Nitric oxide (NO), as a ubiquitous gas signaling molecule, modulates various physiological and biochemical processes and stress responses in plants. In our study, the NO donor nitrosoglutathione (GSNO) significantly promoted tomato seedling growth under NaCl stress, whereas NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide potassium (cPTIO) treatment reversed the positive effect of NO, indicating that NO plays an essential role in enhancing salt stress resistance. To explore the mechanism of NO-alleviated salt stress, the transcriptome of tomato leaves was analyzed. A total of 739 differentially expressed genes (DEGs) were identified and classified into different metabolic pathways, especially photosynthesis, plant hormone signal transduction, and carbon metabolism. Of these, approximately 16 and 9 DEGs involved in plant signal transduction and photosynthesis, respectively, were further studied. We found that GSNO increased the endogenous indoleacetic acid (IAA) and salicylic acid (SA) levels but decreased abscisic acid (ABA) and ethylene (ETH) levels under salt stress conditions. Additionally, GSNO induced increases in photosynthesis pigment content and chlorophyll fluorescence parameters under NaCl stress, thereby enhancing the photosynthetic capacity of tomato seedlings. Moreover, the effects of NO mentioned above were reversed by cPTIO. Together, the results of this study revealed that NO regulates the expression of genes related to phytohormone signal transduction and photosynthesis antenna proteins and, therefore, regulates endogenous hormonal equilibrium and enhances photosynthetic capacity, alleviating salt toxicity in tomato seedlings.

Abiotic stress is one of the major threats affecting plant growth and production. The harm of abiotic stresses includes the disruption of cellular redox homeostasis, reactive oxygen species (ROS) production, and oxidative stress in the plant. Plants have different mechanisms to fight stress, and these mechanisms are responsible for maintaining the required homeostasis in plants. Recently, the study of gasotransmitters in plants has attracted much attention, especially for abiotic stress. In the present review, abiotic stressors were mostly found to induce gasotransmitter production in plants. Meanwhile, these gasotransmitters can enhance the activity of several antioxidant enzymes, alleviate the harmfulness of ROS, and enhance plant tolerance under various stress conditions. In addition, we introduced the interaction of gasotransmitters in plants under abiotic stress. With their promising applications in agriculture, gasotransmitters will be adopted in the near future.