# Foliar-Applied Selenium–Zinc Nanocomposite Drives Synergistic Effects on Se/Zn Accumulation in Brassica chinensis L

## TL;DR

A new nanocomposite of selenium and zinc applied to plants boosts nutrient levels in edible parts, improving both crop yield and nutritional value.

## Contribution

A foliar-applied selenium–zinc nanocomposite is developed for synergistic co-biofortification in Brassica chinensis.

## Key findings

- Nano-ZSe increased shoot biomass by 28.4% and elevated Se and Zn concentrations in edible tissues.
- Nano-ZSe reprogrammed the redox system and enhanced foliar nutrient uptake through stomatal opening.
- Nano-ZSe improved soil properties and rhizosphere microbial diversity while increasing economic returns.

## Abstract

Micronutrient malnutrition persists as a global health burden, while conventional biofortification approaches suffer from low efficiency and environmental trade-offs. This study aimed to develop and evaluate a foliar-applied selenium–zinc nanocomposite (Nano-ZSe, a mixture of zinc ionic fertilizer and nano selenium) for synergistic Se/Zn co-biofortification in Brassica chinensis L., using a controlled pot experiment that integrated physiological, metabolic, molecular, and rhizosphere analyses. Application of Nano-ZSe at 0.18 mg·kg−1 (Based on soil weight) not only increased shoot biomass by 28.4% but also elevated Se and Zn concentrations in edible tissues by 7.00- and 1.66-fold (within the safe limits established for human consumption), respectively, compared to the control. Mechanistically, Nano-ZSe reprogrammed the ascorbate-glutathione redox system and redirected carbon flux through the tricarboxylic acid cycle, suppressing acetyl-CoA biosynthesis and reducing abscisic acid accumulation. This metabolic rewiring promoted stomatal opening, thereby enhancing foliar nutrient uptake. Simultaneously, Nano-ZSe triggered the coordinated upregulation of BcSultr1;1 (a sulfate/selenium transporter) and BcZIP4 (a Zn2+ transporter), enabling synchronized translocation and the tissue-level co-accumulation of Se and Zn. Beyond plant physiology, Nano-ZSe improved soil physicochemical properties, enriched rhizosphere microbial diversity, and increased crop yield and economic returns. Collectively, this work demonstrates that nano-enabled dual-nutrient delivery systems can bridge nutritional and agronomic objectives through integrated physiological, molecular, and rhizosphere-mediated mechanisms, offering a scalable and environmentally sustainable pathway toward functional food production and the mitigation of hidden hunger.