Heme Oxygenase/Carbon Monoxide Participates in the Regulation of Ganoderma lucidum Heat-Stress Response, Ganoderic Acid Biosynthesis, and Cell-Wall Integrity

Abstract

Carbon monoxide (CO), a product of organic oxidation processes, arises in vivo principally from the enzymatic reaction of heme oxygenase (HO, transcription gene named HMX1). HO/CO has been found to exert many salutary effects in multiple biological processes, including the stress response. However, whether HO/CO is involved in the regulation of the heat-stress (HS) response of Ganoderma lucidum (G. lucidum) is still poorly understood. In this paper, we reported that under heat stress, the HMX1 transcription level, HO enzyme activity, and CO content increased by 5.2-fold, 6.5-fold and 2-fold, respectively. HMX1 silenced strains showed a 12% increase in ganoderic acid (GA) content under HS as analyzed by HPLC. Furthermore, according to Western blot analysis of the protein phosphorylation levels, HMX1 attenuated the increase in phosphorylation levels of slt2, but the phosphorylation levels were prolonged over a 3 h HS time period. The chitin and glucan content in HMX1 silenced strains increased by 108% and 75%, respectively. In summary, these findings showed that the HO/CO system responds to heat stress and then regulates the HS-induced GA biosynthesis and the cell-wall integrity mediated by the Slt-MAPK phosphorylation level in G. lucidum.

Study of the Metabolite Changes in Ganoderma lucidum under Pineapple Leaf Residue Stress via LC-MS/MS Coupled with a Non-Targeted Metabolomics Approach

“…Its growth requires nutritional components such as carbon, nitrogen, inorganic salts, and vitamins [12]. Carbon is a crucial component, providing the energy for mycelial growth but also participating in the formation of vitamins, proteins, and amino acids in the mycelium [13]. Nitrogen is also mandatory for the growth of the mycelium of G. lucidum, which mainly absorbs nitrogenous compounds in the reduced state, such as amino acids, proteins, urea, ammonia, ammonium salts, and nitrates [14].…”