Regulation of chloroplast ultrastructure, adventitious bud anatomy and clonal fidelity of in vitro Zingiber officinale var. rubrum Theilade plantlets in response to LED spectral quality

Abstract

Light quality plays a major role in deciding plant physiological processes during growth and development as it interacts with the photoreceptors to induce a cascade of events with reversible and non-reversible outcomes. Hence, the present study was focused on conducting qualitative analysis on the effects of different light qualities on chloroplast ultrastructure, adventitious bud anatomy, and genetic fidelity of 12 weeks old in vitro Zingiber officinale var. rubrum Theilade. The study was conducted by integrating white (400–700 nm), far-red (720 nm), blue (460 nm), green (530 nm), red (660 nm), and dichromatic purple (400–660 nm) light-emitting diodes (LEDs). Chloroplasts under white, blue, and purple LEDs showed well-developed grana thylakoid and stroma thylakoid. Far-red, green, and red LEDs distorted chloroplast ultrastructure with an accumulation of starch grains. LED mediated spectral quality customised within the visible spectrum retained meristematic characteristics, vascular initiation, and oleoresin accumulation in the adventitious bud. Furthermore, clonal fidelity assessed using direct amplification of minisatellite DNA regions (DAMD) markers revealed genetic similarities of more than 99% for plantlets regenerated under LED irradiation. The results demonstrated that micropropagation systems integrated with LED spectral quality alters plant chloroplast ultrastructure by the effects on starch accumulation but produced normal adventitious bud phenology. A high genetic similarity percentage suggests effective and promising application of LED spectrum to produce true to type in vitro Z. officinale var. rubrum Theilade plantlets.