Expression of Small Secreted Peptide Genes in Abiotic Stress in Plants Interacting with Plant Growth-Promoting Bacteria.

Small secreted peptides (SSPs) are a promising class of signaling molecules that regulate plant growth, development, and stress responses. Under abiotic stress conditions, SSPs can modulate the physiological and molecular responses, thereby influencing plant adaptation. Based on publicly available transcriptomic data on Arabidopsis thaliana, SSP gene expression was analyzed in plants exposed to dehydration or a higher salinity in combination with inoculation by plant growth-promoting bacteria (PGPBs). Candidate genes involved in plant adaptation to stress conditions upon interaction with PGPBs were thus identified. In salt stress, inoculation with Enterobacter sp. SA187 mitigated stress‑induced suppression of growth‑related genes. In dehydration stress, Aeromonas sp. H1 altered expression of genes regulating stomatal development and the root system, but did not affect SSP expression in mock conditions. A combined effect of stress and PGPBs was found to generate a specific transcriptional response. The response is not a simple overlay of two independent reactions, but depends on both the stress type and the bacterial strain.