Application of NanoSIMS and isotopic labeling to analyze the spatial distribution of the plant iron chelator nicotianamine

TL;DR

This study uses a high-resolution imaging technique to track a plant compound that helps transport iron, revealing its role in iron distribution.

Contribution

The novel use of NanoSIMS and isotopic labeling to directly visualize nicotianamine distribution in plants.

Findings

15N-NA signals were concentrated in tissue surrounding xylem vessels.

Fe accumulation was observed in both wild type and NA-free mutant plants in these regions.

Abstract

Nicotianamine (NA) is an iron (Fe) chelator responsible for the Fe translocation and transport within the plant body and cells. NA is also hypothesized to be involved in Fe homeostasis as a Fe deficiency signal transducer in plants. This study visualized the distribution of stable isotope-labeled NA in plants by high-resolution secondary ion mass spectrometry (NanoSIMS) to better understand the mechanisms of NA-mediated Fe translocation, transport, and Fe homeostasis. Stable isotope-labeled NA (15N-NA) was produced by heterologous expression of an NA synthase in yeast and supplied to wild type (WT) tomato plants and the NA-free mutant chloronerva (chln). NanoSIMS showed that 15N-NA signals were concentrated in tissue surrounding xylem vessels, where Fe accumulated in both WT and chln. Our results show that NanoSIMS is a powerful tool for investigating NA localization directly in plants.

Figures