Journal of Plant Process and Function

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Selenium is an essential element in some organisms, but high concentrations can leading to toxicity in plant. Methyl jasmonate hormone plays an important role in defence processes. In this research, the effect of Methyl jasmonate (Me JA) and sodium selenate (Na2SeO4 ) on growth, content of pigments, phenol, anthocyanin and proline in tomato plants were studied. The seeds to germinate in petri dishes were sterilized. After germination, the seedlings were transferred to pots containing moist sand. The plants with second leaves were treated with of 0, 30 and 60 µM Na2SeO4 and 0, 50 and 100 µM Me JA. After 20 days, plants were harvested and certain assays carried out. The plants were treated with Me JA and Na2SeO4 grew significantly compared with other treatments. In all of treatments chlorophyll a and b contents decreased, however, carotenoid contents in 60 µM Na2SeO4 increased. With addition of MeJA to culture solutions containing sodium selenate, the plants showed increase in amount of phenol and anthocyanin in comparison with plants treated with sodium selenate. MeJA had no significant effect on proline content, but sodium selenate with and without MeJA increased proline content. The results showed that interaction of Me JA and Na2SeO4 reduced the harmful effects of sodium selenate.

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Secondary metabolites with low molecular weight and high economic, pharmaceutical and industrial values play an important role in protecting plants against biotic and abiotic stresses. Astragalus is a medicinal herb, rich in secondary metabolites. Selenium (Se) is an essential element for humans, animals, many bacteria, as well as a beneficial element for plants. The plants response to selenium is depending on their species and the Se supply concentration. In the present study, calli were established from the seeds of Astragalus verus and suspension cultures were established from the calli. The cells were treated with different concentrations of sodium selenate (0, 0.5, 2.5, 12.5, and 62.5 μM) for 1 week at their logarithmic growth phase (based on growth curve). Cell growth and viability significantly decreased by selenium at concentrations higher 2.5 μM. In comparison with control group, significant increases in Abscisic acid and Salicylic acid were observed at higher Se concentrations, whereas methyl jasmonate significantly increased at lower Se supply. At 62.5 μM Se supply the contents of alkaloids, phlobaphene, steroidal and triterpenoid saponins, and tannin respectively increased by 5.1, 1.51, 1.62, 1.75, and 2.04 times of control. The results provides a practical method for remarkable stimulation of natural compounds of Astargalus by Se.

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Garlic (Allium sativum L.) is susceptible to phosphorus (P) deficiency and because of coarse root system with low branching rate, this species is highly dependent on mycorrhizal symbiosis. As a beneficial element for higher plants, selenium (Se) improves nutritional and pharmaceutical quality of this species. In this research, the effect of Se (at 0, 20 and 80 µg L^–1 of substrate as Na₂SeO₄) was investigated in garlic plants grown under adequate (2 mM) and low P (without P supply for six weeks) in the absence or presence of arbuscular mycorrhizal fungus (AMF), Diversispora versiformis in perlite as substrate and irrigated with Hoagland nutrient solution for six weeks. Results showed that, P deficiency caused reduction of shoot growth and leaf photosynthesis while AMF inoculation results in the improvement of growth, photosynthesis and sugars content. Selenium augmented the effect of AMF inoculation leading to the highest dry biomass, photosynthesis and sugars content under the combination of both treatments irrespective the P supply level. The root activity of acid phosphatase (APase) was not affected by low P or +AMF as single treatments, while Se alone or in combination with low P and +AMF significantly increased the APase activity. The optimum Se concentration on the biomass, root colonization rate, photosynthesis and APase activity was 80 µg L^–1. This is the first report on the synergistic effect of Se on AMF symbiosis on the adaptive response of plants to P deficiency.