Arbuscular mycorrhizal fungi promotes carbon metabolism genetic potential in the rhizosphere microbial community of Iris tectorum

Soil carbon metabolism is an important soil biogeochemical cycling process between plants and rhizosphere microorganisms, and chromium (Cr) can disrupt functional genomic changes in rhizosphere microorganisms and inhibit plant growth. Arbuscular mycorrhizal fungi (AMF) can form reciprocal symbiotic systems with the vast majority of terrestrial plants and play an important role in plant growth and abiotic stress. The metagenomic analysis demonstrated that AMF mitigated the toxic effects of Cr stress on I. tectorum, reduced soil Cr content, and notably increased the diversity index and relative abundance of the rhizosphere microbial community of I. tectorum. The dominant phyla were Proteobacteria, Actinobacteria, Chloroflexi, and Bacteroidetes. The major taxa present in the rhizosphere of I. tectorum were resistant to heavy metals and carbon sequestration, especially Anaeromyxobacter and Microbacterium. Reductive citrate cycle (Arnon-Buchanan cycle) is the main pathway of carbon sequestration by rhizosphere microorganisms of I. tectorum. Meanwhile, a total of 419 genomic genes involved in the regulation of carbon cycling in I. tectorum and AMF mycorrhizal symbiosis system were screened using macrogenomics. The results of this study provide a basis for the potential application of wetland plants in combination with AMF for carbon sequestration and remediation of Cr-contaminated soils, but the molecular mechanisms by which AMF regulates the expression of metabolic genes in plants and rhizosphere microorganisms still need to be explored in depth. However, it is still necessary to explore in depth the molecular mechanisms by which AMF regulates the expression of metabolic genes in plants and rhizosphere microorganisms.