# Nontoxic mesoporous silica nanoparticles protect Physcomitrium patens against salt stress

## TL;DR

Nontoxic silica nanoparticles help mosses resist salt stress by boosting stress-related genes and reducing harmful molecules.

## Contribution

This study reveals how mesoporous silica nanoparticles enhance salt tolerance in mosses through gene expression and ROS regulation.

## Key findings

- MSNs are nontoxic and increase salt tolerance in Physcomitrium patens.
- MSN-treated mosses show increased expression of stress-related genes like POX, L-AO, AOX, and CPK.
- MSNs reduce H2O2 and O2·− accumulation and modulate ROS homeostasis.

## Abstract

Mosses play a crucial role in environmental protection, ecological preservation, and horticulture. While the effects of nanomaterials on angiosperms have been widely studied, their impact on bryophytes remains underexplored. In this study, we investigated the effects of mesoporous silica nanoparticles (MSNs) and virus-like mesoporous silica nanoparticles (VMSNs) on the model moss species Physcomitrium patens (P. patens). Our results revealed that MSNs, with an average size of approximately 123 nm, are nontoxic to P. patens and enhance its salt tolerance. The expression of key genes involved in stress responses were significantly induced in MSN-treated plants under salt stress, including peroxidase (POX), L-ascorbate oxidase (L-AO), alternative oxidase (AOX), and calcium-dependent protein kinase (CPK). MSN treatment reduced the accumulation of H2O2 and O2·−, increased Ca2+ signaling, and modulated reactive oxygen species (ROS) homeostasis, collectively improving moss tolerance to salt stress. MSNs were observed on the cell surface, in intercellular space, and within the cytosol and vesicles. They were transported bidirectionally between rhizoids and apical leaves. This study provides novel insights into the distribution, transport, and functional mechanisms of MSNs in mosses, offering a valuable foundation for the application of nanomaterials in plant stress biology and ecological management of bryophytes.

The online version contains supplementary material available at 10.1007/s44154-025-00262-5.