Sanghuangporus baumii is a traditional medicinal fungus that contains triterpenoids with important pharmacological effects. However, the level of triterpenoids produced by S. baumii is far below the level demanded for application, and the pathway of triterpenoids biosynthesis is poorly understood. In this study, we established an Agrobacterium tumefaciens-mediated transformation system for the first time and transferred the key gene isopentenyl diphosphate isomerase ( IDI) involved in triterpenoids biosynthesis into S. baumii. The transcript level of IDI and the total triterpenoids content of the IDI transformant (IT) strain were significantly increased with respect to the wild-type (WT) strain. Then, we investigated the individual triterpenoids contained in S. baumii using metabolome and found 10 individual triterpenoids. All individual triterpenoids produced by IT strain showed the upward trend, were 1.76-10.03 times higher than those produced by the WT strain. Meanwhile, those individual triterpenoids showed significant positive correlation with the IDI gene. The findings provide valuable information about the biosynthetic pathway of triterpenoids and provide a strategy to cultivate S. baumii strains with high triterpenoids content.

Sanghuangporus baumii is a traditional medicinal fungus that produces pharmacological terpenoids, but natural resources are insufficient for applications, and growth and development mechanisms are poorly understood. Combining metabolomic and transcriptomic analyses, we identified four terpenoid hormones and a central gene isopentenyl diphosphate isomerase (IDI) involved in growth and development. The importance of the four terpenoid hormones was further confirmed by exogenous hormones addition, we found that Cis-Zeatin (CZ) plays a major role in the mycelia stage, Trans-Zeatin (TZ) and Gibberellin A4 (GA4) are important in the primordia stage, GA4 is crucial for the fruiting bodies stage, and Abscisic Acid (ABA) may be a marker of maturity. Later, hormone content determination and qRT-PCR were used to verify the growth and development mechanism, and finally it was confirmed that IDI gene affects the content of terpenoid hormones content by regulating the transcript level of terpenoid biosynthesis genes, thus affecting the morphological changes of S. baumii. Our results illuminate the growth and development mechanisms of S. baumii, and may promote the breeding and utilisation of high-quality varieties.