Arabidopsis thaliana zinc accumulation in leaf trichomes is correlated with zinc concentration in leaves

Abstract

Zinc (Zn) is a key micronutrient. In humans, Zn deficiency is a common nutritional disorder, and most people acquire dietary Zn from eating plants. In plants, Zn deficiency can decrease plant growth and yield. Understanding Zn homeostasis in plants can improve agriculture and human health. While root Zn transporters in plat model species have been characterized in detail, comparatively little is known about shoot processes controlling Zn concentrations and spatial distribution. Previous work showed that Zn hyperaccumulator species such as Arabidopsis halleri accumulate Zn and other metals in leaf trichomes. The model species Arabidopsis thaliana is a non-accumulating plant, and to date there is no systematic study regarding Zn accumulation in A. thaliana trichomes. Here, we used Synchrotron X-Ray Fluorescence mapping to show that Zn accumulates at the base of trichomes of A. thaliana, as had seen previously for hyperaccumulators. Using transgenic and natural accessions of A. thaliana that vary in bulk leaf Zn concentration, we demonstrated that higher leaf Zn increases total Zn found at the base of trichome cells. Furthermore, our data suggests that Zn accumulates in the trichome apoplast, likely associated with the cell wall. Our data indicates that Zn accumulation in trichomes is a function of the Zn status of the plant, and provides the basis for future studies on a genetically tractable plant species aiming at understanding the molecular steps involved in Zn spatial distribution in leaves.