Cd, Pb, and Zn mobility and (bio)availability in contaminated soils from a former smelting site amended with biochar.

Biochar is a potential candidate for the remediation of metal(loid)-contaminated soils. However, the mechanisms of contaminant-biochar retention and release depend on the amount of soil contaminants and physicochemical characteristics, as well as the durability of the biochar contaminant complex, which may be related to the pyrolysis process parameters. The objective of the present study was to evaluate, in a former contaminated smelting site, the impact of two doses of wood biochar (2 and 5% w/w) on metal immobilization and/or phytoavailability and their effectiveness in promoting plant growth in mesocosm experiments. Different soil mixtures were investigated. The main physicochemical parameters and the Cd, Pb, and Zn contents were determined in soil and in soil pore water. Additionally, the growth, dry weight, and metal concentrations were analyzed in the different dwarf bean plant (Phaseolus vulgaris L.) organs tested. Results showed that the addition of biochar at two doses (2 and 5%) improved soil conditions by increasing soil pH, electrical conductivity, and water holding capacity. Furthermore, the application of biochar (5%) to metal-contaminated soil reduced Cd, Pb, and Zn mobility and availability, and hence their accumulation in the different P. vulgaris L. organs. In conclusion, the data clearly demonstrated that biochar application can be effectively used for Cd, Pb, and Zn immobilization, thereby reducing their bioavailability and phytotoxicity.

Effect of short-term cadmium stress on Populus nigra L. detached leaves.

Pollution by toxic metals, accumulating into soils as result of human activities, is a worldwide major concern in industrial countries. Plants exhibit different degrees of tolerance to heavy metals, as a consequence of their ability to exclude or accumulate them in particular tissues, organs or sub-cellular compartments. Molecular information about cellular processes affected by heavy metals is still largely incomplete. As a fast-growing, highly tolerant perennial plant species, poplar has become a model for environmental stress response investigations. To study the short-term effects of cadmium accumulation in leaves, we analyzed photosystem II (PSII) quantum yield, hydrogen peroxide (H2O2) generation, hormone levels variation, as well as proteome profile alteration of 50µM CdSO4 vacuum-infiltrated poplar (Populus nigra L.) detached leaves. Cadmium management brought about an early and sustained production of hydrogen peroxide, an increase of abscisic acid, ethylene and gibberellins content, as well as a decrease in cytokinins and auxin levels, whereas photosynthetic electron transport was unaffected. Proteomic analysis revealed that twenty-one proteins were differentially induced in cadmium-treated leaves. Identification of fifteen polypeptides allowed to ascertain that most of them were involved in stress response while the remaining ones were involved in photosynthetic carbon metabolism and energy production.

Tomato susceptibility to Fusarium crown and root rot: effect of grafting combination and proteomic analysis of tolerance expression in the rootstock.

Grafting can enhance the tolerance of vegetable crops to soilborne diseases. The aim of this study was to investigate whether different tomato scion-rootstock combinations may affect the plant susceptibility to Fusarium oxysporum f. sp. radicis-lycopersici (FORL), the causal agent of crown and root rot. A proteomic approach was used to investigate whenever the protein repertoire of the rootstock can be modified by FORL infection, in relation to cultivar susceptibility/tolerance to the disease. To this purpose, plants of tomato hybrids with different vigor, "Costoluto Genovese" (less vigorous) and "Kadima" (more vigorous), were grafted onto "Cuore di Bue" and "Natalia" hybrids, sensitive and tolerant versus FORL infections, respectively. Disease symptoms, plant biomasses, and protein expression patterns were evaluated 45 days after FORL inoculation. The extent of vascular discoloration caused by FORL in tomato plants grafted on "Natalia" rootstock (0.12-0.37 cm) was significantly lower than that of plants grafted on sensitive "Cuore di Bue" (1.75-6.50 cm). FORL symptoms significantly differed between "Costoluto Genovese" and "Kadima" scions only when grafted on sensitive rootstock. Shoot FW of non-inoculated "Kadima"/"Cuore di Bue" combination was 35% lower than "Kadima"/"Natalia", whereas no difference was manifested in inoculated plants. Shoot FW of inoculated "Costoluto Genovese"/"Cuore di Bue" combination was decreased of 39%, whereas that of "Costoluto Genovese"/"Natalia" of 11%, compared to control plants. Proteomic results showed a higher representation of proteins associated with pathogen infection in the tolerant rootstock, compared to the sensitive one, meaning a direct involvement of plant defence mechanisms in the tomato response to the pathogen challenge.

Proteomic analysis of temperature stress-responsive proteins in Arabidopsis thaliana rosette leaves.

Plants, as sessile organisms, are continuously exposed to temperature changes in the environment. Low and high temperature stresses have a great impact on agricultural productivity, since they significantly alter plant metabolism and physiology. Plant response to temperature stress is a quantitative character, being influenced by the degree of stress, time of exposure, as well as plant adaptation ability; it involves profound cellular changes at the proteomic level. We describe here the quantitative variations of the protein repertoire of Arabidopsis thaliana rosette leaves after exposing seedlings to either short-term cold or heat temperature stress. A proteomic approach, based on two-dimensional electrophoresis and MALDI-TOF peptide mass fingerprinting and/or nanoLC-ESI-LIT-MS/MS experiments, was used for this purpose. The comparison of the resulting proteomic maps highlighted proteins showing quantitative variations induced by temperature treatments. Thirty-eight protein spots exhibited significant quantitative changes under at least one stress condition. Identified, differentially-represented proteins belong to two main broad functional groups, namely energy production/carbon metabolism and response to abiotic and oxidative stresses. The role of the identified proteins is discussed here in relation to plant adaptation to cold or heat stresses. Our results suggest a significant overlapping of the responses to opposite temperature extremes.

N-acyldopamines control striatal input terminals via novel ligand-gated cation channels.

Endogenous analogues of capsaicin, N-acyldopamines, were previously identified from striatal extracts, but the putative presynaptic role of their receptor, the TRPV(1)R (formerly: vanilloid or capsaicin receptor) in the caudate-putamen is unclear. We found that the endogenous TRPV(1)R agonists, N-arachidonoyldopamine (NADA) and oleoyldopamine (OLDA) with EC(50) values in the nanomolar range, as well as the synthetic TRPV(1)R activator 2-aminoethoxydiphenylborane (2APB), and palmytoyldopamine (PALDA, another endogenous N-acyldopamine inactive at the TRPV(1)R), but not capsaicin or other endogenous and synthetic cannabinoids, triggered a rapid Ca(2+) entry with the concomitant stimulation of glutamate and dopamine release. These effects persisted in the TRPV(1)R null-mutant mice, and were insensitive to antagonists of common ionotropic receptors, to several TRPV(1)R antagonists and to the absence of K(+). Furthermore, these N-acyldopamine receptors in glutamatergic and dopaminergic terminals are different based on their different sensitivity to anandamide, capsazepine and Gd(3+) at nanomolar concentrations. Altogether, novel ion channels instead of the TRPV(1)R mediate the presynaptic action of N-acyldopamines in the striatum of adult rodents.