# The Metabolic Regulatory Mechanisms of Umami Amino Acids in Stropharia rugosoannulata

## TL;DR

This study explores how metabolic processes in Stropharia rugosoannulata mushrooms influence their umami flavor, focusing on amino acids and enzyme regulation.

## Contribution

The study identifies SrELT1 as a transcriptional regulator of SrCS, linking it to the regulation of umami amino acids through metabolic shifts.

## Key findings

- Overexpression of SrCS in the TCA cycle reduces glutamic acid and aspartic acid levels.
- SrELT1 regulates SrCS and influences the synthesis of umami amino acids.
- Environmental and genetic factors affect SrELT1 and SrCS expression, impacting flavor.

## Abstract

Stropharia rugosoannulata is a widely cultivated edible mushroom known for its nutritional value and umami flavour. Electronic tongue technology and metabolomics revealed that glutamic acid (Glu) and aspartic acid (Asp) levels were positively correlated with umami in the fruiting body developmental stages. Subsequent investigations found that overexpression of SrCS within the TCA cycle resulted in decreased levels of Glu and Asp. Integrating TF-gene-metabolite network modelling with experiments identified SrELT1 as a transcriptional regulator of SrCS. Different temperatures, cultivation substrates and genetics significantly impacted SrELT1 and SrCS expression, thereby affecting Glu and Asp synthesis. The findings suggest that increased Citrate synthase (CS) activity channelled citrate into glycolysis and oxidative phosphorylation without excessive accumulation; in contrast, decreased CS activity shifted metabolism toward the production of metabolites like Glu and Asp. This study provides insights for enhancing the umami of S. rugosoannulata, thereby substantially increasing its market competitiveness in the premium food segment.