| Abstrakt: |
The interaction of selenium (Se) and melatonin in plants is unclear. The aim of this study was to investigate the effects of Se root application on melatonin synthesis in sweet cherry. Cultivar ‘Russia No.8’ was treated with Se6+(sodium selenate) or Se2−(selenomethionine). Parameters of plant antioxidant levels, growth parameters, and the synthesis enzyme activities and precursor contents of melatonin were measured. Results showed that the plant benefited more from Se6+than Se2−and were not exposed to Se stress by four low doses of Se6+(0, 0.2, 0.4, and 0.6 mg kg−1) treatments for 40 days. The trends of tryptophan hydroxylase (TPH), tryptamine-5-hydroxylas, and arylalkylamine N-acetyltransferase activities were similar, while tryptophan decarboxylase (TDC), serotonin-N-acetyltransferase (SNAT), caffeic acid-O-methyltransferase, and N-acetyl-5-hydroxytryptamine-O-methyltransferase (ASMT) activities were different in leaves and roots following different Se6+treatments. Tryptophan and 5-hydorxy tryptophan contents were not influenced by the Se6+dose. Tryptamine was not detected in leaves or roots, but the serotonin content was increased by Se6+treatment. The leaf content of N-acetyl-5-tryptophan was not influenced, but its synthesis was significantly induced in roots as the Se dose increased. Melatonin synthesis in leaves and roots was increased only following treatment with 96 mg Se6+. The leaf Se and melatonin content showed no significant linear relationship in the ‘Russia No.8’ cultivar. Treatment with Se2−increased the enzyme levels of TDC, TPH, SNAT, and ASMT more significantly than Se6+. Overall, lower doses of Se6+did not significantly induce melatonin synthesis, but the relationship between melatonin and Se2−merits further attention. |
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