# Transcriptomic and physiological analyses revealed nicotianamine enhances wheat tolerance to excess manganese

## TL;DR

The study shows that nicotianamine helps wheat tolerate excess manganese by boosting its production and regulating metal balance.

## Contribution

The novel contribution is identifying specific nicotianamine-related genes that enhance wheat's tolerance to excess manganese.

## Key findings

- Mn-tolerant wheat genotypes show increased nicotianamine (NA) production and gene expression.
- Exogenous NA application reduces Mn uptake and restores essential cation homeostasis in wheat.
- Candidate genes TaNAS, TaNAAT, TaYSL2, and TaYSL6 are linked to Mn tolerance in wheat.

## Abstract

Manganese (Mn) is an essential plant micronutrient but toxic at supra-optimal concentrations. Although nicotianamine (NA) biosynthesis is metal inducible, its specific role in Mn detoxification in wheat remains poorly characterized. Integrated transcriptomic and physiological analyses of Mn-tolerant (ET8, Carazinho) and Mn-sensitive (ES8, Egret) wheat near-isogenic lines and their parental cultivars under excess Mn revealed pronounced upregulation of genes encoding nicotianamine synthase (TaNAS), nicotianamine aminotransferase (TaNAAT), and putative Mn-NA transporters (TaYSL2, TaYSL6) in tolerant genotypes. This transcriptional response correlated with elevated NA accumulation in roots under Mn stress. Exogenous NA application enhanced Mn tolerance in hydroponically grown seedlings in a concentration-dependent manner, accompanied by reduced tissue Mn accumulation, and maintained homeostasis of essential cations (Ca, Mg, Fe, Zn, Cu) in both roots and shoots. Our findings demonstrate that NA biosynthesis and transport contribute to Mn tolerance by modulating Mn partitioning and metal ion homeostasis. We further propose candidate genes (TaNAS, TaNAAT, TaYSL2, TaYSL6) as potential targets for breeding Mn-tolerant wheat.

•Mn tolerance relies on nicotianamine (NA) biosynthesis gene induction in wheat•Mn-tolerant wheat genotypes elevate NA production for superior Mn sequestration•Exogenous NA alleviates toxicity by reducing Mn uptake and restoring homeostasis

Mn tolerance relies on nicotianamine (NA) biosynthesis gene induction in wheat

Mn-tolerant wheat genotypes elevate NA production for superior Mn sequestration

Exogenous NA alleviates toxicity by reducing Mn uptake and restoring homeostasis

Plant Biology; Agricultural science; Agricultural soil science; Agricultural plant products.