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The loop-mediated isothermal amplification (LAMP) primers were designed for the conserved region of the selected Nicotiana-specific gene Ntsp151 sequence, and a visual LAMP detection method for tobacco materials based on the SYBR Green I was established. The genomic DNA extraction method and reaction conditions were optimized in the detection process. Furthermore, the specificity and sensitivity of the LAMP reaction system were evaluated. The results showed that the genomic DNA extracted by Chelex-100 could be directly amplified and fluorescently colored by LAMP; the optimal reaction conditions of the LAMP primers were amplification temperature 63 °C, reaction time 60 min, Mg2+ concentration 6 mmol/L; LAMP detection method had good specificity and the results of chromogenic amplification and fluorescence detection of 17 non-tobacco materials and 1 tobacco material were consistent and had good specificity. The sensitivity test showed that the minimum detection limit of the LAMP reaction system was 102 copies/μL. The LAMP detection based on Nicotiana-specific gene Ntsp151 was result-visualized, highly sensitive, and specific, which was suitable for field inspection. [ABSTRACT FROM AUTHOR]

In order to develop high quality reconstituted tobacco for heated tobacco products, bacterial cellulose (BC) obtained by fermentation using tobacco leaves combined with tobacco extracts and tobacco filter residues were mixed to prepare BC reconstituted tobacco based on whole tobacco components. The BC reconstituted tobacco was compared with three typical commercial reconstituted tobacco products for heated tobacco products. A systematic analysis was carried out in terms of appearance, microstructure, main chemical components, thermogravimetric properties and pyrolyzed aroma products. The results showed that: 1) BC reconstituted tobacco had a good formability with uniform appearance, and its physical indicators were close to those of commercial slurry processed reconstituted tobacco products. 2) Compared with the three typical reconstituted tobacco products, BC reconstituted tobacco had similar infrared absorption, however, BC reconstituted tobacco had a dense structure and the diameter of BC fibers was 43.68-75.80 nm under scanning electron microscope. 3) The total heat absorption of BC reconstituted tobacco was the largest and up to 9.52 J·g-1. 4) The sugar content in BC reconstituted tobacco was 6.17% and the nicotine content reached 13.17 mg·g-1, and the pyrolysis of BC reconstituted tobacco released 45 kinds of aroma substances, in which the releases of ketone-aldehyde aroma substances were significantly higher than those of the control samples. [ABSTRACT FROM AUTHOR]

SUMMARY UV‐B radiation can induce the accumulation of many secondary metabolites, including flavonoids, in plants to protect them from oxidative damage. BRI1‐EMS‐SUPPRESSOR1 (BES1) has been shown to mediate the biosynthesis of flavonoids in response to UV‐B. However, the detailed mechanism by which it acts still needs to be further elucidated. Here, we revealed that UV‐B significantly inhibited the transcription of multiple transcription factor genes in tobacco, including NtMYB27, which was subsequently shown to be a repressor of flavonoids synthesis in tobacco. We further demonstrated that NtBES1 directly binds to the E‐box motifs present in the promoter of NtMYB27 to mediate its transcriptional repression upon UV‐B exposure. The UV‐B‐repressed NtMYB27 could bind to the ACCT‐containing element (ACE) in the promoters of Nt4CL and NtCHS and served as a modulator that promoted the biosynthesis of lignin and chlorogenic acid (CGA) but inhibited the accumulation of flavonoids in tobacco. The expression of NtMYB27 was also significantly repressed by heat stress, suggesting its putative roles in regulating heat‐induced flavonoids accumulation. Taken together, our results revealed the role of NtBES1 and NtMYB27 in regulating the synthesis of flavonoids during the plant response to UV‐B radiation in tobacco. [ABSTRACT FROM AUTHOR]

Background: Citrus products often suffer from delayed bitterness, which is generated from the conversion of non-bitter precursors (limonoate A-ring lactone, LARL) to limonin under the catalysis of limonin D-ring lactone hydrolase (LDLH). In this study, LDLH was isolated and purified from sweet orange seeds, and a rapid and accurate high-performance liquid chromatography method to quantify LARL was developed and applied to analyze the activity and enzymatic properties of purified LDLH., Results: Purified LDLH (25.22 U mg -1 ) showed bands of 245 kDa and 17.5 kDa molecular weights in native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE analysis respectively. After a 24 h incubation under strongly acidic (pH 3) or strongly alkaline (pH 9) conditions, LDLH still retained approximately 100% activity. Moreover, LDLH activity was not impaired by thermal treatment at 50 °C for 120 min. Enzyme inhibition assays showed that LDLH was inactivated only after ethylenediaminetetraacetic acid treatment, and other enzyme inhibitors showed no significant effect on its activity. In addition, the LDLH activity of calcium ion (Ca 2+ ) intervention was 108% of that in the blank group, and that of zinc ion (Zn 2+ ) intervention was 71%., Conclusion: LDLH purified in this study was a multimer containing 17.5 kDa monomer with a wide pH tolerance range (pH 3-9) and excellent thermal stability. Moreover, LDLH might be a metallopeptidase, and its activity was stimulated by Ca 2+ and significantly inhibited by Zn 2+ . These findings improve our understanding of LDLH and provide some important implications for reducing the bitterness in citrus products in the future. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

A series of specimens with some differences in wing patterns and male genitalia from different localities is recognized as Halpe paupera Devyatkin, 2002 by comparing the COI gene sequences. The morphological variability in male is discussed and illustrated. The intraspecific variation of the female of H. paupera walthewi Devyatkin, 2002 from the type locality is elucidated, and hence this subspecies is considered a synonym of H. paupera paupera. A distribution map and some bionomic information of the species are provided.

2-Phenylethanol (2- PE) is an aromatic alcohol with wide applications, but there is still no efficient microbial cell factory for 2-PE based on Escherichia coli. In this study, we constructed a metabolically engineered E. coli capable of de novo synthesis of 2-PE from glucose. Firstly, the heterologous styrene-derived and Ehrlich pathways were individually constructed in an L-Phe producer. The results showed that the Ehrlich pathway was better suited to the host than the styrene-derived pathway, resulting in a higher 2-PE titer of ∼0.76 ± 0.02 g/L after 72 h of shake flask fermentation. Furthermore, the phenylacetic acid synthase encoded by feaB was deleted to decrease the consumption of 2-phenylacetaldehyde, and the 2-PE titer increased to 1.75 ± 0.08 g/L. As phosphoenolpyruvate (PEP) is an important precursor for L-Phe synthesis, both the crr and pykF genes were knocked out, leading to ∼35% increase of the 2-PE titer, which reached 2.36 ± 0.06 g/L. Finally, a plasmid-free engineered strain was constructed based on the Ehrlich pathway by integrating multiple ARO10 cassettes (encoding phenylpyruvate decarboxylases) and overexpressing the yjgB gene. The engineered strain produced 2.28 ± 0.20 g/L of 2-PE with a yield of 0.076 g/g glucose and productivity of 0.048 g/L/h. To our best knowledge, this is the highest titer and productivity ever reported for the de novo synthesis of 2-PE in E. coli. In a 5-L fermenter, the 2-PE titer reached 2.15 g/L after 32 h of fermentation, suggesting that the strain has the potential to efficiently produce higher 2-PE titers following further fermentation optimization., (© The Author(s) 2022. Published by Oxford University Press on behalf of Society of Industrial Microbiology and Biotechnology.)