Effect of Nanoparticles on Callusing and Induction of Somaclonal Variations

Nanoparticles exhibit diverse impacts on callus induction, proliferation, and the induction of somaclonal diversity within plant tissue culture systems. Their size ranges between one and one hundred nanometers, characterized by unique chemical and physical traits such as high reactivity and surface area to volume ratio, which enable them to penetrate easily through cellular membranes. They are classified as metal/metal oxide NPs (Ag, Au, ZnO, TiO2), carbon-based NPs (CNTs, GO), polymeric NPs, and biogenic or green-synthesized materials. In plant tissue culture, nanoparticles enhance callus induction and proliferation by controlling the manipulation of auxin and cytokinin to facilitate the presence of optimal hormone cofactors while working against their inhibitors, such as the inhibition of ethylene biosynthesis by silver nanoparticles. At proper concentrations, NPs induced moderate reactive oxygen species (ROS) priming, where molecules acted as a signal for dedifferentiation and cell-cycle activation, improving the callus morphogenesis and regenerative potential. NPs also function as inducers of somaclonal variation by acting on genomic stability and cellular processes. High concentration lead to genotoxicity, DNA damage, and structural chromosomal changes. NPs-induced somaclonal variations have been used in plant breeding to speed up conventional and mutation-based breeding for stress tolerance or yield improvement. It is important that nanoparticles should be physicochemically characterized at the highest level and systematically monitored using molecular markers, cytogenetic studies, and higher-end methods to ensure clonal fidelity and lower environmental risk due to the lack of standard protocols and regulatory directions.