Acetylcholinesterase-Inhibition and Antibacterial Activity of Mondia whitei Adventitious Roots and Ex vitro-Grown Somatic Embryogenic-Biomass

Indirect organogenesis-mediated high frequency conversion of non-embryonic synthetic seeds, essential oil profiling and antibacterial activity in genetically stable plants of Patchouli

Patchouli is a prized tropical medicinal herb with broad-spectrum therapeutic importance. The present research work describes development of an efficient callus-mediated plant regeneration protocol along with associated germplasm portability system (via alginate-encapsulation). Using 1.5 mg/l α-naphthalene acetic acid (NAA) and 1.0 mg/l 2, 4-dichlorophenoxy acetic acid (2, 4-D), highly proliferative friable calli were produced that subsequently underwent organogenesis in combinatorial cytokinin treatment to yield multiple shoot clusters. The highest frequency of shoot formation was achieved using 1.5 mg/l NAA with 1.5 mg/l 6-benzylaminopurine (BAP) in Murashige and Skoog (MS) medium. In vitro-derived shoot tips were encapsulated with 3% sodium alginate and 100 mM CaCl2 solution. The encapsulated beads were germinated in MS media with various concentrations of polyamines, where the highest regeneration frequency was observed with 1.5 mg/l spermidine. The regenerated shoots were rooted in basal MS medium and were successfully acclimatized with 96% survival rate. Genetic homogeneity amongst the regenerated plantlets was validated using Start Codon Targeted polymorphism (SCoT) and CAAT box-derived polymorphism (CBDP) ascertaining a high degree of clonal fidelity. The essential oil (EO) profiling of the donor plant and the in vitro-derived plantlets revealed identical composition. Furthermore, the antibacterial activities of various tissue extracts and extracted EOs were evaluated against the opportunistic pathogens viz. Klebsiella pneumoniae (MTCC 109), Salmonella typhii (MTCC 733), Micrococcus luteus (MTCC 2470) and Staphylococcus aureus (MTCC 96). The minimum inhibitory concentration (MIC) ranged from 0.31 to 5.0 mg/ml and 2.5 to 5.0 mg/ml against Gram-positive and Gram-negative bacteria, respectively. Eventually, the present research provides a holistic insight into the rapid regeneration of quality planting material as well as pharmacological bioprospection of patchouli along with the scope of further qualitative improvement via genetic transformation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03302-3.

Adventitious root cultures of Decalepis salicifolia for the production of 2-hydroxy-4-methoxybenzaldehyde, a vanillin isomer flavor metabolite

Decalepis salicifolia (Bedd. ex. Hook.f.) Venter is a potential natural source of the vanillin isomer, 2-hydroxy-4-methoxybenzaldehyde (2H4MB), an aromatic compound. However, the utilization of the plant is hindered especially due to its critically endangered status and the root-specific accumulation of the compound. The use of in vitro culture techniques offers a sustainable means for the production of valuable metabolites. In this study, an efficient system was established for the production of 2H4MB in the adventitious root cultures of D. salicifolia. Leaf explants of in vitro grown plants produced on an average 4.33 ± 2.07 number of roots with root initiation frequency of 95.69 ± 3.74% in woody plant medium supplemented with 0.5 mg/L α-naphthalene acetic acid (NAA) and 1.0 mg/L kinetin (Kn). The adventitious root biomass accumulation of 10.61 ± 0.89 g fresh weight (FW) was obtained in woody plant liquid media containing 0.5 mg/L NAA and 0.3 mg/L indole-3-butyric acid (IBA) in 60 days of inoculation. Field-grown plants of the same age produced 0.30 ± 0.02 g FW, which was 35-fold lower than the adventitious root culture. The total production of 2H4MB in the same growth period was 4.9-fold higher in adventitious root culture (139.54 μg) as compared to field-grown plants (28.62 μg). Furthermore, sucrose concentration of 2% was favorable for biomass accumulation, whereas 5% was favorable for 2H4MB production. On the other hand, media pH 5.0 was suitable for biomass production and pH 7.0 was best suited for accumulation of 2H4MB. The adventitious roots also showed stable production of biomass and 2H4MB over 2 years. The established adventitious root culture system is suitable for further large-scale production of 2H4MB for flavor and fragrance industrial applications. KEY POINTS: • Biomass accumulation was higher in adventitious root cultures than in field-grown plants. • Manipulation of sucrose concentration and media pH led to increased 2H4MB production. • Adventitious roots showed stable biomass and 2H4MB production over 2 years.