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Halophytes have superior capacity to withstand soil salinity and are appropriate resources to study the mechanism of salt tolerance which can be harnessed to develop crops to withstand salinity. In this communication, we report the effect of salinity (200 mM NaCl) and elevated carbon dioxide (CO2) treatments in tandem, on select halophytes that have different photosynthetic pathways: C3 and C4. The plants were raised in ambient (380 ppm) and enriched (500 ppm) concentrations of CO2 using a mini-FACE facility. Total chlorophyll content, total soluble sugar concentration, lipid peroxidation level and electrolyte leakage were measured from fresh leaf samples collected at different time points. The results show a positive effect for elevated CO2 concentration on salt tolerance in both C3 and C4 plants, and indicate that halophytes may benefit from rising atmospheric CO2 concentration. The results also suggest that C4 halophytes may benefit from the rising atmospheric CO2 concentration than C3 halophytes. [ABSTRACT FROM AUTHOR]

Soil salinity is a major abiotic stress that affects global agricultural productivity. Exploring the mechanisms that halophytes employ to thrive and flourish under saline environments is essential to increase the salt tolerance in sensitive crop species. Of the three halophytes used in this study Salicornia brachiata and Suaeda maritima belong to the same family Chenopodiaceae, while Sesuvium portulacastrum, a mangrove-associated halophyte, belongs to the family Aizoaceae. Assuming that halophytes of same family share similar salt tolerance mechanisms, we generated a suppression subtractive hybridization (SSH1) cDNA library from salt-treated leaf tissues of S. brachiata as tester and that of S. maritima as driver to identify salt-responsive genes unique to S. brachiata. To elucidate the difference in salt-tolerance mechanisms, and to identify salt-tolerance mechanisms amongst different families of halophytes, SSH2 library was generated from salt-treated leaf tissue of S. brachiata as tester and that of S. portulacastrum as driver. Totally, 87 and 49 EST clones representing unique genes were obtained from SSH1 and SSH2 libraries, respectively. Examination of the expression patterns of 17 (SSH1) and 15 (SSH2) differentially expressed genes using semi-quantitative RT-PCR confirmed up-regulation of these genes in shoots in response to salt treatment and elevated CO2 condition, but to a different extent. This study has provided insights into the molecular responses of S. brachiata to salt stress and elevated CO2 conditions. [ABSTRACT FROM AUTHOR]

Nanomaterials-mediated contamination (including the highly reactive metal oxides ZnO nanoparticles) is becoming one of the most concerning issues worldwide. In this study, the toxic effects of two chemical species of Zn (ZnO nanoparticles and bulk ZnSO 4 ) were investigated in bean plants, following either foliar or soil application, at concentrations from 250 to 2000 mg L -1 using biochemical assays, proteomics and metabolomics. The accumulation of Zn in plant tissues depended on the application type, zinc chemical form and concentration, in turn triggering distinctive morphological, physiological, and redox responses. Bean plants were more sensitive to the foliar than to the soil application, and high concentrations of ZnO NP and bulk ZnSO 4 determined the highest plant growth inhibition and stress symptoms. However, low dosages of ZnSO 4 induced a slight plant growth promotion and better physiological and antioxidative response. Low concentration of Zn leaded to increased activity of stress-related proteins and secondary metabolites with antioxidant capacity, while increasing concentration reached the exhausted phase of the plant stress response, reducing the antioxidant defense system. Such high concentrations increased lipids peroxidation, protein degradation and membranes integrity. Oxidative damage occurred at high concentrations of both chemical species of Zn. Foliar spraying impaired photosynthetic efficiency, while soil applications (especially ZnSO 4 ) elicited antioxidant metabolites and proteins, and impaired chloroplast-related proteins involved in the electron transport chain and ATP production. Taken together, the results highlighted distinctive and nanoparticles-related toxic effects of ZnO in bean, compared to ionic forms of Zn., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)