Effects of plant growth regulators and light quality on in vitro morphogenesis and physiological and biochemical responses in Angelica gigas

Angelica gigas is a medicinal plant valued for pyranocoumarins, including decursinol angelate. This study examined gibberellic acid (GA₃)-dependent in vitro morphogenesis and light quality-specific changes in growth, photosystem II (PSII) performance, antioxidant responses, and decursinol angelate accumulation. Single-shoot explants were cultured on Murashige and Skoog medium supplemented with 5 µM 6-benzylaminopurine, thidiazuron, zeatin, or GA₃, followed by evaluation of 1, 5, and 10 µM GA₃. Explants under the selected GA₃ condition were then exposed to fluorescent light or white, green, red, and blue light-emitting diodes (LEDs). Growth, shoot induction, somatic embryo formation, chlorophyll fluorescence, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity, decursinol angelate concentration, and antioxidant enzyme activities were assessed. Among the tested plant growth regulators, 5 µM GA₃ produced the most favorable growth and regeneration responses. In the concentration experiment, 1 µM GA₃ showed the highest shoot induction and somatic embryo formation, whereas 10 µM GA₃ resulted in the greatest shoot elongation. Green LED showed the highest fresh-weight increase and shoot length increment, while blue LED produced the highest shoot induction. Blue LED also showed the highest Fv/Fm, PI_abs, and ETo/RC values and the lowest ABTS IC₅₀. Red LED produced the highest measured decursinol angelate concentration, was the only treatment exceeding the limit of quantification, and showed the highest superoxide dismutase (SOD) and peroxidase (POD) activities. Principal component analysis separated the LED treatments according to distinct morphogenic, photochemical, and biochemical response profiles. Plant growth regulator treatments and light quality elicited distinct morphogenic, physiological, and biochemical responses in A. gigas in vitro cultures. These findings support selecting culture conditions according to the intended objective, including biomass accumulation, shoot formation, or decursinol angelate production.