Lenthionine, a Key Flavor Substance in Lentinula edodes, Is Regulated by Cysteine under Drought Stress

Due to its unique flavor profile, Lentinula edodes has become one of the most popular edible mushrooms in the world, but the regulatory mechanism of its flavor substances has not been revealed. To study the mechanism that regulates the anabolic metabolism of the important flavor substance lenthionine (LT), the effect of cysteine (Cys) synthesized by the cystathionine-γ-lyase (CSE-1) gene participating in the regulation of LT metabolism under drought stress was analyzed. Our results showed that drought stress promoted the accumulation of LT, and the key genes GTT and LECSL were activated. Furthermore, drought stress promoted the accumulation of intracellular Cys and activated the key gene for Cys synthesis, CSE-1. Both inhibition of the CSE enzyme activity by inhibitors and silencing of the CSE-1 gene under drought stress significantly reduced the intracellular contents of Cys and LT, but the inhibition of LT synthesis disappeared after the exogenous addition of Cys. These results indicate that LT synthesis in L. edodes under drought stress is dependent on Cys. In summary, the mechanism of the regulation of flavor substances in edible mushrooms by the environment was revealed for the first time.