To reveal the mechanism of salinity stress alleviation by arbuscular mycorrhizal fungi (AMF), we investigated the growth parameter, soluble sugar, soluble protein, and protein abundance pattern of E. angustifolia seedlings that were cultured under salinity stress (300 mmol/L NaCl) and inoculated by Rhizophagus irregularis (RI). Furthermore, a label-free quantitative proteomics approach was used to reveal the stress-responsive proteins in the leaves of E. angustifolia. The result indicates that the abundance of 75 proteins in the leaves was significantly influenced when E. angustifolia was inoculated with AMF, which were mainly involved in the metabolism, signal transduction, and reactive oxygen species (ROS) scavenging. Furthermore, we identified chorismate mutase, elongation factor mitochondrial, peptidyl-prolyl cis-trans isomerase, calcium-dependent kinase, glutathione S-transferase, glutathione peroxidase, NADH dehydrogenase, alkaline neutral invertase, peroxidase, and other proteins closely related to the salt tolerance process. The proteomic results indicated that E. angustifolia seedlings inoculated with AMF increased the secondary metabolism level of phenylpropane metabolism, enhanced the signal transduction of Ca²⁺ and ROS scavenging ability, promoted the biosynthesis of protein, accelerated the protein folding, and inhibited the degradation of protein under salt stress. Moreover, AMF enhanced the synthesis of ATP and provided sufficient energy for plant cell activity. This study implied that symbiosis of halophytes and AMF has potential as an application for the improvement of saline-alkali soils.

Owing to complex pore systems and chemical substances, soil aggregates provide a spatially heterogeneous microenvironment for adsorption capacity and microbial survival. As the widely used pesticide in farmlands, atrazine environmental behavior is not well known at the aggregate scale. In this study, Mollisol soil samples were sieved into four aggregate-size classes: large macroaggregates (>2 mm, LMa), small macroaggregates (1-2 mm, SMa), microaggregates (0.25-1 mm, Mia) and primary particles (<0.25 mm, P). The pore characteristics of each aggregate fraction was visualized by non-invasive X-ray three-dimensional microscopic computed tomography (3D-CT) combined with pore network extraction. The adsorption kinetics of atrazine in each aggregate-size fraction can be described well by a pseudo-second-order kinetic model. The adsorption isothermal process of atrazine can be better fitted by the Langmuir isotherm model than Freundlich isotherm model. There was an obvious linear correlation between the maximum atrazine adsorption capacity and aggregate SOC content as well as TN. In addition, the abundance of bacteria, actinomycetes and anaerobic bacteria in P was totally higher than those in SMa and Mia. Although pH is strongly linked to the bacterial community in the aggregate fraction, aggregate particle size explained 18 % for shaping the microbial community. Therefore, chemical properties and pore characteristics of each soil aggregate fraction both contributed to performance of atrazine adsorption behavior and microbial community.