Low Concentration of Anti-Auxin and Anti-Fungal Agent Accelerates the PLB Regeneration of Dendrobium okinawense under Green LED

Abstract

Dendrobium okinawense is an endangered epiphytic orchid, and there has been no scientific report so far on its propagation. Protocorm is a mass of cells, and protocorm-like bodies (PLBs) are lookalike protocorms produced by vegetative explants in vitro. Regeneration of PLBs is a widely used technique for orchid micropropagation. We used different light-emitting diodes (LEDs) for the PLB regeneration of D. okinawense. The number of PLBs and fresh weight were increased by 81.1% and 80.8%, respectively, under green LED over the white fluorescent (WF) light. We added different concentrations of PCIB (p-Chlorophenoxyisobutyric acid, an anti-auxin) and HMI (3-Hydroxy-5-methyl isoxazole, an anti-fungal agent) in culture media. The number of PLBs was increased in media having 0.01 mg/L of PCIB (35.9%) compared to control (no PCIB), whereas 19.3% increased in media having 0.01 mL/L of HMI compared to control (no HMI). Green LED in combination with 0.01 mg/L of PCIB significantly increased the number of PLBs (69.0%) compared to the WF–without PCIB combination. In LEDs-PCIB and LED-HMI combinations, HMI did not show better PLBs regeneration compared with PCIB. The results suggested that a combination of low concentrations of PCIB and green LED have the potential to accelerate PLB regeneration of D. okinawense.

Tissue Culture in Ornamentals: Cultivation Factors, Propagation Techniques, and Its Application

“…From the above discussion, it is clear that exogenous carbohydrate supplements are crucial for in vitro plant growth and development. Exogenous carbohydrate concentration is also varied, and concentrations over a threshold level could be toxic, hamper photosynthesis, and inhibit in vitro plant growth [ 30 , 31 , 32 ].…”

“…Very little information is available on the effect of green LED on in vitro micropropagation of ornamentals. In recent studies, it was found that green LED increased PLB regeneration in Dendrobium [ 31 ], and Cymbidium [ 64 ]; however, PLB generation was more efficient under green LED when culture media had anti-auxin, PCIB ( p -Chlorophenoxyisobutyric acid, an anti-auxin), in D. okinawense [ 31 ]. Additionally, yellow and orange light spectra have also been reported, respectively, in PLB, shoot, and plantlet regeneration of Dendrobium and seed germination and rhizoid development of Bletilla ochracea ( Supplementary Table S4 ).…”