Molecular Cloning and Functional Analysis of DXS and FPS Genes from Zanthoxylum bungeanum Maxim

LcMYB43 enhances monoterpene biosynthesis by activating 1-deoxy-D-xylulose-5-phosphate synthase gene expression in Litsea cubeba

MYB transcription factors are crucial regulators involved in various metabolic processes in plants, including terpene biosynthesis. Litsea cubeba, a member of the Lauraceae family, is rich in monoterpenes and regulates their biosynthesis via the key enzyme DXS in the MEP pathway. Seven DXS genes have been identified in this species, but the role of the MYB family in terpene biosynthesis remains unclear. This study conducted a genome-wide characterization of the R2R3-MYB gene family in L. cubeba, analyzing its phylogenetics, expression, and regulatory functions. A total of 129 R2R3-MYB members were identified, with expansion mechanisms involving tandem and segmental duplications. Expression analysis revealed that LcMYB43 activates LcDXS5, a key enzyme in monoterpene biosynthesis. Overexpression of LcMYB43 significantly increased monoterpene accumulation. Y1H, EMSA, and dual-luciferase assays showed that LcMYB43 directly binds to the CAACAG motif in the LcDXS5 promoter, activating its expression. These findings suggest that LcMYB43 enhances monoterpene biosynthesis by promoting LcDXS5 expression, providing new insights into the regulatory mechanisms of monoterpene biosynthesis.

Transcriptome and Metabolome Profiling Provide Insights into Flavonoid Biosynthesis and the Mechanism of Color Formation in Zanthoxylum bungeanum Maxim

The color of Zanthoxylum bungeanum Maxim. (Z. bungeanum) is a key quality indicator and a factor limiting the development of its industry. However, the underlying mechanisms governing color formation remain largely unexplored. In this study, an integrative analysis of transcriptome and metabolome profiles was conducted across four developmental stages to elucidate the color formation mechanism in Z. bungeanum. A total of 137 flavonoids were identified as the fruits ripened, with high levels of differentially accumulated metabolites (DAMs), including tricetin and (-)-epigallocatechin, which were strongly associated with color formation. This suggests their significant contribution to the pigmentation process. Nine differentially expressed genes (DEGs) were identified as candidate genes involved in color development. Additionally, 15 transcription factors (TFs) (12 MYB and 3 bHLH) exhibited expression patterns similar to those of structural genes in the flavonoid biosynthetic pathway, indicating their role in regulating flavonoid synthesis. The bioinformatics analysis of three key flavonoid synthesis genes-ZbCHI, ZbFLS, and ZbANR-revealed that all three proteins exhibit hydrophobic structures without transmembrane domains. Among them, ZbANR possesses signal peptide regions, whereas ZbCHI and ZbFLS do not. Subcellular localization predictions suggest that ZbCHI is most likely localized in the chloroplast, ZbFLS in the cytoplasm, and ZbANR in the membrane. Functional analyses revealed that their transient expression in Nicotiana benthamiana (N. benthamiana) increased the flavonoid content, with ZbANR overexpression producing a distinct white phenotype in the plants. This study enriches transcriptomic data and provides a comprehensive understanding of flavonoid metabolism and the molecular basis of color formation in Z. bungeanum, offering a valuable theoretical foundation for future breeding programs.

Unveiling Anthraquinones: Diverse Health Benefits of an Essential Secondary Metabolite

Since ancient times, plants have been used as a remedy for numerous diseases. The pharmacological properties of plants are due to the presence of secondary metabolites like terpenoids, flavonoids, alkaloids, etc. Anthraquinones represent a group of naturally occurring quinones found generously across various plant species. Anthraquinones attract a significant amount of attention due to their reported efficacy in treating a wide range of diseases. Their complex chemical structures, combined with inherent medicinal properties, underscore their potential as agents for therapy. They demonstrate several therapeutic properties such as laxative, antitumor, antimalarial, antibacterial, antifungal, antioxidant, etc. Anthraquinones are found in different forms (derivatives) in plants, and they exhibit various medicinal properties due to their structure and chemical nature. The precursors for the biosynthesis of anthraquinones in higher plants are provided by different pathways such as plastidic hemiterpenoid 2-C-methyl-D-erthriol4-phosphate (MEP), mevalonate (MVA), isochorismate synthase and polyketide. Anthraquinones possess several medicinal properties and a complex biosynthetic pathway, making them good candidates for patenting new products, synthesis methods, and biotechnological production advancements. By conducting a thorough analysis of scientific literature, this review provides insights into the intricate interplay between anthraquinone biosynthesis and its broad-ranging contributions to human health.

