Transcriptomic insights into common defense mechanisms of Pleurotus ostreatus, Agaricus bisporus, and Lentinula edodes against Pseudomonas tolaasii-induced browning

This study investigated gene expression patterns associated with the browning of mushroom fruiting bodies caused by <i>Pseudomonas tolaasii</i> infection. To address this, <i>Pleurotus ostreatus, Agaricus bisporus</i>, and <i>Lentinula edodes</i> were inoculated with <i>P. tolaasii</i>, and morphological changes were examined, followed by transcriptome analysis to identify common and differentially expressed genes across the three species. Hydrophobin and glycoside hydrolase family 13 genes, associated with α-glucan metabolism and cell wall-related processes, were commonly downregulated, whereas laccase- and histidine kinase-related genes involved in melanin biosynthesis were significantly upregulated (log2 fold change ≥ 2, p ≤ 0.05). Notably, laccase induction represented a conserved transcriptional response to <i>P. tolaasii</i> infection, although the magnitude of induction varied among species. These findings provide molecular evidence linking mushroom browning to the transcriptional activation of defense-related genes and highlight laccase as a key, yet species-dependent, component of the response to <i>P. tolaasii</i> infection.