Induction of Cell Protective Reactions of Triticum aestivum and Secale cereale to the Effect of High Temperatures by Melatonin

Currently, melatonin (N-acetyl-5-methoxytryptamine) is considered as a multifunctional bioregulator not only in mammals but also in plants. The aim of this work was to study the effect of melatonin on the resistance of seedlings of wheat (Triticum aestivum L., Dosconala variety) and rye (Secale cereale L., Pamyat' Khudoyerka variety) to high temperature and the functioning of key cellular protection systems (antioxidant and osmoprotective). Rye seedlings were different from wheat seedlings by higher heat resistance, which was manifested in less inhibition of the growth after a 6-h heating at 44 degrees C and less manifestation of the oxidative stress effects. The treatment of wheat seeds with melatonin in concentrations of 20-100 mu M significantly decreased the inhibition of the shoot and root growth caused by the effect of a high temperature. The rye seedlings were less affected by melatonin, reducing only the inhibition of the shoot growth. The treatment with melatonin prevented the development of the oxidative stress caused by the effect of high temperature, which was manifested in a decrease in the indices of superoxide radical generation, the content of hydrogen peroxide and malondialdehyde in the shoots of wheat and rye seedlings. The treatment of caryopses of both cereal species with melatonin caused an increase in the catalase activity against the background of the heat stress as well as contributed to the stabilization of peroxidase activity under stress conditions in wheat and caused its increase in rye. In addition, the treatment of caryopses with melatonin caused an increase in the content of soluble carbohydrates under stress conditions but did not affect significantly the content of proline in the shoots of seedlings of both species. In general, a less noticeable effect of melatonin treatment on the functioning of the protective systems in rye was noted. A decrease in the oxidative damage to the cells, an increase in the activity of antioxidant enzymes, and an increase in the accumulation of soluble carbohydrates are the key effects of melatonin under stress conditions.

Automated summary

Melatonin is a multifunctional bioregulator in both mammals and plants. This study investigated the effect of melatonin on the resistance of wheat and rye seedlings to high temperature and the functioning of cellular protection systems. The results showed that melatonin treatment reduced the inhibition of growth caused by high temperature in wheat seedlings, while it had a smaller effect on rye seedlings. Melatonin treatment also prevented oxidative stress in both wheat and rye seedlings under high temperature conditions.