Preliminary Observations On The Metal Tolerance And Resilience Capacity Of Helichrysum Italicum (Roth) G. Don Growing On Mine Soils

Abstract

Wild specimens of Helichrysum italicum, with their soil clod, were gathered from sites with different contamination levels by heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in the abandoned Niccioleta mine (Tuscany, Italy). We examined the effects of heavy metals (HM) on the morphology of H. italicum growing on mine soils, with the following objectives: to determine the fate of HM within the soilplant system; to highlight morphological modifications at anatomical and cytological level; to ascertain the plant tolerance to heavy metals, and their resilience capacity. Plants appeared macroscopically not affected by toxic signals. Light microscopy and TEM observations of leaves show a clear difference in the cell organization of not-contaminated and contaminated samples. Trichomes of the polluted plants present a completely different morphology in comparison to nonpolluted ones, with a stalk of 3-4 cells and a large secreting apical cell, a palisade parenchyma less organized, and a reduction of leaf thickness. A gradual restoration of cell organization suggests that somewhat resilience occurred in plants. The resilience capacity points to H. italicum as an useful species in remediation projects.

Keywords

• heavy metals
• mine soils
• plant morphology
• Helichrysum italicum
• ultrastructure