Abstract
Soil salinization poses a serious threat to the environment and agricultural productivity worldwide. Studies on the physiological and molecular mechanisms of salinity tolerance in halophytic plants provide valuable information to enhance their salt tolerance. Tangut Nitraria is a widely distributed halophyte in saline–alkali soil in the northern areas of China. In this study, we used a proteomic approach to investigate the molecular pathways of the high salt tolerance of T. Nitraria. We analyzed the changes in biomass, photosynthesis, and redox-related enzyme activities in T. Nitraria leaves from plant seedlings treated with high salt concentration. Comparative proteomic analysis of the leaves revealed that the expression of 71 proteins was significantly altered after salinity treatments of T. Nitraria. These salinity-responsive proteins were mainly involved in photosynthesis, redox homeostasis, stress/defense, carbohydrate and energy metabolism, protein metabolism, signal transduction, and membrane transport. Results showed that the reduction of photosynthesis under salt stress was attributed to the down-regulation of the enzymes and proteins involved in the light reaction and Calvin cycle. Protein–protein interaction analysis revealed that the proteins involved in redox homeostasis, photosynthesis, and energy metabolism constructed two types of response networks to high salt stress. T. Nitraria plants developed diverse mechanisms for scavenging reactive oxygen species (ROS) in their leaves to cope with stress induced by high salinity. This study provides important information regarding the salt tolerance of the halophyte T. Nitraria.
Highlights
Salinization is one of the world’s most serious environmental factors that affect the growing area and productivity of many plants (Stepien and Johnson, 2009)
The proteins in the first group involved in stress resistance, antioxidant and redox homeostasis, amino acid metabolism, carbohydrate metabolism, protein metabolism, and kinase activity (Figure 6, Table S3). These results showed that the proteins in this network played important functions in redox homeostasis, response to stress, signal transduction, and carbohydrate and protein metabolism
Nitraria plants treated with 500 mM NaCl, the majority of proteins were involved in redox homeostasis, photosynthesis, signal transduction, energy, and carbohydrate and protein metabolism
Summary
Salinization is one of the world’s most serious environmental factors that affect the growing area and productivity of many plants (Stepien and Johnson, 2009). More than 6% of the world’s land is affected by high salinity (Munns and Tester, 2008), and increased salinization may lead to a 30% loss of arable land in the 25 years and up to 50% by 2050 (Wang et al, 2008). The increasing damage caused by high salinity has prompted extensive research on plant responses and adaptation mechanisms (Zhu, 2001; Munns and Tester, 2008). Plants are categorized based on their responses to salinity into halophytes and glycophytes. Halophytes have developed unique structures, including salt glands, bladder hairs, succulent tissues, and thick layers of suberin, to tolerate salt stress (Flowers and Colmer, 2008)
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