Integrated transcriptome and translatome analyses reveal the early regulatory network of Brassica napus roots in response to the growth-promoting rhizobacterium Pseudomonas simiae WCS417

Interactions between plant roots and complex microbial communities are critical for plant environmental adaptation. Pseudomonas simiae WCS417, a Gram-negative plant growth-promoting rhizobacterium (PGPR), is a model organism in plant-microbe interaction research and featured in over 750 studies since the 1990s. However, the translatome dynamics induced by WCS417 remain poorly understood. This study employed an integrated multi-omics approach, combining transcriptome (RNA-seq) and translatome (RNC-seq) analyses, to systematically investigate the transcriptional and translational regulatory networks in Brassica napus roots during early colonization by WCS417. Our results demonstrate that WCS417 significantly promotes lateral root formation, suppresses primary root elongation, and increases plant biomass. At the molecular level, WCS417 inoculation triggered extensive changes in gene expression and translation at 30 minutes and 6 hours post-inoculation, affecting key processes including phytohormone signaling, cell wall remodeling, immune responses, and abiotic stress adaptation. Notably, although transcript levels of some immune-related genes were downregulated, their translation efficiency was significantly enhanced, suggesting that plants maintain basal immunity while facilitating symbiotic establishment. Furthermore, WCS417 dynamically regulated genes involved in nitrogen/phosphorus uptake and core low-temperature response transcription factors in Brassica napus roots. These findings reveal a multi-layered regulatory mechanism by which WCS417 optimizes root system architecture and balances immunity with growth in Brassica napus , providing new insights into plant-microbe interactions.