A novel method for the histolocalization of Al and Pb in root tissues, tested in Typha domingensis Pers. grown in iron mining tailings

Abstract The objective of this work was to test a new method for Al and Pb histolocalization using Chrome Azurol S (CAS) and Pyrogallol Red (PGR), respectively, using roots from Typha domingensis Pers. plants grown in iron mining tailings. For both CAS and PGR, we tested two solvents (distilled water pH 6.7 and 100 mM phosphate buffer pH 5.0), two concentrations (0.1% and 0.5%, m V − 1 ), and three reaction times (1, 5, and 10 min). We tested CAS and PGR histolocalization of Al and Pb in T. domingensis plants, which were grown for 180 days in flooded iron mining tailings containing 2385.6 mg Al Kg − 1 and 6.8 mg Pb Kg − 1 ; as a control, we used plants from a natural population from an unpolluted location. T. domingensis roots grown in iron mining tailings accumulated 1384 mg Kg − 1 of Al and 18 mg Pb Kg − 1 . CAS and PGR promoted no reaction in tissues from unpolluted roots; however, CAS and PGR reacted with root tissues from polluted roots under all tested conditions. CAS staining evidenced cytosolic Al present in purple and red vesicles in epidermal and cortical root cells from polluted roots. PGR application in polluted roots highlighted the presence of cytosolic Pb in pale-pink and red vesicles in the epidermis and cortex. Both CAS and PGR produced a reddish hue in the cell walls from the vascular cylinder, indicating the presence of Al and Pb. Thus, CAS and PGR can be used for Al and Pb histolocalization in polluted root tissues.