Effect of phycochemical coated silver nanocomplexes as novel growth-stimulating compounds for plant regeneration of Alternanthera sessilis L.

In the present study, phycochemical-loaded silver nanocomplexes (GFAgNPs) were fabricated by using Gracilaria foliifera seaweed extracts as capping agents on silver ions. The growth-stimulating properties of the GFAgNPs were evaluated by using in vitro plant regeneration from axillary nodal explants of Alternanthera sesselis. Explants were sterilized and placed on Murashige and Skoog (MS) medium augmented with various concentrations of GFAgNPs (0.5-3.0 mg L-1), 6-benzyl amino purine (BAP), and kinetin (KIN) (0.5-5.0 mg L-1) for initiation of shoot buds. One hundred percent shoot bud initiation with highest number of shoot buds (112.5 shoots explant(-1)) was observed on MS medium supplemented with 2.0 mg L-1 GFAgNPs, while shoot bud initiation was 85.3 % with 3.0 mg L-1 BAP. To enhance the percentage of multiple shoot bud proliferation, the mini-shoot buds were subcultured onto MS medium fortified with different doses of GFAgNPs (0.5-3.0 mg L-1), BAP, and KIN (0.5-4.0 mg L-1) in combination with 50 mg L-1 adenine sulfate (AdS). Of the three growth-promoting compounds tested, 100 % of multiple shoot bud regeneration with twofold increased shoots (153.6 shoots culture(-1)) was obtained on MS medium containing 2.5 mg L-1 GEAgNPs and 50 mg L-1 AdS combination, followed by 3.0 mg L-1 BAP and 50 mg L-1 AdS combination. Elongated shoots were excised from shoot clumps and cultured on half-strength MS medium without auxin but fortified with different concentrations of alpha-naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA) (0.1-0.5 mg L-1) for rooting. IBA at 0.5 mg L-1 was found to be the best dose for 100 % rooting with 13.5 roots shoot(-1). Rooted plantlets were successfully transplanted into plastic cups containing sand and soil mixture, and the acclimatized plantlets were subsequently established in field conditions. The genetic fidelity of in vitro regenerated plants was determined by using random amplified polymorphic DNA (RAPD) analysis. In vitro regenerated plantlets were true to type in nature. The use of phycochemical-coated silver nanocomplex as novel growth-regulating substances was identified as an alternate to commercial cytokinins for large-scale production of genetically uniform plantlets in tissue culture for industrial applications.