Respiratory potential and Se compounds in pea (Pisum sativum L.) plants grown from Se-enriched seeds.

Selenium (Se) has been proved to be an essential element for humans and animals. However, less is known about its effects on plants. Pea plants were treated foliarly once (OT) and twice (TT) with Se solution during their flowering period. Seeds obtained from these plants contained 383 and 743 ng Se g(-1), respectively, and, together with control seeds from untreated plants (UT) containing 21 ng Se g(-1), were sown in soil in a greenhouse. Se content and its chemical form in young plants were studied, and its impact on plant respiratory potential, measured as terminal electron transport system (ETS) activity, determined. ETS activity was highest in young pea leaves with the highest Se content. Higher ETS activity possibly reflected increased glutathione peroxidase (GSH-Px) activity in mitochondria. The Se content of leaves and stems of plants grown from control seeds was similar to that in the seed, being around 40 ng Se g(-1). Se concentration in leaves of young plants grown from OT and TT seeds was 605%, and 1340% higher, respectively, than the control, and in their stems 355%, and 680% higher, respectively. The ratio of Se concentrations in OT and TT seeds was the same as in the leaves and stems in the young plants grown from them. SeMet was the major Se compound in Se-rich pea seeds and leaves, comprising 49% and 67% of the total Se content in OT and TT seeds, respectively, and 85% and 79% in the corresponding leaves.

Selenium species determination in selenium-enriched pumpkin (Cucurbita pepo L.) seeds by HPLC-UV-HG-AFS.

Pumpkins were treated by spraying the leaves in the flowering period with a water solution containing 1.5 mg Se per liter in the form of Na2SeO4. The average total selenium content of seeds was found to be 0.19 microg g(-1) in nontreated pumpkins and 1.1 microg g(-1) in exposed ones. For speciation analysis, enzymatic hydrolysis with different amounts of Protease XIV was carried out. Under optimal conditions of enzymatic hydrolysis, 90% of the total selenium was found in soluble forms. Separation of species was performed using HPLC on anion and cation exchange columns and for detection UVHG-AFS was applied. In enzymatic hydrolysis extracts, the main fraction of selenium was bound as selenomethionine (SeMet), representing on average of 81 +/- 8% of the total Se content in the sample.