Differential iron management in monocotyledon and dicotyledon plants from the Río Tinto basin.

The study of plants adapted to an extreme environment with a high concentration of iron such as Río Tinto allowed the study of important elements for the development and control of plant growth including their localization, management, and storage. The absorption, transport, and accumulation of iron were studied in different species of dicotyledons (Sarcocornia pruinosa, Salicornia patula, Arthrocnemum macrostachyum, and Halogeton sativus of the Chenopodiaceae family) and monocotyledons (Imperata cylindrica, Cynodon dactylon, and Panicum repens from the Poaceae family), all obtained from the Río Tinto banks in different sample collection campaigns. The results clearly show that phytoferritin is not observed in the chloroplast of monocotyledons, an important difference from what is observed in dicotyledons. The presence of plastids with a high concentration of iron in the sieve tubes of monocotyledons strongly suggests their possible role in the transport and accumulation of iron in these plants.

Formation of biomineral iron oxides compounds in a Fe hyperaccumulator plant: Imperata cylindrica (L.) P. Beauv.

We report a detailed work of composition and location of naturally formed iron biominerals in plant cells tissues grown in iron rich environments as Imperata cylindrica. This perennial grass grows on the Tinto River banks (Iberian Pyritic Belt) in an extreme acidic ecosystem (pH∼2.3) with high concentration of dissolved iron, sulphate and heavy metals. Iron biominerals were found at the cellular level in tissues of root, stem and leaf both in collected and laboratory-cultivated plants. Iron accumulated in this plant as a mix of iron compounds (mainly as jarosite, ferrihydrite, hematite and spinel phases) was characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), Mössbauer spectroscopy (MS), magnetometry (SQUID), electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX; TEM-EDX; HRSTEM). A low fraction of phosphorous was detected in this iron hyperaccumulator plant. Root and rhizomes tissues present a high proportion of ferromagnetic iron oxide compounds. Iron oxides-rich zones are localized in electron dense intra and inter-cellular aggregates that appear as dark deposits covering the inner membrane and organelles of the cell. This study aims to contribute to a better understanding of the mechanisms of accumulation, transport, distribution of iron in Imperata cylindrica.

Nickel localization on tissues of hyperaccumulator species of phyllanthus L. (Euphorbiaceae) from ultramafic areas of Cuba.

Two species of perennial Phyllanthus (Euphorbiaceae) (Phyllanthus orbicularis and Phyllanthus discolor, both endemic to ultramafic areas of Cuba, and their natural hybrid, Phyllanthus xpallidus) were selected for metal localization microanalysis. Different plant tissues were analyzed by X-ray fluorescence, inductively coupled plasma-atomic emission spectroscopy, and scanning electron microscopy coupled with an energy-dispersive X-ray probe. All of the studied taxa are nickel (Ni) hyperaccumulators and significant concentrations of this element were found in different leaf and stem tissues. The highest Ni content was found in the laticifer tubes, whereas leaf epidermis Ni content resulted to be much more relevant in terms of total metal storage. Calcium and magnesium were found more evenly distributed in leaf and stem tissues.