Interactions between the soil bacterial community assembly and gene regulation in salt-sensitive and salt-tolerant sweet sorghum cultivars

Complex bacterial communities in the rhizosphere play a crucial role in plant growth and stress tolerance. These communities vary across cultivars and external environments. However, the influences of salt stress on the structural composition of bacterial microbiome and gene expression of salt-sensitive and salt-tolerant sweet sorghum (Sorghum bicolor L. Moench) cultivars have not been studied sufficiently. Here, we employed a combination of 16S rRNA gene profiling and RNA-seq analysis to characterize changes in root-associated microbiomes and determine differentially expressed genes (DEG) in the roots of salt-tolerant M-81E and salt-sensitive 'Roma' var. sweet sorghum cultivars under soil conditions with/without salinity. Results revealed that the two contrasting sweet sorghum genotypes selectively filtered and recruited distinct root microbiota in response to salt stress. M-81E-enriched bacterial taxa were more diverse and exhibited a higher abundance of metabolic functions than Roma-enriched taxa. M-81E-associated bacterial co-occurrence networks were more complex and harboured more positive links than Roma-associated bacterial networks. Furthermore, nine DEG were identified as core salt-responsive genes and were central to the salt tolerance of sweet sorghum. Correlation analysis revealed that the expression of HSP70, a molecular chaperone, is linked to the recruitment of numerous M-81E-enriched bacteria; their relationship needs further exploration. The study supplements the comprehension of the potential role of host-microbe interactions in the response of sweet sorghum to salt stress.