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Simple Summary: Hyperaccumulation is a particular trait that has evolved in a few plant species, conferring upon them the ability to accumulate large amounts of metal ions in above-ground tissues without showing symptoms of toxicity. Noccaea caerulescens is a model system to study metal hyperaccumulation and hypertolerance, since a significant number of populations exist, characterized by a wide variety of metal tolerance and accumulation. In this report, the serpentine population Monte Prinzera of N. caerulescens was treated with excess Ni, Zn and Co and subjected to Fe and Zn deficiency. Transcript analysis, correlated with tissue metal quantification, confirmed that this population was Ni, but not Zn, hypertolerant and hyperaccumulating. Moreover, excess Ni does not induce Fe deficiency as in Ni-sensitive species. Hyperaccumulation is a fascinating trait displayed by a few plant species able to accumulate large amounts of metal ions in above-ground tissues without symptoms of toxicity. Noccaea caerulescens is a recognized model system to study metal hyperaccumulation and hypertolerance. A N. caerulescens population naturally growing on a serpentine soil in the Italian Apennine Mountains, Monte Prinzera, was chosen for the study here reported. Plants were grown hydroponically and treated with different metals, in excess or limiting concentrations. Accumulated metals were quantified in shoots and roots by means of ICP-MS. By real-time PCR analysis, the expression of metal transporters and Fe deficiency-regulated genes was compared in the shoots and roots of treated plants. N. caerulescens Monte Prinzera confirmed its ability to hypertolerate and hyperaccumulate Ni but not Zn. Moreover, excess Ni does not induce Fe deficiency as in Ni-sensitive species and instead competes with Fe translocation rather than its uptake. [ABSTRACT FROM AUTHOR]

Plants are sessile organisms that must adapt to environmental conditions, such as soil characteristics, by adjusting their development during their entire life cycle. In case of low-distance seed dispersal, the new generations are challenged with the same abiotic stress encountered by the parents. Epigenetic modification is an effective option that allows plants to face an environmental constraint and to share the same adaptative strategy with their progeny through transgenerational inheritance. This is the topic of the presented review that reports the scientific progress, up to date, gained in unravelling the epigenetic response of plants to soil contamination by heavy metals and metalloids, collectively known as potentially toxic elements. The effect of the microbial community inhabiting the rhizosphere is also considered, as the evidence of a transgenerational transfer of the epigenetic status that contributes to the activation in plants of response mechanisms to soil pollution. [ABSTRACT FROM AUTHOR]

A more extensive study of the photochemistry of nitrophenyldihydropyridines was warranted because excitation may induce intramolecular transfer between two moieties held in a definite position. The photophysics of these molecules is of interest because of the short-path electron transfer between the two pi systems.

Research has been conducted on the pregna-1,4-diene-3,20-diones. The photochemistry of these diones which bear a hydroxy or alkoxy group at C (sub)17 has been explored and the results indicate that the irradiation causes the lumiketone rearrangement of this chromophore.

The photochemical behavior of four arylidenoxindole derivatives are examined in the context of the solid-state reactivity of (hetero)arylidenoxindoles. Data indicate that the photochemistry is quite structure-dependent and has a bearing on the mechanism of solid-state photodimerization.

Photolysis of N-methyl-, 4,5-dicyano- and 4,5-dicyanomethylphthalimides in the presence of benzylic donors leads to benzylation at either the carbonyl or cyano position. With N-methylphthalimides, the attack occurs at the carboximide position via electron transfer or radical cation cleavage. With the cyanides, there is also competitive, sometimes preferential, benzylation at the cyano position. This latter pathway happens when the spin and charge localizations are isolated from each other, a process that suggests intramolecular nucleophilic assistance when no steric bulk gets in the way.

In Arabidopsis thaliana (L.) Heynh., MYB59 transcription factor participates in regulating Ca homeostasis and signal transduction and is induced by Cd excess. To investigate its role in the facultative metallophyte Arabidopsis halleri ssp. halleri (L.) O'Kane and Al-Shehbaz, MYB59 expression was investigated under Cd treatment or Ca depletion in three populations belonging to distinct phylogeographic units (metallicolous PL22 and I16 and nonmetallicolous I29), and compared with the expression in A. thaliana. In control conditions, MYB59 transcription in A. thaliana and the non-metallicolous population I29 follow a comparable trend with higher expression in roots than shoots, whereas in metallicolous populations I16 and PL22 its expression is similar in roots and shoots, suggesting a convergent evolution associated with adaptation to metalliferous environments. After 6 h of Ca depletion, MYB59 transcript levels were very high in I16 and PL22 populations, indicating that the adaptation to metalliferous environments requires tightly regulated Ca homeostasis and signalling. Cd treatment caused variability in MYB59 expression. In I29, MYB59 expression, as in A. thaliana, is likely associated to stress response, whereas its modulation in the two metallicolous populations reflects the different strategies for Cd tolerance and accumulation. In conclusion, MYB59 regulation in A. halleri is part of the network linking mineral nutrition and Cd tolerance/accumulation. [ABSTRACT FROM AUTHOR]

Research has been conducted on pregna-1,4-dien-3,20-diones. The authors have investigated the photochemistry of these compounds, and the results have demonstrated the compounds are involved in ring A and isolated ketone cyclohexadienone moiety.

Abstract: The genetic engineering of plants to facilitate the reclamation of soils and waters contaminated with inorganic pollutants is a relatively new and evolving field, benefiting from the heterologous expression of genes that increase the capacity of plants to mobilize, stabilize and/or accumulate metals. The efficiency of phytoremediation relies on the mechanisms underlying metal accumulation and tolerance, such as metal uptake, translocation and detoxification. The transfer of genes involved in any of these processes into fast‐growing, high‐biomass crops may improve their reclamation potential. The successful phytoextraction of metals/metalloids and their accumulation in aerial organs have been achieved by expressing metal ligands or transporters, enzymes involved in sulfur metabolism, enzymes that alter the chemical form or redox state of metals/metalloids and even the components of primary metabolism. This review article considers the potential of genetic engineering as a strategy to improve the phytoremediation capacity of plants in the context of heavy metals and metalloids, using recent case studies to demonstrate the practical application of this approach in the field. [ABSTRACT FROM AUTHOR]

In the hyperaccumulator Arabidopsis halleri, the zinc (Zn) vacuolar transporter MTP1 is a key component of hypertolerance. Because protein sequences and functions are highly conserved between A. halleri and Arabidopsis thaliana, Zn tolerance in A. halleri may reflect the constitutively higher MTP1 expression compared with A. thaliana, based on copy number expansion and different cis regulation., Three MTP1 promoters were characterized in A. halleri ecotype I16. The comparison with the A. thaliana MTP1 promoter revealed different expression profiles correlated with specific cis-acting regulatory elements., The MTP1 5′ untranslated region, highly conserved among A. thaliana, Arabidopsis lyrata and A. halleri, contains a dimer of MYB-binding motifs in the A. halleri promoters absent in the A. thaliana and A. lyrata sequences. Site-directed mutagenesis of these motifs revealed their role for expression in trichomes. A. thaliana mtp1 transgenic lines expressing At MTP1 controlled by the native A. halleri promoter were more Zn-tolerant than lines carrying mutations on MYB-binding motifs. Differences in Zn tolerance were associated with different distribution of Zn among plant organs and in trichomes., The different cis-acting elements in the MTP1 promoters of A. halleri, particularly the MYB-binding sites, are probably involved in the evolution of Zn tolerance. [ABSTRACT FROM AUTHOR]