ABSTRACT
Rice is one of the most widely cultivated crops worldwide; however, it is not amenable to genetic manipulations, owing to its poor response to tissue culture and regeneration in vitro. To improve its response to tissue culture, we evaluated the influence of biosynthesized silver nanoparticles on callus induction, regeneration and rhizogenesis in Indica rice cv. IR64. Silver nanoparticles were biosynthesized by using silver nitrate and Parthenium hysterophorus plant extract, and were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, Transmission electron microscopy and X-ray diffraction. The biosynthesized silver nanoparticles (PHAgNPs), when supplemented in tissue culture medium, promoted callus induction frequency, callus regeneration and rhizogenesis at concentrations of 10 mg l -1, 5 mg l-1 and 10 mg l-1, respectively. Further examination of the endogenous hormonal levels in regenerating calli revealed that AgNPs enhanced regeneration by alleviating abscisic acid and ethylene levels in the plant tissue. The stimulatory influence eliciting the regeneration response was found to be optimal with the supplementation of 5 mg l-1 PHAgNPs in the regeneration medium; the malondialdehyde, proline and hydrogen peroxide levels were also lower than those in the control, thus suggesting improved antioxidant status. Our results indicated that biosynthesized PHAgNPs may have the potential to positively influence tissue culture of recalcitrant varieties.
Subject(s)
Hormesis/drug effects , Metal Nanoparticles/chemistry , Oryza/chemistry , Silver/pharmacology , Gene Expression Regulation, Plant/drug effects , Hydrogen Peroxide/metabolism , Malondialdehyde/metabolism , Oryza/drug effects , Oryza/genetics , Oryza/ultrastructure , Plant Roots/drug effects , Proline/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Regeneration/drug effectsABSTRACT
Hybanthus enneaspermus is an ethanobotanical plant extensively used in Indian traditional medicine. Quick and efficient in vitro mass propagation of this plant species was established for commercial utilization from leaf and node explants using various concentrations and combinations of plant growth regulators and polyamines. The maximum number of multiple shoots per leaf explant (40 shoots) was achieved on MS medium supplemented with 20 mg/l spermidine in combination with 4 mg/l BA+1.5 mg/l IAA after 8 weeks of culture. The elongated shoots were rooted (16 roots/shoot) on MS medium with the best concentration of IBA (1.5 mg/l) and in combination with 20 mg/l putrescine after 5 weeks of culture. The plants were successfully acclimatized (98 %) in the sand: soil: vermiculite mixture (1:1:1 v/v/v) in the greenhouse. An increased antioxidant activity was recorded in vitro regenerated shoots when compared to in vitro-induced roots. L-Dopa content was recorded higher in leaves (8.31 mg/g DW) followed by stem (6.22 mg/g DW) and root (3.22 mg/g DW) of leaf-derived plants than the field-grown parent plant after 5 weeks. By adopting this protocol, the regenerated-plants could be used for drug production and pharmacology work with as an alternative to field-grown plants.
