Silver nanoparticles elicited in vitro callus cultures for accumulation of biomass and secondary metabolites in Caralluma tuberculata

Figures & data

Figure 1. Synthesis and characterization of AgNPs. (A) 40 nm silver nanoparticles, (B) representative spectra of silver nanoparticle dispersion, 10–200 nm, (C) TEM of 40 nm silver nanoparticles. Representative TEM, batch-to-batch variation may be expected.

Figure 2. Pictorial presentation of the in vitro cultures in Caralluma tuberculata (A). Explant inoculated on culture media (B). Callus initiation from explant (C). Callus induction on MS media with 2,4-D (0.5 mg/L) + BA (3 mg/L) (D). Sub-culturing of induced callus (E). Callus proliferated on MS media with 2,4-D (0.5 mg/L) + BA (3 mg/L) (F). Callus proliferated on MS media with 2,4-D (0.5 mg/L) + BA (3 mg/L) + AgNPs 30 μg/L (G). Callus proliferated on MS media with 2,4-D (0.5 mg/L) + BA (3 mg/L) + AgNPs 60 μg/L (H). Callus proliferated on MS media with 2,4-D (0.5 mg/L) + BA (3 mg/L) + AgNPs 90 μg/L (I).

Table 1. Effect of AgNPs either alone or in combination with 2,4-D + BA on callus proliferation in Caralluma tuberculata.

Treatments	Fresh weight (g/l)	Dry weight (g/l)	Water content (%)
MS0	0.0463^a	0.0047^a	89.25^ab
AgNPs 30 μg/l	0.048^a	0.0060^a	86.88^a
AgNPs 60 μg/l	0.051^a	0.0050^a	89.95^abc
AgNPs 90 μg/l	0.106^a	0.0113^a	88.82^a
2,4-D (0.5 mg/l) + BA (3.0 mg/l)	0.143^a	0.0140^a	90.00^abc
AgNPs 30 μg/l+ 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	0.132^a	0.0120^a	90.83^abc
AgNPs 60 μg/L + 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	0.780^b	0.0517^b	93.43^bc
AgNPs 90 μg/l + 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	0.730^b	0.0457^b	93.71^c

Data were collected from three replicates. Means with same alphabets are not significantly different in accordance with DMRT, at p ≤ .05.

Table 2. Effect of AgNPs either alone or in combination with 2,4-D + BA on callus morphology in Caralluma tuberculata.

Treatments	Callus colour	Callus nature
MS0	Yellow brown	Fragile
AgNPs 30 μg/l	Yellow brown	Fragile
AgNPs 60 μg/l	Yellow greenish	Fragile
AgNPs 90 μg/l	Yellow greenish	Semi-compact
2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	Yellow Greenish	Semi-compact
AgNPs 30 μg/l + 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	Yellow Greenish	Semi-compact
AgNPs 60 μg/l + 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	Greenish	Compact
AgNPs 90 μg/l + 2, 4-D (0.5 mg/l) + BA (3.0 mg/l)	Greenish	Compact

Figure 3. Assessment of the non-enzymatic antioxidant elements in the callus cultures of Caralluma tuberculata established in response to different concentration of AgNPs treatments. Data represent the mean values of triplicates with ± standard error. Columns data with different letter/s differ significantly at p ≤ .05 (A): total phenolic content (TPC), (B) total flavonoid content (TFC), (C) phenylalanine ammonia lyase (PAL) activity, (D) free radical scavenging activity.

Figure 4. Assessment of the enzymatic antioxidant elements in the callus cultures of Caralluma tuberculata established in response to different concentration of AgNPs treatments. Data represent the mean values of triplicates with ± standard error. Columns data with different letter/s differ significantly at p ≤ .05 (A): superoxide dismutase (SOD) activit, B: peroxidase (POD) activity, C: catalase (CAT) activity, D: ascorbate peroxidase (APx) activity.

Figure 5. The proposed mechanism of action of AgNPs on cell signaling and secondary metabolism in cell cultures through elucidation of MAPK pathway.

Data availability

All the required data, which is related to current study, are embedded in this manuscript.