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 Brassica napus L. (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 POD7, CAT3 and Cu-SOD 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.

Peanut (also called groundnut, Arachis hypogaea L.) seeds are used for producing edible oils and functional foods, and offer a rich source of lipids, proteins and carbohydrates. However, the location of these metabolites has not yet been firmly established. In the present study, the matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) technique was applied to investigate spatial distribution of lipids and other key components in seeds of three peanut cultivars (ZH9, KQBH, HP). A total of 103 metabolites, including 34 lipid compounds, were putatively identified by MALDI-MSI. The abundance and spatial distribution of glycerolipids (GLs) and glycerophospholipids (GPs) were compared among the three peanut cultivars. All the identified lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE) and phosphatidylcholines (PCs) were distributed mainly in the inner part of seeds. The visualization of phosphatidic acids (PAs) and triacylglycerols (TGs) revealed a dramatic metabolic heterogeneity between the different tissues making up the seed. The non-homogeneous spatial distribution of metabolites appeared to be related to the different functions of particular tissue regions. These results indicated that MALDI-MSI could be useful for investigating the lipids of foodstuffs from a spatial perspective. The present study may contribute to the development of oil crops with higher oil yields, and to improvement of food processing.

Trehalose-6-phosphate phosphatase (TPP) is a pivotal enzyme in trehalose biosynthesis which plays an essential role in plant development and in the abiotic stress response. However, little is currently known about TPPs in groundnut. In the present study, a total of 16 AhTPP genes were identified, and can be divided into three phylogenetic subgroups. AhTPP members within the same subgroups generally displayed similar exon–intron structures and conserved motifs. Gene collinearity analysis revealed that segmental duplication was the primary factor driving the expansion of the AhTPP family. An analysis of the upstream promoter region of AhTPPs revealed eight hormone- and four stress-related responsive cis-elements. Transcriptomic analysis indicated high expression levels of AhTPP genes in roots or flowers, while RT-qPCR analysis showed upregulation of the six tested genes under different abiotic stresses, suggesting that AhTPPs play roles in growth, development, and response to various abiotic stresses. Subcellular localization analysis showed that AhTPP1A and AhTPP5A were likely located in both the cytoplasm and the nucleus. To further confirm their functions, the genes AhTPP1A and AhTPP5A were individually integrated into yeast expression vectors. Subsequent experiments demonstrated that yeast cells overexpressing these genes displayed increased tolerance to osmotic and salt stress compared to the control group. This study will not only lay the foundation for further study of AhTPP gene functions, but will also provide valuable gene resources for improving abiotic stress tolerance in groundnut and other crops.