Nanoporous Quercetin-Loaded Silicon-Stabilized Hybrid Lipid Nanoparticles Alleviate Salt Stress in Tomato Plants

Abstract

The search for more effective methods to alleviate the negative effects of exogenous stresses in plants has inspired nanotechnologies. It is in this context that the use of formulations containing nanoporous silicon-stabilized hybrid lipid nanoparticles acting as delivery systems of the flavonoid quercetin was investigated here. These formulations, referred to as phyto-couriers, proved their efficacy in protecting the important crop model Solanum lycopersicum "Micro-Tom" against salinity. Two phyto-courier formulations, GS1 and GS3, functionalized with 25 mg of quercetin and differing in the presence of trehalose were applied to salt-stressed tomato by foliar spraying. The shape and ordered structure of the palisade cells was completely compromised under salinity; however, the phyto-couriers preserved their elongated shape under abiotic stress. From a molecular point of view, some stress-responsive genes tended to decrease in expression in stressed leaves treated with the phytocouriers. Shotgun proteomics confirmed the nano-biostimulant nature of the formulations: several proteins involved in cytoprotection against oxidative stress were more abundant in control leaves treated with the phyto-couriers. Proteins involved in chromatin remodeling were also more abundant in control leaves treated with the trehalose-containing GS3 formulation, a finding indicating a priming effect. Overall, the formulations showed promising results to enhance abiotic stress tolerance in a crop model through the mitigation of stress symptoms. The results presented proof of the stress-relieving properties of the silicon-stabilized hybrid lipid nanoparticles and are a proof-of-concept for the use of the phyto-courier nanotechnology in horticultural applications.

A Study on the Use of the Phyto-Courier Technology in Tobacco Leaves Infected by Agrobacterium tumefaciens

“…In a previous study, the phyto-courier functionalised with quercetin (2.5 or 25 mg) was also sprayed several times on the leaves of plants (textile hemp and tomato) and shown to protect against salinity by acting as a nano-biostimulant [ 12 , 13 ]. Once injected or sprayed, quercetin is delivered into the leaf parenchyma, where it is progressively released, increasing its intracellular abundance before stress occurs, thus acting as a biostimulant.…”

“…In a previous study, the external supply of quercetin in the growth medium could protect thale cress, tobacco, and duckweed against the harmful effects of reactive oxygen species (ROS) [ 15 ]. Plants treated with the phyto-courier functionalised with 2.5 mg and 25 mg of quercetin showed decreased symptoms under salt stress, as manifested by the decreased expression of genes related to stress [ 12 ] and by proteomics [ 13 ].…”

“…Suspensions of the sshLNPs functionalised with 25 mg of quercetin (GS3 formulation) and respective controls (buffer alone, B, and free quercetin, Q) [ 13 ] were prepared prior to the experiment. Polyvinyl alcohol (PVA) bags of GS3 or Q were accurately weighed and solubilised according to their weight in the appropriate volume of dispersant, to normalise the content.…”

“…Nanoparticles (NPs) can be used to alleviate stress symptoms in plants subjected to exogenous constraints, utilised to enhance plant nutrition and protection or to deliver a bio-active compound effectively into plant cells [ 10 , 11 ]. In that context, it was previously reported that the formulation based on silicon (Si)-stabilised hybrid lipid nanoparticles (sshLNPs) functionalised with quercetin (referred to as phyto-courier) is a promising technology to alleviate the negative effects of stresses in plants [ 12 , 13 ]. Quercetin is a secondary plant metabolite that belongs to the group of flavonoids and is synthesised via the phenylpropanoid pathway.…”

“…Previously, publications on textile hemp [ 12 ] and tomato [ 13 ] focused on evaluating the ameliorative effects of quercetin-loaded sshLNPs in plants subjected to salinity. Here, the effect of the GS3 phyto-courier functionalised with 25 mg of quercetin was investigated in tobacco plants subjected to a biotic stress.…”