Strigolactones: From Fundamental Biology to Applications in Tree Breeding.

Recent progress in strigolactone biosynthesis and transport in Arabidopsis and rice.

Strigolactones (SLs) are a class of plant hormones that regulate diverse developmental processes and environmental responses. SLs also play important roles as allelochemicals in interactions with arbuscular mycorrhizal fungi (AMF) and root parasitic plants in the rhizosphere. Since their discovery as plant hormones nearly 20 years ago, SL biosynthesis, transport, and signaling have been extensively studied, primarily by characterizing mutants with increased shoot branching and by utilizing reverse genetic approaches in various plant species. Emerging evidence has revealed a series of new components of SL biology, expanding our knowledge of how a single plant species produces various types of SLs with diverse chemical structures and how SLs are released from roots into the soil. However, the bioactive forms of SLs that function as plant hormones and the mechanisms underlying their root-to-shoot transport have not yet been clearly elucidated. In this review, we summarize the current understanding of SL biosynthesis and transport in Arabidopsis thaliana and Oryza sativa. In addition, we discuss the physiological functions of different SL species as plant hormones and rhizosphere signaling molecules, which largely remain unresolved.

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

Characterization of terpene synthase from Piper nigrum during biotic stress

Terpene synthases (TPS) play a vital role in the biosynthesis of secondary metabolites involved in plant defense, development and stress response. Piper nigrum (black pepper), a commercially important spice crop, produces diverse terpenoids, yet the genetic basis of these biosynthetic pathways remains underexplored. In this study, we identified and characterized a terpene synthase gene (PnTPS) from P. nigrum using a biocomputational and molecular approach. Specific primers were designed from the PnTPS gene sequence retrieved from the NCBI database and used for PCR amplification in leaf and stem tissues. The amplified product was sequenced and the resulting gene was identified as PCARF which is likely involved in the biosynthesis of caryophyllene, a key sesquiterpene compound associated with stress tolerance and antimicrobial activity. Functional domain analysis via ScanProsite revealed the presence of a ferredoxin type iron sulphur binding domain, characteristic of certain terpene synthases. This study provides the molecular evidence linking a PnTPS-derived gene to caryophyllene biosynthesis in P. nigrum, highlighting its potential role in plant defense. The findings pave the way for functional validation and genetic improvement strategies aimed at enhancing biotic stress resistance in black pepper.

Mechanism of Terpene Formation in Pogostemon cablin cv. Jing Huoxiang Revealed by Metabolome and Transcriptome Analysis

Pogostemon cablin (Blanco) Benth. cv. ‘Jing Huoxiang’, is a valuable medicinal plant widely studied for its aboveground tissues, which are rich in bioactive compounds such as patchouli alcohol. However, systematic investigations into the biosynthesis of sesquiterpenes in its underground parts (roots) remain limited, with several critical knowledge gaps: (1) the metabolic basis of root-specific accumulation of polycyclic sesquiterpenes is unclear; (2) key terpene synthase (TPS) gene resources remain underexplored; and (3) the regulatory network of terpenoid biosynthesis is poorly understood. Addressing these questions is essential for the rational design and efficient production of terpene synthases. In this study, we integrated metabolomic and transcriptomic approaches to systematically characterize terpenoid profiles across different tissues of P. cablin and elucidate their biosynthetic regulation. Using GC-MS analysis, we identified distinct terpenoid compositions in roots, stems, leaves, flowers, and glandular trichomes. Notably, patchouli alcohol and pogostone accounted for over 60% of the total volatile oil content, while roots specifically accumulated polycyclic sesquiterpenes such as β-caryophyllene and α-humulene. Through transcriptome sequencing and bioinformatic analysis, we comprehensively annotated the TPS gene family, revealing that the TPS-a subfamily (34 genes) was the most abundant in P. cablin, with several members exhibiting root-predominant expression. Co-expression network analysis further identified candidate genes encoding potential high-efficiency polycyclic sesquiterpene synthases and uncovered a β-caryophyllene/α-humulene-regulated tertiary metabolic pathway. Our findings not only fill a critical gap in understanding sesquiterpene biosynthesis in the underground tissues of P. cablin but also provide a foundation for synthetic biology-based optimization of terpenoid production. This research paves the way for the efficient biosynthesis of sesquiterpenes to meet industrial demands in pharmaceuticals, fragrances, and biofuels.

Chalcone Synthase: From Discovery to Biotechnological Applications.

Flavonoids, a class of phenolic compounds widely distributed throughout the plant kingdom, exhibit extensive physiological and pharmacological properties. Chalcone synthase (CHS), the key and rate-limiting gateway enzyme in flavonoid biosynthesis, catalyzes the condensation reaction between malonyl-CoA and p-coumaroyl-CoA to produce chalcone, the core C6-C3-C6 skeleton of flavonoids and related secondary metabolites. This review systematically summarizes the current knowledge of CHS, focusing on its protein structure, catalytic mechanism, evolutionary origin, and divergence patterns. It further elaborates on the precisely orchestrated multilayered regulation of CHS, including tissue-specific and developmental transcription mediated by MYB, bHLH, and WD40 transcription factors, responses to key environmental cues (light and biotic/abiotic stress stimuli), and post-translational modifications (ubiquitination and phosphorylation) that modulate its stability and catalytic activity. Additionally, targeted rational design and metabolic engineering strategies (gene-directed evolution, heterologous expression, pathway optimization) to efficiently enhance CHS performance in microbial and plant cell factories for boosted flavonoid production are summarized. This comprehensive analysis provides a solid theoretical and practical basis for optimizing CHS function and flavonoid biosynthesis, facilitating the sustainable development and practical implementation of industrial and agricultural applications of these bioactive compounds.

Brassinosteroids as phytohormonal shields against micro- and nanoplastic stress in plants

Microplastics (MPs) and nanoplastics (NPs) are biologically active stressors in agricultural soils, where they alter soil physical structure, disrupt rhizosphere processes, impair water and nutrient acquisition, and provoke oxidative and hormonal disequilibrium in plants. Brassinosteroids (BRs), particularly brassinolide and 24-epibrassinolide, have recently emerged as modulators of plant responses to plastic-particle stress. Current evidence indicates that BRs do not detoxify plastics directly. Instead, they reorganize plant performance across interconnected layers: aquaporin-linked NP transport, antioxidant and ascorbate-glutathione metabolism, photosystem II function, hormone crosstalk, secondary metabolism, and rhizosphere feedbacks. In tomato, BRs reduced polystyrene-NP accumulation in edible tissues by suppressing aquaporin genes. In Pinellia ternata and rice, BRs attenuated MP/NP-induced growth inhibition by restoring photosynthetic efficiency and redox control. This mini review synthesizes these findings and frames BRs as eco-hormonal regulators of the plant-plastic-soil interface, while highlighting priorities for field-realistic validation.