Effects of Explant Source and Dark-preconditioning on Adventitious Bud Formation in Neofinetia falcata H. H. Hu in vitro

Abstract

Tissue culture methods were investigated for propagation of the epiphytic orchid Neofinetia falcata H. H. Hu. The protocorms were divided into upper and lower portions and cultured. An average of 1.0-1.7 plantlets per explant were derived from upper portions which had survived at frequencies at 10-30%. Plantlets that developed from protocorms were cultured to increase the survival rate. All explants derived from upper portions of the plantlets survived, but explants from lower portions of plantlets did not. Explants derived from darkpreconditioned plantlets showed multiple bud formation when grown on medium containing 0.44 μM N 6 -benzyladenine (BA) and 5.37 μM α-naphthaleneacetic acid (NAA). Leaf explants derived from darkpreconditioned plantlets produced adventitious buds most efficiently when cultured in medium containing 0.44 μM BA and 5.37 μM NAA. These results suggest that the most suitable culture materials for bud formation in N. falcata are the upper portion of plantlets and the leaves of dark-preconditioned plantlets.

L-2-aminooxy-3-phenylpropionic acid (AOPP) Controls Browning and Promotes Adventitious Bud Formation in Neofinetia falcata in vitro

“…In N. falcata, treatment with AOPP controlled phenol compound biosynthesis in the explants and promoted adventitious bud formation, which were similar to the effects of dark preconditioning (Mitsukuri et al, 2009); however, dark preconditioning needs to find the conditioning period of each plant. In our previous study, dark preconditioning reduced the explant survival rate and preconditioned plantlets formed 5.1 buds per survived explant (Mitsukuri et al, 2009).…”

“…(Wang et al, 1994), Psidium guajava (Meghwal et al, 2001), and Mangifera indica (Sharma and Singh, 2002), which increases bud formation. In our previous study, we found that dark preconditioning was an effective treatment for browning control and promotion of bud formation in N. falcata (Mitsukuri et al, 2009).…”

“…The concentrations of N 6 -benzyladenine (BA) and α-naphthaleneacetic acid (NAA) in the medium were limited to an effective combination (0.44 μM BA and 5.37 μM NAA) (Mitsukuri et al, 2009). The pH of the medium was adjusted to 5.6, and 50 mL medium was dispensed into 100 mL Erlenmeyer flasks before autoclaving at 121°C for 15 min.…”

“…Our previous experiments showed that a browning compound is exuded into the medium from the cut surface of orchid explants and decreased the survived explant rate and bud formation by explants (Mitsukuri et al, 2009). In shoot apex cultures of Cattleya Lindl., browning of the culture medium was caused by a phenolic compound (Ishii et al, 1979).…”

“…Shimasaki (1993) induced protocorm-like bodies (PLBs) from young inflorescence explants in vitro. We recently reported that the upper portion of the plantlet and leaves of dark preconditioned plants are the most suitable tissue materials for bud formation by N. falcata because of browning of the explants and medium (Mitsukuri et al, 2009). However, dark preconditioning takes time and decreases the explant survival rate; therefore, a more simple method is required for tissue culture of N. falcata.…”