Comparative anatomical and biochemical studies of in vitro and in vivo plants of ginger

In vitro propagation offers disease-free material in ginger (Zingiber officinale Rosc.), a plant of significant medicinal and commercial value. This study aims to investigate the anatomical and biochemical characteristics of in vitro and in vivo plants of ginger. Fifty-day-old in vitro (developed from tissue culture lab maintained at 25 ± 2°C and 90-92% RH over 14 h photoperiod at 3000 lx) and in vivo plants (pro-tray plants grown in polyhouse maintained at 25 ± 2°C and 60-70% RH) of the ginger variety IISR Varada were taken to be studied at the ICAR—Indian Institute of Spices Research, Kerala, India. Transverse sections of leaves, the pseudo-stem, and the rhizomes of the in vitro and in vivo ginger plants were taken and visualized under light microscopy.
In vitro and in vivo ginger possess similar leaf structures but differ in their spongy parenchyma thickness, the number of stomata, oil cells, and air canals, and their vascular bundle distribution. The in vitro pseudo-stems had a closely bound leaf sheath and epidermis unlike their in vivo counterparts. Rhizome analysis revealed larger vascular bundles in the in vivo ginger (normal rhizomes produced at farm) and higher starch and sugar content in the in vitro rhizomes (micro-rhizomes developed at tissue culture lab).
Biochemical analysis revealed that the total chlorophyll and carotenoid content was significantly higher in the in vivo ginger (1.1989 mg/g and 67.24 mg/g) compared to the in vitro ginger (0.7173 mg/g and 50.87 mg/g, respectively). Furthermore, the enzyme activities of peroxidase (0.063 mg/g), catalase (108.248 U/g), and superoxide dismutase (0.367 U/g); the starch content (22.84%); and the total soluble sugars (0.093%) were higher in the in vitro ginger plants.
Hence, the anatomical and biochemical variations observed in the different parts of the in vitro and in vivo ginger plants may be due to the differences in the growing conditions and the media used in the in vitro conditions.