Transcriptomic analysis reveals the mechanism of bacterial disease resistance of postharvest button mushroom (Agaricus bisporus)

Brown blotch disease caused by Pseudomonas tolaasii infection is one of the major problems affecting the storage quality of postharvest button mushrooms (Agaricus bisporus). In this study, P. tolaasii treatment accelerated the accumulation of pathogen resistance-related substances/proteins, induced disease resistance-related enzyme activities, and promoted the increase of jasmonic acid (JA) during the whole storage. To gain full insight into the defense mechanisms of button mushrooms against P. tolaasii, a transcriptomics analysis of mushroom samples at 12 h was conducted. A total of 2861 differentially expressed genes (DEGs) were identified, among which there were 1557 up-regulated and 1304 down-regulated genes. Further bioinformatic analysis showed that P. tolaasii inoculation mainly activated shikimate pathway, phenylpropanoid metabolism, sulfur metabolism, methane metabolism, arginine and proline metabolism, cysteine and methionine metabolism, JA biosynthesis and signaling pathways, as well as oxidative phosphorylation pathways. Transcriptomics data combined with qPCR verification indicated that 10 DEGs including PIP1, MET3, AGX, PAL1, GCL, LOX 1/3, PR-like, MYB3R, UCR, and SDHB are the most potential genes involved in the early defense of A. bisporus against P. tolaasii. Additionally, taking the physiological and transcriptomics results together, the existence and important participation of JA biosynthesis and signaling pathways were demonstrated in the disease resistance of A. bisporus, although this organism probably possesses different catalyzing enzymes and transduction pathways with plants. In a word, our findings revealed the mechanism of the button mushroom's early defense response against pathogens, providing a reference for the development of rational approaches to control of mushroom diseases.