Abstract
To clarify the physiological mechanism of the Lentinula edodes (L. edodes) response to high-temperature stress, two strains of L. edodes with different tolerances were tested at different durations of high temperature, and the results showed that there were significant changes in their phenotypes and physiology. To further explore the response mechanism, we established a targeted GC–MS-based metabolomics workflow comprising a standardized experimental setup for growth, treatment and sampling of L. edodes mycelia, and subsequent GC–MS analysis followed by data processing and evaluation of quality control (QC) measures using tailored statistical and bioinformatic tools. This study identified changes in the L. edodes mycelial metabolome following different time treatments at high temperature based on nontargeted metabolites with GC-MS and further adopted targeted metabolomics to verify the results of the analysis. After multiple statistical analyses were carried out using SIMCA software, 74 and 108 differential metabolites were obtained, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the metabolic pathways with significant changes included those related to the following: amino acid metabolism, the glycolysis pathway, the tricarboxylic acid (TCA) cycle, and sugar metabolism. Most amino acids and carbohydrates enriched in these metabolic pathways were upregulated in strain 18, downregulated in strain 18N44, or the synthesis in strain 18 was higher than that in strain 18N44. This result was consistent with the physiological phenotypic characteristics of the two strains under high-temperature stress and revealed the reason why strain 18N44 was more heat-sensitive. At the same time, under high temperature, the decrease of intermediate products in glycolysis and the TCA cycle resulted in carbon starvation and insufficient energy metabolism, thus inhibiting the growth of L. edodes. In addition, the results also showed that the metabolites produced by different L. edodes strains under high-temperature stress were basically the same. However, different strains had species specificity, so the changes in the content of metabolites involved in the response to high-temperature stress were different. This provides a theoretical basis for further understanding the mechanism of the L. edodes response to high temperature and can be used to establish an evaluation system of high-temperature-resistant strains and lay the foundation for molecular breeding of new L. edodes strains resistant to high temperature.
Highlights
Lentinula edodes (L. edodes), called dried mushrooms, are rich in nutrition, have a delicious taste and a variety of health functions, and are known as the Queen of Mushrooms [1,2]
As heat shock duration increased to 12–24 h, mycelial germination lasted for a longer time, while the effects on the recovered growth rate were not significant
This paper focuses on different physiological characteristics of mutant strains and starting strains of L. edodes in response to high-temperature stress, explores the response mechanism to phenotypic changes by nontargeted metabonomics, and provides further validation by targeted metabonomics
Summary
Lentinula edodes (L. edodes), called dried mushrooms, are rich in nutrition, have a delicious taste and a variety of health functions, and are known as the Queen of Mushrooms [1,2]. This species is the second largest edible fungus in the world and one of the major edible fungi produced on a large scale in China [3]. In actual production, the summer temperature in the main production area of L. edodes is much higher than 25 ◦C. This high temperature seriously damages L. edodes. It is of great significance to study the physiological mechanism of resistance to high-temperature stress in L. edodes
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