Phytoremediation Potential and Differential Chromium (Cr) Accumulation and Gene Expression in Brassica juncea Varieties for Contaminated Soils in Turkey

Several agricultural areas in the Anatolian Plateau of Turkey are contaminated with chromium due to mining and leather tanning activities, posing a serious threat to both safe farming and human health. Cleaning polluted soils for reuse in agriculture is a vital and primary goal of this research. This study aimed to identify suitable Brassica juncea varieties for phytoremediation of metal-contaminated soils in Turkey, with the goal of promoting safe farming practices. Six varieties—Early Raya, Sindh Raya, S-9, Ganj Sarhen, JS-13, and THB-8—developed by the Agricultural Institute of Pakistan for drought and salt tolerance, were tested for metal tolerance at different Cr levels (0–1000 µM). Physiological parameters were recorded, and the contents of Cr, Ca, Fe, Mg, and K in plant tissues were quantified using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Additionally, the gene expression of several enzymes induced by ROS was examined using RT-qPCR. Early raya and Sindh raya under Cr stress showed different expression patterns of these genes, highlighting significant genotypic differences in chromium uptake, nutrient balance, and molecular responses. Our results classified the varieties into three different groups: Early raya and THB-81 as accumulators, Sindh raya, and S-9 as excluders, and Ganj sarhen, and JS13, as intermediate Cr accumulators. This study offers important insights into genotype-specific detoxification strategies. It lays the fundamental groundwork for future breeding programs and phytoremediation research aimed not only at reducing Cr contamination and promoting safe agriculture in contaminated soils in Turkey and other countries facing similar pollution issues.