Trigonella foenum-graecum morphophysiological and phytochemical processes controlling iron uptake and translocation

Context. Iron (Fe) is considered as a major cause of rural Tunisian soil contamination. Developing strategies for the cultivation of accumulator plants with permissible iron (Fe) concentrations is an urgent challenge. Aims. In this study, the effects of FeSO4 concentration (0, 50, 500 and 1000 mg L−1) on fenugreek morpho-biochemical parameters were investigated. Methods. The use of fenugreek as a phytoremediation strategy to control not only the uptake of Fe but also its safe consumption after treatments was evaluated. Key results. Results showed that elevated Fe concentrations did not affect the germination rate, but, rather, decreased the radicle length and amylase activity. The elemental analysis showed that Fe uptake was higher in shoots than in roots, but lower in harvested seeds. The translocation factor was higher than 1, suggesting a safe use of fenugreek as an accumulator. Moreover, the increase in Fe concentrations reduced the chlorophyll content and enhanced the production of lipid peroxidation, hydrogen peroxide and superoxide dismutase more frequently on fenugreek shoots than on their roots. In turn, the maximum concentrations of flavonoids and phenols were recorded under the Fe concentration of 50 mg L−1. High-performance liquid chromatography analysis showed that the gallic and syringic acids were the major phenols produced under Fe stress in shoots and that 50 mg L−1 of added Fe concentration induced their elevation. However, the quercetin was detected only in roots and was reduced under the increasing Fe concentrations. Conclusions. These results showed that fenugreek is an accumulator plant with admissible concentrations of Fe accumulation, which deploys multiple mechanisms to adapt to Fe stress.