Integrative transcriptomic and proteomic analysis reveals the regulatory mechanisms underlying oilseed rape...

Blackleg disease caused by Leptosphaeria species is a major constraint to rapeseed (Brassica napus) production worldwide. Although resistance to L. maculans is well studied, molecular and temporal responses of B. napus to L. biglobosa, particularly at integrated multi-omics levels, remain poorly understood. Here, we integrated physiological, transcriptomic, and proteomic analyses to characterize defense responses at 72, 120, and 168 h post inoculation (hpi). Physiological assays showed elevated peroxidase (POD), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) activities, and malondialdehyde (MDA) content, indicating oxidative stress-associated defense activation. Multi-omics analyses revealed a temporally coordinated immune reprogramming process. At 72 hpi, pathogen perception, reactive oxygen species (ROS) accumulation, and metabolic adjustment dominated early responses. At 120 hpi, MAPK signaling and antioxidant systems, including glutathione S-transferases (GSTs), were strongly activated. At 168 hpi, phenylpropanoid biosynthesis, lignin deposition, and cell wall remodeling were enhanced, indicating structural reinforcement. Integrated transcriptome-proteome analysis identified key candidate regulators, including GSTs, caffeic acid O-methyltransferase (COMT), short-chain dehydrogenase/reductase (SDR) proteins, and MLP-like protein 28, showing coordinated and stage-specific expression patterns. Collectively, these results reveal a temporally ordered, multi-layered defense network in B. napus, characterized by sequential metabolic reprogramming, immune signaling activation, and structural reinforcement, providing mechanistic insights into L. biglobosa resistance.