How a Key Enzyme Influences Growth and Sugar Production in Reishi Mushrooms

Greg Howard
22nd July, 2024

How a Key Enzyme Influences Growth and Sugar Production in Reishi Mushrooms

Image Source: Natural Science News, 2024

Key Findings

  • The study from Jiangnan University, China, explored the role of α-1,3-glucosyltransferase (GLAGT) in Ganoderma lucidum
  • Overexpressing the glagt gene reduced fungal growth by up to 79.61% and decreased cell-wall thickness by 32.44%
  • Despite reduced growth, overexpression increased intracellular and extracellular polysaccharides by 27.58% and 66.08%, respectively
Ganoderma lucidum, also known as "Lingzhi," is a medicinal mushroom renowned for its health benefits, particularly due to its polysaccharides, which exhibit various biological activities such as antioxidant, antitumor, and immunomodulatory effects[2]. However, the biosynthesis of these polysaccharides, especially the role of specific enzymes involved, remains an area of active research. A recent study conducted by Jiangnan University, China, sheds light on the role of α-1,3-glucosyltransferase (GLAGT) in the production of these valuable compounds in G. lucidum[1]. The study found that over-expression of the glagt gene in G. lucidum significantly suppressed fungal growth, with the maximum biomass and mycelial growth rate decreasing by 21.78% and 79.61%, respectively. This behavior contrasts with the well-understood role of β-1,3-glucosyltransferase, which is crucial for polysaccharide production but does not similarly inhibit growth[3]. Furthermore, the fungal pellet diameter and cell-wall thickness decreased by 38% and 32.44%, respectively, while the production of intracellular and extracellular polysaccharides increased by 27.58% and 66.08%. On a molecular level, overexpressing the glagt gene had several significant effects. It downregulated the citrate synthase and isocitrate dehydrogenase genes in the TCA cycle, disrupting energy metabolism and fungal growth. Conversely, it upregulated key enzymes involved in UDP-glucose synthesis and glycosyltransferases (gl24465, gl24971, and gl22535), as well as universally increasing the transcriptional level of glucosidases gl21451, gl30087, and gl24581 by 22%-397%. These changes contributed to cell-wall thinning, facilitating polysaccharides export[4]. Conversely, downregulation of the glagt gene promoted G. lucidum growth while decreasing polysaccharides production, highlighting the enzyme's dual role in growth suppression and polysaccharide synthesis. This finding is particularly intriguing given the established importance of polysaccharides in the medicinal properties of Ganoderma species[5]. The study thus provides new insights into the biosynthesis pathways of these bioactive compounds. The findings from this study tie together previous research on the biosynthesis and function of fungal polysaccharides. For instance, the role of glucan synthases in cell wall assembly and glucan synthesis in edible fungi has been well-documented[3][4]. This study expands on that knowledge by elucidating the specific role of α-1,3-glucosyltransferase in G. lucidum, thereby contributing to a more comprehensive understanding of polysaccharide biosynthesis in fungi. In summary, this study from Jiangnan University provides valuable insights into the role of α-1,3-glucosyltransferase in G. lucidum, revealing its dual function in suppressing fungal growth and promoting polysaccharide production. These findings pave the way for further exploration of polysaccharide biosynthesis pathways, potentially leading to enhanced production of these bioactive compounds for therapeutic use.

GeneticsBiochemMycology

References

Main Study

1) Roles of α-1,3-glucosyltransferase in growth and polysaccharides biosynthesis of Ganoderma lucidum.

Published 19th July, 2024

https://doi.org/10.1016/j.ijbiomac.2024.134031

Related Studies

2) Molecular mechanisms of bioactive polysaccharides from Ganoderma lucidum (Lingzhi), a review.

https://doi.org/10.1016/j.ijbiomac.2020.02.035

3) Biochemical and structural characterization of a glucan synthase GFGLS2 from edible fungus Grifola frondosa to synthesize β-1, 3-glucan.

https://doi.org/10.1186/s13068-023-02380-6

4) Recent insights into glucans biosynthesis and engineering strategies in edible fungi.

https://doi.org/10.1080/07388551.2023.2289341

5) Chemical features of Ganoderma polysaccharides with antioxidant, antitumor and antimicrobial activities.

https://doi.org/10.1016/j.phytochem.2014.10.011


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