14 Pags.- 7 Figs., Mercury (Hg) is one of the most hazardous pollutants released by humans and is of global environmental concern. Mercury causes oxidative stress and strong cellular damages in plants, which can be attenuated by the biosynthesis of thiol-rich peptides (biothiols), including glutathione (GSH) and phytochelatins (PCs). We analysed Hg tolerance and speciation in five Arabidopsis thaliana genotypes, the wild-type Col-0, three knockdown γ-glutamylcysteine synthetase (γECS) mutants and a knockout PC synthase (PCS) mutant. Mercury-PC complexes were detected in roots by HPLC-ESI-TOFMS, with its abundance being limited in γECS mutants. Analysis of Hg-biothiol complexes in the xylem sap revealed that HgPC2 occurs in wild-type Col-0 Arabidopsis, suggesting that Hg could be translocated associated with thiol-rich metabolites. Twenty genes involved in sulphur assimilation, GSH and PCs synthesis were differentially expressed in roots and shoots, implying a complex regulation, possibly involving post-translational mechanisms independent of GSH cellular levels. In summary, the present study describes the importance of biothiol metabolism and adequate GSH levels in Hg tolerance and identifies for the first time Hg-PC complexes in the xylem sap. This finding supports the notion that Hg-biothiol complexes could contribute to Hg mobilisation within plants., Work supported by the Spanish State Research Agency (AEI) co-financed with the European Regional Development Fund (ERDF) (projects AGL2014-53771-R and AGL2017-87591-R to LEH and AGL2016-75226-R to AAF and JA; AEI/ERDF, UE)., Peer reviewed

Microplastics have been found in all environmental compartments investigated so far, even reaching remote areas. However, their presence in Antarctic freshwaters has not been yet reported. Here, we investigated the occurrence of microplastics in a stream from an Antarctic Specially Protected Area (Byers Peninsula, Livingston Island - ASPA No. 126), which is subject to stringent environmental protection measures as a result of which it is considered a pristine international reference site for inland waters research. Our results showed the presence of three types of microplastics in a freshwater seasonal stream, namely four polyester fibers, one black and three transparent; two acrylic fibers, one transparent and one red; and two transparent polytetrafluoroethylene films. The length and width of these fibers and films were in the 400–3546 μm (average 1118 μm), and 10–1026 μm (average 199 μm) ranges respectively. The concentration of MP was 0.95 items/1000 m with estimated variability in the 0.47–1.43 items/1000 m range. This is the first report of the presence of microplastics in Antarctic freshwater with the uniqueness that it is an Antarctic Specially Protected Area, meaning that plastic pollution reached even the most remote and pristine environments in the planet., This research was funded by the Spanish Ministry of Economy and Competitiveness (CTM2016-74927-C2-1/2-R, CTM2016-79741R, AGL2014- 53771-R and AGL2017-87591-R); CLIMARCTIC (PCIN2016-001) funded by the Spanish State Research Agency in the frame of the 2015–2016 BiodivERsA COFUND call for research proposals. We thank all members of the EnviroPlaNet Network Thematic Network of Micro- and Nanoplastics in the Environment (RED2018-102345-T; Ministry of Science, Innovation and Universities).

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/., Root-knot nematodes (RKNs) are obligate endoparasites that feed on their host plants to complete its life cycle, representing a major threat to agriculture and economy worldwide. The development of new management strategies becomes essential as effective chemical nematicides are progressively being restricted. Hence, we analysed grape pomace-derived biochars, pyrolysed at 350 °C (BC350) and 700 °C (BC700), focusing on their potential for RKN control. The thermal treatment of grape pomace caused an increase in the concentration of carbon and plant macro- and micronutrients, which were largely present in a water-soluble form. Synchrotron radiation-based Fourier transform infrared microspectroscopy data showed a general loss of carboxylic functional groups during pyrolysis, partially contributing to the alkalinisation of both biochars, mostly in BC700. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis revealed a highly porous structure filled with different crystals composed of elements such as K, Ca, Mg, P, Si or Al, which could be a suitable environment for the growth of microorganisms. Biochar-derived aqueous extracts showed phytotoxicity to tomato seedlings at high concentrations, and disappeared upon dilution, but no toxic effect was observed on the nematode’s infective stage. However, the infective and reproductive traits of a Meloidogyne javanica population in tomato were significantly reduced (i.e. egg masses and eggs per plant) in washed-biochar-treated soil in pots (0.75%; BC350W). Therefore, the large amount of grape waste generated after wine production can be transformed into a valuable product such as biochar, effective for RKNs control, thus reducing the waste management problem and contributing to a circular economy., This work was supported by the Spanish Government (PID2019-105924RB-I00 MCIN/AEI/10.13039/501100011033; RED2018-102407-T) to CE, and (AGL2014-53771-R; AGL2017-87591-R) to LEH, and by the Castilla-La Mancha Government (SBPLY/17/180501/000287 and SBPLY/21/180501/000033) to CE. AM-G was recipient of a PhD grant from Fundación Tatiana Pérez de Guzmán el Bueno. EU FEDER funds complemented all the grants., Peer reviewed