Aluminium, Iron and Silicon Subcellular Redistribution in Wheat Induced by Manganese Toxicity

Abstract

Acidic soils can promote the bioavailability of Al, Mn, and Fe to toxic levels, reducing crop growth and productivity. Symptoms of metal excess/deficit are dependent on the chemical composition of the soil solution and of plant tissues. In the present study, the concentration and subcellular distribution of Al, Mn, Fe, and Si (known to alleviate metal stress) were quantified through inductively coupled plasma mass spectrometry (ICP-MS) in roots and shoots of wheat grown in acidic soils with rising levels of Mn. In control acidic soil, wheat showed high concentrations of Al, Mn, and Fe. After Mn supplementation, bioavailable Al, Fe, and Si levels increased in the soil solution, but plant uptake ratio decreased. Root Mn levels increased, while those of Al, Fe, and Si decreased. Although elements were increasingly translocated to the shoot, root Al and Fe concentrations were 10-fold higher than those in the shoot. At the highest Mn concentration supplied, Al, Fe, and Si proportions increased in the organelles, while Mn proportion increased in the vacuole. High bioavailable Mn levels disrupt metal homeostasis in wheat grown in acidic soils, influencing element subcellular distribution. Symptoms of metal toxicity result from interactions between several elements, and therefore a comprehensive chemical analysis of soil solution and plant tissues contributes to a more accurate understanding of their uptake dynamics and their agronomic implications.