酮生物合成路径及其关键酶的研究进展

酮是一种特殊的黄酮类化合物,也是藏药中含量最高、生物活性较强、药用价值和经济价值丰富的一类有效成分。目前认为,3-羟基苯甲酸辅酶A连接酶、二苯甲酮合成酶和酮合成酶是酮生物合成路径中的关键酶。文章对酮的结构类型、功能及其在植物中的分布,以及酮的生物合成路径与关键酶进行综述,并对相关研究进行了展望。

Germination Characteristics and Secondary Metabolism Regulation of Scutellaria baicalensis Georgi Seeds under Different Light Intensities

[Objective] This study aimed to investigate the primary and secondary metabolisms during the germination of Scutellaria baicalensis Georgi seeds under different light intensities. [Method] The activities of CHL, soluble sugar, PAL, C4H and CHS were determined with ultraviolet spectrophotometry. The secondary metabolites were detected by High Performance Liquid Chromatography （HPLC）. [Result] The results indicate that the germination of Scutellaria baicalensis Georgi seeds is not sensitive to light and the seedlings were very sensitive to light. The CHL, soluble sugar, PAL, C4H and CHS continuously increased with light intensity. The content of secondary metabolites also increased. [Conclusion] Light increased the formation of leaf photosynthetic pigment, thereby affecting the primary metabolites. The activities of PAL, C4H and CHS significantly increased with the development of light intensity. Finally the secondary metabolites of medicinal plants increased sharply. Therefore, the quality of Scutellaria baicalensis Georgi materials can be improved by increasing the light intensity moderately.

Bioinformatics Analysis of Chalconesynthase Gene in Morus

[Objective] This study aimed to explore the molecular mechanism of mulberry pigment metabolism regulation. [Method] Chalconesynthase（CHS） gene was cloned from Morus（Moraceae） in silico. The amino acid sequence, physical and chemical properties, transmembrane structural domain, hydrophobicity/hydrophilicity,subcellular localization, secondary and tertiary structure of protein were predicted and analyzed by bioinformatics tools. [Result] The cDNA sequence of CHS gene was 1 365bp by splicing using the software DNAstar and it contained a complete ORF including 1 170 bp which encoded 389 amino acids. Bioinformatic analysis showed that CHS gene included specific peptide sequence RLMMYQQGCFAGGTVLR of chalcone synthase superfamily, but has no signal peptide, belonging to the non-secretory proteins, located inside of cytoplasm. Its molecular evolution is more conservative.[Conclusion] The results above provided foundation for the further studies of structure and function of CHS protein.

Cloning and Analysis of a Chalone Synthase Gene from Fagopyrum tataricum

[Objective] This study aimed to clone a full-length CHS gene from buck- wheat. [Method] With total RNA extracted from buckwheat as the template, CHS cD- NA sequence was cloned from buckwheat by using RACE technology and CODEHOP primer design method, the full length gene was obtained by primers which were de- signed for amplification of full-length gene sequence with buckwheat DNA template. Clustalxl.81 and MEGA4 software were used for sequence analysis and construction of phylogenetic tree; NCBI Blastn and Biastp programs were applied for homology analysis of nucleic acid and protein. [Result] Bioinformatics analysis showed that the full length of this gene is 1 906 bp, containing a 463 bp intron sequence and a 1 188 bp coding region, encoding 395 amino acids. Blastn sequence alignment revealed that the CHS gene sequence obtained in this study shared 86% homology with the CHS gene of closely related species. [Conclusion] This study laid the foundation to clarify molecular basis of the synthesis of buckwheat bioflavanoids and explore an effective way to improve the content of buckwheat bioflavanoids.

Cloning and Sequence Analysis of CHS Gene Fragment from Acer truncatum

[Objective] This study aimed to clone and analyze the sequence of CHS gene from Acer truncatum leaves. [Method] Using A. truncatum cultivars No.1-6 as experimental materials, total RNA was extracted from A. truncatum leaves with the modified CTAB method. CHS gene sequences were downloaded from the NCBI and aligned by BLAST. Degenerate primers were designed by DNAMAN and Primer- premier5 to amplify the target band. CHS gene fragment was amplified by RT-PCR and ligated to pMD18-T vector. The identified positive colonies were sequenced. [Result] A 1 365 bp fragment was amplified. Sequence analysis suggested that the obtained fragment encoded 365 amino acids and shared above 90% homology to nucleotide sequence of CHS gene from A. palmatum and A. [Conclusion] In this study, CHS gene was successfully cloned from A. truncatum for the first time, which laid the foundation for efficient utilization of CHS gene.

A PKS gene, pks-1, is involved in chaetoglobosin biosynthesis, pigmentation and sporulation in Chaetomium globosum

Chaetomium globosum is one of the most common fungi in nature. It is best known for producing chaetoglobosins; however, the molecular basis of chaetoglobosin biosynthesis is poorly understood in this fungus. In this study, we utilized RNA inter- ference （RNAi） to characterize a polyketide synthase gene, pks-1, in C. globosum that is involved in the production of chaeto- globosin A. When pks-1 was knocked down by RNAi, the production of chaetoglobosin A dramatically decreased. Knock-down mutants also displayed a pigment-deficient phenotype. These results suggest that the two polyketides, melanin and chaetoglobosin, are likely to share common biosynthetic steps. Most importantly, we found that pks-I also plays a critical role in sporulation. The silenced mutants ofpks-1 lost the ability to produce spores. We propose that polyketides may modulate cellular development via an unidentified action. We also suggest that C. globosum pks-1 is unique because of its triple role in melanin formation, chaetoglobosin biosynthesis and sporulation. This work may shed light on chaetoglobosin biosynthesis and indicates a relationship between secondary metabolism and fungal morphogenesis.