Nitric Oxide Enhanced Salt Stress Tolerance in Tomato Seedlings, Involving Phytohormone Equilibrium and Photosynthesis

Abstract

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.

Protective Effects of Sodium Nitroprusside on Photosynthetic Performance of Sorghum bicolor L. under Salt Stress

“…Second, NO may act as a signaling molecule in a chain of events that leads to changes in gene expression [ 30 ]. Exogenous NO application has been shown to influence plant responses to salt stress [ 5 , 28 , 32 , 38 , 39 ], drought stress [ 38 , 40 ], excess light [ 41 ], low and high temperatures [ 42 ], ozone, UV-B [ 42 ], and heavy-metal stress [ 37 , 38 , 43 ]. The information on the impact of NO on plants can sometimes be contradictory, because the effects depend on the plant species and seedling age, as well as the duration, and severity of the abiotic stress [ 31 , 33 , 44 ].…”

Sodium Nitroprusside Improves Bamboo Resistance under Mn and Cr Toxicity with Stimulation of Antioxidants Activity, Relative Water Content, and Metal Translocation and Accumulation

“…Nitric oxide is a small signaling molecule and a crucial regulator of the plant life cycle [11], which acts positively during various stages of the plant life cycle, such as germination, flowering, development, and senescence, as well as in the amelioration of abiotic stress [2,18]. Thus, this neutral and tiny redox molecule has a great capacity to spread through the cell membrane and is frequently referred to as a dynamic molecule [11].…”

Mitogen-Activated Protein Kinase Is Involved in Salt Stress Response in Tomato (Solanum lycopersicum) Seedlings

“…In our study, DEGs related plant hormone ETH, ABA and JA were identified in the MAPK signal pathway during salt stress ( Figure 4 ). ETH is a gaseous hormone involved in various aspects of plant biology, including germination, plant growth, organ senescence and fruit ripening [ 23 , 24 ]. In our study, 11 DEGs related to ETH signaling in the MAPK pathway, including ETH receptor , ETR , EIN/ EIL , ethylene response factor ERF and CHI were regulated under salt stress.…”