De novo transcriptome analysis of high-salinity stress-induced antioxidant activity and plant phytohormone alterations in Sesuvium portulacastrum

Abstract

<i>Sesuvium portulacastrum</i> has a strong salt tolerance and can grow in saline and alkaline coastal and inland habitats. This study investigated the physiological and molecular responses of <i>S. portulacastrum</i> to high salinity by analyzing the changes in plant phytohormones and antioxidant activity, including their differentially expressed genes (DEGs) under similar high-salinity conditions. High salinity significantly affected proline (Pro) and hydrogen peroxide (H₂O₂) in <i>S. portulacastrum</i> seedlings, increasing Pro and H₂O₂ contents by 290.56 and 83.36%, respectively, compared to the control. Antioxidant activities, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), significantly increased by 83.05, 205.14, and 751.87%, respectively, under high salinity. Meanwhile, abscisic acid (ABA) and gibberellic acid (GA₃) contents showed the reverse trend of high salt treatment. <i>De novo</i> transcriptome analysis showed that 36,676 unigenes were matched, and 3,622 salt stress-induced DEGs were identified as being associated with the metabolic and biological regulation processes of antioxidant activity and plant phytohormones. POD and SOD were upregulated under high-salinity conditions. In addition, the transcription levels of genes involved in auxin (<i>SAURs</i> and <i>GH3</i>), ethylene (<i>ERF1</i>, <i>ERF3</i>, <i>ERF114</i>, and <i>ABR1</i>), ABA (<i>PP2C</i>), and GA₃ (<i>PIF3</i>) transport or signaling were altered. This study identified key metabolic and biological processes and putative genes involved in the high salt tolerance of <i>S. portulacastrum</i> and it is of great significance for identifying new salt-tolerant genes to promote ecological restoration of the coastal strand.