**E**ff**ects of GGT and C-S Lyase on the Generation of Endogenous Formaldehyde in** *Lentinula edodes* **at Di**ff**erent Growth Stages**

**Xiaoyu Lei 1, Shuangshuang Gao 1, Xi Feng 2, Zhicheng Huang 1, Yinbing Bian 3, Wen Huang 1,\* and Ying Liu 1,\***


Academic Editor: Stefano Serra

Received: 13 October 2019; Accepted: 18 November 2019; Published: 20 November 2019

**Abstract:** Endogenous formaldehyde is generated as a normal metabolite via bio-catalysis of γ-glutamyl transpeptidase (GGT) and L-cysteine sulfoxide lyase (C-S lyase) during the growth and development of *Lentinula edodes*. In this study, we investigated the mRNA and protein expression levels, the activities of GGT and C-S lyase, and the endogenous formaldehyde content in *L. edodes* at different growth stages. With the growth of *L. edodes*, a decrease was found in the mRNA and protein expression levels of GGT, while an increase was observed in the mRNA and protein expression levels of C-S lyase as well as the activities of GGT and C-S lyase. Our results revealed for the first time a positive relationship of formaldehyde content with the expression levels of *Csl* (encoding Lecsl) and Lecsl (C-S lyase protein of *Lentinula edodes*) as well as the enzyme activities of C-S lyase and GGT during the growth of *L. edodes*. This research provided a molecular basis for understanding and controlling the endogenous formaldehyde formation in *Lentinula edodes* in the process of growth.

**Keywords:** *Lentinula edodes*; endogenous formaldehyde; GGT; C-S lyase; expression levels
