An Investigation on Reduction Capability of Lead and Its Influence on Withanolides in in Vitro Shoots of Withania Somnifera (L.) Dunal

Green synthesis of nanoparticles using biological extracts/live organisms has been the best substitute for chemical/physical synthesizing methods. Live plants can convert simple metal ions into metal nanoparticles using their intrinsic metabolic processes. In addition, medicinal plants with a hyperaccumulation potential also have high reduction potential which can be utilized for in planta synthesis of metal nanoparticles. Lead (Pb), a non -essential heavy metal, is known to stimulate various biological processes in plants at higher concentrations. Therefore, a medicinal plant with a hyperaccumulation potential was selected to investigate its potential for in planta reduction of Pb. In the present study, in vitro grown 45 days old Withania somnifera (L.) Dunal shoots were exposed to lead acetate (PbAC 2 ) at varying concentrations (acute: 300-4800 m M; chronic: 50-800 m M) for 12-48 h and 4-12 days, respectively. It revealed that cultures grown in 800 m M PbAC 2 for 12 days of exposure (C5) recorded signi ficantly higher biomass (17.28 g) and increase in the divalent metal ions such as calcium from 1412 (control) to 1787 mg kg -1 (C5), potassium 21,109 (control) to 24,779 mg kg -1 (C5), and iron from 11 (control) to 82 mg kg -1 (C5), with lead (Pb) accumulation reaching up to 405 mg kg -1 (C5). Compared to the control shoots (0.783, 0.805 & 1.3 mg g-1), C5 shoots positively correlated with secondary metabolites namely withaferin A (3.14 mg g-1) and withanolide A (0.960 mg g-1) production and negatively with withanone (1.027 mg g-1). Also, C5 shoots had spherical shaped nanoparticles with a mean particle size of 25 10 nm which was then identi fied as lead nanoparticles (PbNPs). To our knowledge, the present study is the first of its kind where the in planta synthesis of PbNPs/PbONPs by in vitro shoot cultures of W. somnifera is reported along with accumulation of higher biomass and selective withanolides under Pb stress. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.