Selenium for Plants: Double Stress Resistance

         For the plant – double stress resistance.
        

      In the plant organism selenium affects resistance to various types of stress: oxidative stress caused by UV radiation, stress caused by herbicides, hypothermia, aging, salt stress, etc.

    The protective action of selenium under oxidative stress is manifested in the reduction of malondialdehyde content, free proline, increased chlorophyll stability, and biomass accumulation, as well as increased activity of glutathione peroxidase, dehydroascorbate reductase, and catalase.
Thus, the protective action of selenium in plants is associated with the formation of active centers of antioxidant system enzymes – superoxide dismutase, glycine reductase, glutathione peroxidase, catalase, ascorbate peroxidase, and dehydroascorbate reductase – and the increase in the pool of some low-molecular-weight antioxidants: carotenoids, ascorbic acid, glutathione.

    These properties indicate the involvement of selenium both in the first phase of biochemical adaptation (oxidation of foreign substances with the formation of organic oxides and peroxides) and in its second phase (binding and excretion of active metabolites).

     The selenium content in plants is 0.0001 mg% (by weight). Some plants are capable of concentrating selenium by extracting it from the soil, in particular, species of the genus Aster Aster L., Asteraceae.

    In case of selenium deficiency, plants experience stunted growth and flowering, lose resistance to changing environmental factors, especially to chilling and soil salinization, and often exhibit chlorosis, loss of turgor, and wilting.

    The plant that is a super-concentrator of selenium is Astragalus racemosus Pursh, Fabaceae (herb, ash content – 1–3%).

    Medicinal plants containing selenium:
• spirulina platensis Spirulina platensis (Nordst.) Geitl. (= Arthrospira platensis Gomont), Phormidiaceae, Cyanobacteria (microalgae, whole plant);
• Rhodiola rosea Rhodiola rosea L., Crassulaceae (rhizome with roots);
• Podophyllum peltatum L., Berberidaceae (rhizome with roots);
• Glycyrrhiza glabra L., Fabaceae (roots);
• Pastinaca sativa L., Apiaceae (roots, leaves);
• Phlomis tuberosa L., Lamiaceae (tubers, herb, content – 0.19 mg/kg);
• Astragalus dasyanthus Pall., Fabaceae (herb, content – up to 0.1% of dry weight);
• Panzeria lanata (L.) Bunge., Lamiaceae (herb, content – 0.43 mg/kg);
• Ephedra equisetina Bunge, Ephedraceae (herb);
• Equisetum arvense L., Equisetaceae (herb);
• Chelidonium majus L., Papaveraceae (herb, content – 0.07 mg/kg);
• Melilotus officinalis (L.) Pall., Fabaceae (herb, content – 0.08 mg/kg);
• species of Artemisia L., Asteraceae (herb, content – 0.11 mg/kg);
• Hedysarum gmelinii Ledeb., Fabaceae (herb, content – 0.24 mg/kg);
• Stipa pennata L., Poaceae (herb, content – 0.13 mg/kg);
• Thymus serpyllum L., Lamiaceae (herb, content – 0.16 mg/kg);
• Pentaphylloides fruticosa (L.) O. Schwarz., Rosaceae (herb, content – 0.06–0.25 mg/kg);
• Fragaria vesca L., Rosaceae (leaves, content – 0.04–0.06 mg/kg);
• Stanleya pinnata (Pursh) Britton, Brassicaceae (leaves);
• Digitalis lanata Ehrh., Scrophulariaceae (leaves);
• Catharanthus roseus (L.) G.Don, Apocynaceae (leaves);
• Aloe arborescens Mill., Asphodelaceae (leaves);
• Tussilago farfara L., Asteraceae (leaves);
• species of Eucalyptus L’Hér., Myrtaceae (leaves);
• Betula pendula Roth, Betulaceae (buds, leaves);
• Ribes nigrum L., Grossulariaceae (leaves);
• Bertholletia excelsa Humb. & Bonpl. (= Brazil nut), Lecythidaceae (fruits, content – up to 1.917 mg%);
• Happlopappus glutinosus Cas., Asteraceae (inflorescences);
• Chamomilla chamomilla (L.) Rydb., Asteraceae (inflorescences);
• species of Crataegus L., Rosaceae (fruits);
• species of Rosa L., Rosaceae (fruits);
• Schisandra chinensis (Turcz.) Baill., Schisandraceae (fruits);
• species of Juniperus L., Cupressaceae (fruits);
• Cucurbita pepo L., Cucurbitaceae (fruits, seeds);
• Anethum graveolens L., Apiaceae (fruits).