Determination of the effects of serotoni̇n on tomato under salinitt and drought stress in terms of certain physiological and moleculer parameters

In this study, it was aimed to determine the effects of drought and salt stress by using tomato seedlings and to reveal the effects of serotonin hormone application against drought and salt stress. For this purpose, hormone applications were applied by adding 5 μM serotonin hydrochloride into Hoagland solution from seed sowing and the application continued during stress applications. As a result of all these applications, stem/root fresh-dry weight, stem-root length, stem-root water content amounts, proline, MDA, ion leakage and relative water content amounts, and antioxidant enzyme gene such as CAT, SOD, GR, APX and stress-related gene such as ACS2, P5CS expressions were analysed. As a result of the study, salt and drought stress decreased stem length and stem-root dry weight compared to control. Serotonin administration increased root tissue length, but had no significant effect on other parameters. However, with the application of serotonin+salt, an increase in the relative water content and proline amount, and a significant decrease in the amount of ion leakage and MDA were detected. When the results were examined, it was determined that the application of serotonin had a decreasing effect on the physiological parameters, especially on the negative results of drought and salt stress. When the antioxidative enzyme gene expressions of plants under salt and drought stress were examined, it was found that serotonin hormone application caused an increase in APX1, SOD, CAT2 and GR1 gene expression, while it caused a decrease in ACS2 gene expression. Serotonin administration under saline conditions caused an increase in P5CS gene expression. There was no study in which serotonin hormone was applied during drought and salt stress in tomatoes, and the data obtained in our study was obtained for the first time with this study. When all these parameters were examined, it was concluded that the application of serotonin hormone to plants under drought and salt stress may be effective in reducing drought and salt stress.