Deciphering salt stress effects on soil carbon cycling: Microbial gene networks drive alfalfa productivity in saline agroecosystems

The role of microbial carbon cycling genes in the regulation of plant performance under salt stress is still unknown. This study explored how salt stress affects the root microbiota of alfalfa (Medicago sativa L.) and alters the expression of key genes of the carbon cycle (such as GH136, GT84, GT2_trans_2_3). By metagenomic analysis of the effects of different salinity on alfalfa, we found that salt stress of 100 mmol/L promoted the growth of alfalfa. Higher salt concentrations inhibited its productivity and microbial biomass. Changes in microbial gene networks have an important impact on soil carbon dynamics and the interactions between plants and microorganisms. Notably, we found associations between genes and plant traits such as soil C/N and C/H ratios, as well as leaf width and root length. This study for how microbial functional genes regulating saline crop growth in agricultural ecosystem provides a new understanding.At the same time, a new strategy for improving the salt tolerance and productivity of alfalfa in saline soil is proposed.