Iron Status Affects the Zinc Accumulation in the Biomass Plant Szarvasi-1

Abstract

Thinopyrum obtusiflorum (syn. Elymus elongatus subsp. ponticus) cv. Szarvasi-1 (Poaceae, Triticeae) is a biomass plant with significant tolerance to certain metals. To reveal its accumulation capacity, we investigated its Zn uptake and tolerance in a wide range: 0.2 to 1000 µM Zn concentration. The root and shoot weight, shoot length, shoot water content and stomatal conductance proved to be only sensitive to the highest applied Zn concentrations, whereas the concentration of malondialdehyde increased only at the application of 1 mM Zn in the leaves. Although physiological status proved to be hardy against Zn exposure, shoot Zn content significantly increased in parallel with the applied Zn treatment, reaching the highest Zn concentration at 1.9 mg g−1 dry weight. The concentration of K, Mg and P considerably decreased in the shoot at the highest Zn exposures, where that of K and P also correlated with a decrease in water content. Although the majority of microelements remained unaffected, Mn decreased in the root and Fe content had a negative correlation with Zn both in the shoot and root. In turn, the application of excessive EDTA maintained a proper Fe supply for the plants but lowered Zn accumulation both in roots and shoots. Thus, the Fe-Zn competition for Fe chelating phytosiderophores and/or for root uptake transporters fundamentally affects the Zn accumulation properties of Szarvasi-1. Indeed, the considerable Zn tolerance of Szarvasi-1 has a high potential in Zn accumulation.