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.

International audienceReclaiming degraded and contaminated soils with biochar amendments has become increasingly popular. Biochar, a fine-grained and porous biocarbon produced by the slow pyrolysis of biomass under oxygen limited conditions is foreseen as a possible solution to reduce metal(loid)s availability and phytotoxicity and simultaneously to improve the soil quality. Mining activities are one of the main concern generating potentially toxic elements (PTE) such as metal(loid)s-rich wastes and technosols. The effects of biochar addition (2% and 5%) on a former mine technosol characterized by high levels of PTE were investigated in laboratory during short-term experiments where technosols were potted and cultivated with dwarf beans (Phaseolus vulgaris L.) as indicator plants. Soil and soil pore water (SPW) physico-chemical properties were determined together with total dissolved concentrations of As, Sb and Pb in SPW sampled by Rhizons and available concentrations as measured by DGT (Diffusive Gradients in Thin-Films). Additionally indicator plant biomass and PTE concentrations in their organs (roots, stem and leaves) were determined. The results of the present study indicate that addition of 2 and 5% biochar to contaminated technosols increased soil and SPW pH, electrical conductivity (EC) and soil water content (SWC), decreased the labile concentration of Pb while increasing the As and Sb solubility. Indicator plants cultivated on biochar amended mine technosols showed a smaller biomass and higher PTE concentration levels in the various organs

a b s t r a c tGrafting can enhance the tolerance of vegetable crops to soilborne diseases. The aim of this study was to investigate whether different tomato scionerootstock 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 (0.12e0.37 cm) was significantly lower than that of plants grafted on sensitive "Cuore di Bue" (1.75e6.50 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.