half-anthers adaxial side down on Winarto-Teixeira (WT) medium (Winarto et al. in Plant Growth Regul 65:513-529, 2011b) supplemented with 0.01 mg/l alpha-naphthaleneacetic acid (NAA), 1.0 mg/l 6-benzyladenine (BA) and 0.5 mg/l thidiazuron (TDZ). Gelrite enhanced callus formation (compared to agar) when the concentration was reduced from 2.0 to 1.5 g/l on WT medium. Application of 0.5 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) in WT medium increased callus formation. Most callus formed when half-anthers were cultured adaxial-side down on WT medium supplemented with 0.5 mg/l 2,4-D in combination with 0.01 mg/l NAA, 1.0 mg/l BA and 0.5 mg/l TDZ using 1.5 g/l Gelrite. This ideal medium induced the growth of half-anthers, with as much as 38 % of half-anthers producing callus, or, on average, 3.4 half-anthers/treatment. Callus derived from this optimized protocol regenerated easily and could be multiplied on New Winarto-Teixeira medium (NWT) (Winarto et al. in Plant Growth Regul 65:513-529, 2011b) containing 0.25 mg/l 2,4-D, 0.02 mg/l NAA, 0.75 mg/l BA, 1.5 mg/l TDZ and 2.0 g/l Gelrite. Shoots rooted well on hormone-free NWT medium with 2.0 g/l Gelrite. The plantlets could be easily acclimatized in a substrate of raw rice husk, burned-rice husk and organic manure (1:1:1, v/v/v) with a high survival (100 %) ex vitro in a greenhouse. The results of this study would benefit half-anther culture of other Anthurium cultivars, particularly at the initial stage of callus induction.