Chalcone Synthase: From Discovery to Biotechnological Applications.

The Biosynthesis of a Fungal Flavonoid, Chlorflavonin, Precisely Controlled by Two Types of Equilibrium States.

Flavonoids are polyphenolic natural products predominantly isolated from plants and exhibit a diverse array of biological activities. Because they serve as important pharmaceuticals and nutraceuticals, there is a strong demand for their sustainable supply. Chlorflavonin is a rare fungal flavonoid with potent antitubercular activity. While its biosynthetic enzymes are expected to be valuable tools for application in fungal production of flavonoids, the biosynthetic pathway remains unknown. Here, we elucidate the complete biosynthetic pathway for chlorflavonin through detailed functional analysis of each biosynthetic enzyme. Previously, stepwise and straightforward introduction of 3-, 7-, and 8-methoxy; 2'-hydroxy; and 3'-chloro functionalities have been proposed. In contrast to this proposal, we uncovered an intricate biosynthetic route involving a dynamic interconversion between the 6- and 8-methoxy forms of flavonoid skeletons mediated by the chalcone isomerase CfvF and the flavin-dependent oxygenase CfvI. CfvF interconverted the 6- and 8-methoxyflavanones, likely via a chalcone intermediate. CfvI oxidized the chemically inert 2,3-double bond of flavanone, giving the hemiacetal product. Although these enzymes generate products existing in equilibrium states, respective downstream enzymes catalyze selective conversion of one specific species, facilitating smooth progression to the final product. We also solved the crystal structure of CfvK, the dehydratase that selectively converts the 8-methoxy form of the CfvI product. Through analyzing the structure complexed with its substrate and product and site-directed mutagenesis, key residues determining the substrate selectivity were identified. Our comprehensive analysis established a rational framework for preparing 46 flavonoids, including unnatural ones, setting the stage for fungal production of structurally diverse flavonoids.

Research progress on biosynthesis and regulation of monoterpenoid compounds

Monoterpenoids are an important class of plant volatile natural products with broad applications in the food, fragrance, pharmaceutical, and agricultural industries. However, their conventional production largely relies on plant extraction, which is often constrained by low efficiency, high cost, and limited sustainability. Structurally, monoterpenoids can be classified into acyclic, monocyclic, and bicyclic types, and their structural diversity is closely associated with differences in biosynthetic routes and regulatory mechanisms. Their biosynthesis depends on precursor supply from the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways, followed by terpene synthase (TPS)-mediated scaffold formation and subsequent modification reactions. In addition, monoterpenoid accumulation is regulated by multiple factors, including environmental cues, phytohormone signaling, transcriptional regulation, and epigenetic or post-transcriptional control. Meanwhile, substantial progress has been made in the heterologous production of monoterpenoids in microbial platforms such as Escherichia coli and Saccharomyces cerevisiae through metabolic engineering and synthetic biology. This review summarizes recent advances in monoterpenoid biosynthesis, multilevel regulation, and heterologous production, with particular emphasis on major bottlenecks and optimization strategies for sustainable and efficient biomanufacturing.

Unraveling the Chemical and Enzymatic Logic of Cytokinin Biosynthesis and Inactivation in Fusarium.

As a core family of hormone regulating plant growth and development, the biosynthesis and inactivation mechanisms of cytokinins (CKs) have been well studied in plants. However, these processes remain largely uncharacterized in other organisms, particularly fungal phytopathogens. Here, we identify a distinct pathway of CKs from Fusarium and unravel the chemical and enzymatic logic of biosynthesis and inactivation, which mainly includes: (1) the IPT-LOG fusion enzyme FexA catalyzes N6-dimethylallylation of AMP and cleavage of the C1″-N9 bond to form iP (1); (2) the CYP450 FexB not only hydroxylates 1 to generate the canonical plant-type CKs trans-zeatin (tZ, 2) and cis-zeatin (cZ, 3), but also sequentially catalyzes C4'-N6 cyclization to produce a pyrrole derivative (6); (3) the BBE-like oxidase FexC independently mediates oxidative cleavage of compounds 1-3 and unexpectedly converts 1 to C1'-keto-iP (16); (4) FexC and the NmrA-like SDR FexD cooperate to catalyze double bond isomerization, yielding two novel CKs (17 and 19), where FexD functions as a rare NADPH-dependent 1,4-reductase. Biological activity assays demonstrate that the noncanonical fungus-specific compounds 6, 17, and 19 represent new inactive CK forms for plants, whereas 16 exhibits unexpectedly high activity. Importantly, unlike plants, Fusarium employ double bond isomerization and pyrrole formation as novel strategies for CK inactivation. Our findings uncover unusual functions of fungal CK enzymes and reveal the molecular basis underlying CK biosynthesis and inactivation in plant pathogenic fungi, which provide new insights into the discovery and application of CK derivatives.

[Pharmacological effects, biosynthesis, and production of coumarin compounds: a review].

Phytohormone profiles in macroalgae: A comprehensive review of biochemical diversity and plant growth-promoting effects

This review provides a comprehensive analysis of the phytohormonal landscape across Phaeophyceae, Rhodophyta, and Chlorophyta, and offers a comprehensive framework for utilizing macroalgal biochemistry in sustainable agricultural intensification.

Amaryllidaceae Alkaloids and Isoquinoline Alkaloids: A Perspective on Historical Approaches to Pathway Elucidation

This review compares the historical and methodological trajectories that have shaped IA and AA pathway elucidation, from compound isolation, radiotracer experiments, and biochemical inference to transcriptomics, metabolomics, functional enzymology, isotope-guided active-tissue identification, regulatory studies, and heterologous pathway reconstruction.