Soil metagenome and metabolome of peanut intercropped with sorghum reveal a prominent role of carbohydrate metabolism in salt-stress response

To understand the underlying mechanisms of the salt-stress response in peanuts intercropped with sorghum, soil metabolomics and metagenome sequencing were used to examine the metabolic profile and microbial composition of solo-cropped peanut (SP) and intercropped peanut (IP) under normal (N) and salt-stressed (S) soil conditions. In this investigation, 124 potential compounds were identified and categorized into 11 classes, with carbohydrates constituting the majority. Pathway enrichment analysis revealed that the most differentially expressed metabolic pathway was "carbohydrate metabolism," and the main metabolites (e.g., D-Allose 2, Sucrose, Sorbitol 1, and Fructose 1) were more abundant in S-IP than in S-SP. Furthermore, the metagenomic analysis revealed that the relative abundances of Actinobacteria, Nitrospira, Massilia, and additional microbial taxa were significantly higher in S-IP than in S-SP. In addition, microbes exhibited a significant positive association with Sucrose and Sorbitol 1, and numerous microbial functions were involved in regulating carbohydrate metabolism in response to salt stress. Therefore, peanuts intercropped with sorghum under salt stress indirectly influenced the recruitment of beneficial microbial communities by altering the composition and content of metabolites, potentially increasing peanut's tolerance. These findings may provide a foundation for elucidating intercropping to improve the salt tolerance of peanuts as well as elucidate important information on the crucial metabolites and microbes that regulate the salt-stress response.