Transcriptomic Analysis of Salicylic Acid Promoting Seed Germination of Melon under Salt Stress

Abstract

This study investigated how salicylic acid (SA) mediates the response of melon (Cucumis melo) seeds to salt stress using physiological and transcriptomic methods. The effects of SA on the antioxidant enzymes, osmoregulatory substances, and transcriptome of melon seeds under salt stress were investigated using sodium chloride (NaCl, 100 mmol·L−1) as the stress stimulant and SA + NaCl (0.25 mmol·L−1 + 100 mmol·L−1) as the alleviation treatment. The results showed that SA positively influences salt tolerance by increasing the activity of superoxide dismutase activity (SOD) and catalase activity (CAT) while decreasing proline content (Pro). Differentially expressed genes (DEGs) were identified by transcriptome data analysis, of which 2958 were up-regulated, and 2157 were down-regulated. These genes were mainly involved in the mitogen-activated protein kinase (MAPK) signaling pathway and plant hormone signal transduction, lipid metabolism (linoleic and α-linolenic fatty acid metabolism), biosynthesis of secondary metabolites (phenylpropanoid pathway and flavonoid biosynthesis), and related pathways. Further analysis revealed that SA might alleviate salt stress by initiating a series of signaling pathways under salt stress, participating in lignin biosynthesis to improve cell wall stability, and positively regulating lipoxygenase (LOX) genes. These results provide valuable information and new strategies for future salt resistance cultivation and high melon yield.