Exogenous Serotonin Improves Salt Tolerance in Rapeseed (<i>Brassica napus</i> L.) Seedlings

• Main Authors: Yue Liu, Xiaoyu Ding, Yan Lv, Yong Cheng, Chunsheng Li, Lei Yan, Shanshan Tian, Xiling Zou
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Agronomy
• Subjects: serotonin; <i>Brassica napus </i>L. (rapeseed); salinity; seedling
• Online Access: https://www.mdpi.com/2073-4395/11/2/400

Serotonin is a well-known agent that plays various roles in animals, and is little known in plants. In this study, the effect of exogenous serotonin was tested on <i>Brassica napus L</i>. (rapeseed) under salt stress. The results revealed that exogenous application of 200 µmol/L serotonin had the best protection under salinity. Exogenous serotonin effectively alleviated the growth inhibition of seedlings caused by salinity, and significantly promoted the accumulation of the fresh and dry weights of roots and shoots. Besides, although the H₂O₂ and malondialdehyde (MDA) contents were raised under salinity, they were reduced by exogenous serotonin. The chlorophyll content was decreased under salinity, and was increased by exogenous serotonin. Under salinity, serotonin effectively activated antioxidant enzyme system through improving the catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities, and the expression of <i>POD7</i>, <i>CAT3 </i>and <i>Cu-SOD </i>genes was also up-regulated. The results also revealed exogenous serotonin increased the solute content by promoting the accumulation of soluble sugar and protein. In conclusion, salinity caused a toxicity to seedlings through oxidative damage to chlorophyll and cell membrane integrity, and serotonin possessed the ability of scavenging reactive oxygen species, osmotic pressure regulation and promoting growth, thus alleviating salinity of rape seedlings.