Effect of salinity on Brassica rapa var. toria (BRSRT) under selenium defence: A trial to assess the protective role of selenium | UČINEK SLANOSTI NA VRSTO Brassica rapa var. toria (BRSRT) OB PRISOTNOSTI SELENA: POSKUS OVREDNOTENJA ZAŠČITNE VLOGE SELENA

anglais. The present study assesses the role of selenium, an antioxidant in salt-stressed plants. A hydroponic trial of sodium selenate (Na2SeO4) on the growth, oxidative stress and antioxidant protection system of Brassica rapa var. toria (BRSRT) plant was studied. 40 µmol and 100 µmol of Na2SeO4 were hydroponically applied to BRSRT roots with 50 mmol and 100 mmol sodium chloride (NaCl) for 12 days. Plant growth, biomass production and photosynthetic pigments at 100 mmol salt stress was inhibited while oxidative stress indicators, for example, hydrogen peroxide and lipid peroxidation were stimulated. Supplementation of 40 µmol Na2SeO4 with 50 mmol and 100 mmol NaCl improved growth, photosynthetic pigments and acted as an antioxidant by inhibiting lipid peroxidation and increasing superoxide dismutase, ascorbate peroxidase, catalase, glutathione peroxidase, glutathione reductase activities. The in-gel assays also showed enhanced activities of these enzymes. At 100 µmol concentration, selenium under salt stress, repressed growth and expression of antioxidant enzymes and stimulated oxidative stress with enhanced glutathione peroxidase activity. Under consolidated stress treatment, an addition of 40 µmol Na2SeO4 was the most effective for both NaCl concentrations. The finding reveals that the optimal selenium supplementation presents a promising potential for use in conditions of relatively high levels of NaCl stress for BRSRT seedlings.

slovène. V raziskavi je ovrednotena vloga selena kot antioksidanta pri rastlini v slanostnem stresu. Vpliv natrijevega selenata (Na2SeO4) na rast, oksidacijski stres in antioksidacijsko zaščito vrste Brassica rapa var. toria (BRSRT) je bil preučevan v hidroponskem poskusu. 40 µmol in 100 µmol Na2SeO4 je bilo 12 dni hidroponsko dodajano koreninam rastline, ki so rastle v 50 mmol in 100 mmol raztopini natrijevega klorida (NaCl). Rast rastlin, produkcija biomase in vsebnost fotosinteznih pigmentov so bili zavrti pri rastlinah pod 100 mmol solnim stresom, aktivirani pa so bili indikatorji oksidativnega stresa kot sta vodikov peroksid in peroksidacija lipidov. Dodajanje 40 µmol Na2SeO4 pri 50 mmol in 100 mmol NaCl je izboljšalo rast, vsebnost fotosinteznih barvil in delovalo kot antioksidant z inhibicijo peroksidacije lipidov in povečanjem aktivnosti superoksid dismutase, askorbat peroksidaze, katalaze, glutation peroksidaze in glutation reduktaze. Povečano aktivnost teh encimov je pokazala tudi njihova gelska anliza. Selen je pri koncentraciji 100 µmol v razmerah solnega stresa zavrl rast in tvorbo antioksidativnih encimov in vzpobudil oksidacijski stres s povečano aktivnostjo glutation peroksidaze. V danih stresnih obravnavanjih je bilo dodajanje 40 µmol Na2SeO4 najbolj učinkovito pri obeh koncentracijah NaCl. Rezultati kažejo, da predstavlja optimalno dodajanje selena dober obet za njegovo uporabo v razmerah relativno velikega NaCl stresa pri sadikah obravnavane rastline.