Volatile metabolomics and transcriptomics analyses provide insights into the mechanism of volatile changes during fruit development of 'Ehime 38' (Citrus reticulata) and its bud mutant

Volatile compounds are important determinants affecting fruit flavor. Previous study has identified a bud mutant of 'Ehime 38' (Citrus reticulata) with different volatile profile. However, the volatile changes between WT and MT during fruit development and underlying mechanism remain elusive. In this study, a total of 35 volatile compounds were identified in the pulps of WT and MT at five developmental stages. Both varieties accumulated similar and the highest levels of volatiles at stage S1, and showed a downward trend as the fruit develops. However, the total volatile contents in the pulps of MT were 1.4-2.5 folds higher than those in WT at stages S2-S5, which was mainly due to the increase in the content of d-limonene. Transcriptomic and RT-qPCR analysis revealed that most genes in MEP pathway were positively correlated with the volatile contents, of which DXS1 might mainly contribute to the elevated volatiles accumulation in MT by increasing the flux into the MEP pathway. Moreover, temporal expression analysis indicated that these MEP pathway genes functioned at different developmental stages. This study provided comprehensive volatile metabolomics and transcriptomics characterizations of a citrus mutant during fruit development, which is valuable for fruit flavor improvement in citrus.

A review of the types, functions and regulatory mechanisms of plant spines

Over a long period of evolution, plants have developed self-protection mechanisms, such as leaving seeds, dropping leaves, growing thorns, producing specific substances or emitting special odors to repel insects. Although studies on the taxonomic characteristics, functions and application of spines in spiny plants have been reported in China and abroad, a systematic overview of plant spines is currently lacking. This study therefore identifies the characteristics and types of plant spines based on domestic and international research on plant spines to provide clear criteria or bases for determining the types of plant spines. In addition, the functions, regulatory mechanisms, and factors influencing the formation of spines and the prospects for their development and application are described and summarized. This study will help to improve the understanding of the types, functions and regulatory mechanisms of plant spines and provide new ideas for the genetic improvement of plants from spiny to nonspiny varieties.

Genotype-Specific Expression of Selected Candidate Genes Conferring Resistance to Leaf Rust of Rye (Secale cereale L.)

Leaf rust (LR) caused by Puccinia recondita f. sp. secalis (Prs) is a highly destructive disease in rye. However, the genetic mechanisms underlying the rye immune response to this disease remain relatively uncharacterised. In this study, we analysed the expression of four genes in 12 rye inbred lines inoculated with Prs at 20 and 36 h post-treatment (hpt): DXS (1-deoxy-D-xylulose 5-phosphate synthase), Glu (β-1,3-glucanase), GT (UDP-glycosyltransferase) and PR-1 (pathogenesis-related protein 1). The RT-qPCR analysis revealed the upregulated expression of the four genes in response to Prs in all inbred lines and at both time-points. The gene expression data were supported by microscopic and macroscopic examinations, which revealed that eight lines were susceptible to LR and four lines were highly resistant to LR. A relationship between the infection profiles and the expression of the analysed genes was observed: in the resistant lines, the expression level fold changes were usually higher at 20 hpt than at 36 hpt, while the opposite trend was observed in the susceptible lines. The study results indicate that DXS, Glu, GT and PR-1 may encode proteins crucial for the rye defence response to the LR pathogen.

Food Perception: Taste, Smell and Flavour

Flavor is the most important sensory quality in food [...].

Transcriptome Analyses Reveal the Aroma Terpeniods Biosynthesis Pathways of Primula forbesii Franch. and the Functional Characterization of the PfDXS2 Gene

Primula forbesii Franch. is a unique biennial herb with a strong floral fragrance, making it an excellent material for studying the aroma characteristics of the genus Primula. The floral scent is an important ornamental trait that facilitates fertilization. However, the molecular mechanism regulating the floral scent in Primula is unknown. In order to better understand the biological mechanisms of floral scents in this species, this study used RNA sequencing analysis to discuss the first transcriptome sequence of four flowering stages of P. forbesii, which generated 12 P. forbesii cDNA libraries with 79.64 Gb of clean data that formed 51,849 unigenes. Moreover, 53.26% of the unigenes were annotated using public databases. P. forbesii contained 44 candidate genes covering all known enzymatic steps for the biosynthesis of volatile terpenes, the major contributor to the flower's scent. Finally, 1-deoxy-d-xylulose 5-phosphate synthase gene of P. forbesii (PfDXS2, MK370094), the first key enzyme gene in the 2-c-methyl-d-erythritol 4-phosphate (MEP) pathway of terpenoids, was cloned and functionally verified using virus-induced gene silencing (VIGs). The results showed that PfDXS2-silencing significantly reduced the relative concentrations of main volatile terpenes. This report is the first to present molecular data related to aroma metabolites biosynthesis pathways and the functional characterization of any P. forbesii gene. The data on RNA sequencing provide comprehensive information for further analysis of other plants of the genus Primula.