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Quinoa ( Chenopodium quinoa Willd), an ancient Andean seed crop, exhibits exceptional nutritional properties and resistance to abiotic stress. The species' tolerance to heavy metals has, however, not yet been investigated nor its ability to take up and translocate chromium (Cr). This study aimed to investigate the metabolic adjustments occurring upon exposure of quinoa to several concentrations (0.01–5 mM) of CrCl 3 . Young hydroponically grown plants were used to evaluate Cr uptake, growth, oxidative stress, and other biochemical parameters three and/or seven days after treatment. Leaves accumulated the lowest amounts of Cr, while roots and stems accumulated the most at low and at high metal concentrations, respectively. Fresh weight and photosynthetic pigments were reduced only by the higher Cr(III) doses. Substantially increased lipid peroxidation, hydrogen peroxide, and proline levels were observed only with 5 mM Cr(III). Except for a significant decrease at day 7 with 5 mM Cr(III), total polyphenols and flavonoids maintained control levels in Cr(III)-treated plants, whereas antioxidant activity increased in a dose-dependent manner. Maximum polyamine accumulation was observed in 1 mM CrCl 3 -treated plants. Even though α- and γ-tocopherols also showed enhanced levels only with the 1 mM concentration, tyrosine aminotransferase (TAT, EC 2.6.1.5) activity increased under Cr(III) treatment in a dose- and time-dependent manner. Taken together, results suggest that polyamines, tocopherols, and TAT activity could contribute to tolerance to 1 mM Cr(III), but not to the highest concentration that, instead, generated oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract: The effects of a high concentration of zinc on two registered clones of poplar (Populus alba Villafranca and Populus nigra Jean Pourtet), inoculated or not with two arbuscular mycorrhizal fungi (Glomus mosseae or Glomus intraradices) before transplanting them into polluted soil, were investigated, with special regard to the extent of root colonization by the fungi, plant growth, metal accumulation in the different plant organs, and leaf polyamine concentration. Zinc accumulation was lower in Jean Pourtet than in Villafranca poplars, and it was mainly translocated to the leaves; the metal inhibited mycorrhizal colonization, compromised plant growth, and, in Villafranca, altered the putrescine profile in the leaves. Most of these effects were reversed or reduced in plants pre-inoculated with G. mosseae. Results indicate that poplars are suitable for phytoremediation purposes, confirming that mycorrhizal fungi can be useful for phytoremediation, and underscore the importance of appropriate combinations of plant genotypes and fungal symbionts. [Copyright &y& Elsevier]

Many areas of the world are affected simultaneously by salinity and heavy metal pollution. Halophytes are considered as useful candidates in remediation of such soils due to their ability to withstand both osmotic stress and ion toxicity deriving from high salt concentrations. Quinoa (Chenopodium quinoa Willd) is a halophyte with a high resistance to abiotic stresses (drought, salinity, frost), but its capacity to cope with heavy metals has not yet been fully investigated. In this pot experiment, we investigated phytoextraction capacity, effects on nutrient levels (P and Fe), and changes in gene expression in response to application of Cr(III) in quinoa plants grown on saline or non-saline soil. Plants were exposed for three weeks to 500 mg kg−1 soil of Cr(NO 3) 3 ·9H 2 O either in the presence or absence of 150 mM NaCl. Results show that plants were able tolerate this soil concentration of Cr(III); the metal was mainly accumulated in roots where it reached the highest concentration (ca. 2.6 mg g−1 DW) in the presence of NaCl. On saline soil, foliar Na concentration was significantly reduced by Cr(III). Phosphorus translocation to leaves was reduced in the presence of Cr(III), while Fe accumulation was enhanced by treatment with NaCl alone. A real-time RT-qPCR analysis was conducted on genes encoding for sulfate, iron, and phosphate transporters, a phytochelatin, a metallothionein, glutathione synthetase, a dehydrin, Hsp70, and enzymes responsible for the biosynthesis of proline (P5CS), glycine betaine (BADH), tocopherols (TAT), and phenolic compounds (PAL). Cr(III), and especially Cr(III)+NaCl, affected transcript levels of most of the investigated genes, indicating that tolerance to Cr is associated with changes in phosphorus and sulfur allocation, and activation of stress-protective molecules. Moderately saline conditions, in most cases, enhanced this response, suggesting that the halophytism of quinoa could contribute to prime the plants to respond to chromium stress. • Salinity and heavy metal pollution are one of the world's major environmental concerns. • Quinoa is a halophytic crop and highly tolerant to multiple stresses. • Plants did not show any toxicity symptoms in the presence of Cr with or without NaCl. • Cr and/or NaCl severely affected the uptake of nutrients. • The presence of Cr with or without NaCl modified the expression of several genes. [ABSTRACT FROM AUTHOR]