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The phenomenon of oxygen incorporation-induced superconductivity in iron telluride (Fe1+yTe, with antiferromagnetic (AFM) orders) is intriguing and quite different from the case of FeSe. Until now, the microscopic origin of the induced superconductivity and the role of oxygen are far from clear. Here, by combining in situ scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoemission spectroscopy (XPS) on oxygenated FeTe, we found physically adsorbed O2 molecules crystallized into c (2/3 × 2) structure as an oxygen overlayer at low temperature, which was vital for superconductivity. The O2 overlayer were not epitaxial on the FeTe lattice, which implied weak O2 –FeTe interaction but strong molecular interactions. The energy shift observed in the STS and XPS measurements indicated a hole doping effect from the O2 overlayer to the FeTe layer, leading to a superconducting gap of 4.5 meV opened across the Fermi level. Our direct microscopic probe clarified the role of oxygen on FeTe and emphasized the importance of charge transfer effect to induce superconductivity in iron-chalcogenide thin films.

Nornicotine production in Nicotiana tabacum is undesirable because it is the precursor of the carcinogen N′-nitrosonornicotine. In some individual burley tobacco plants, a large proportion of the nicotine can be converted to nornicotine, and this process of nicotine conversion is mediated primarily by enzymatic N-demethylation of nicotine which is controlled mainly by CYP82E4. Here we report a novel strategy based on quantitative real-time polymerase chain reaction (qPCR) method, which analyzed the ratio of nicotine conversion through examining the transcript level of CYP82E4 in burley leaves and do not need ethylene induction before detected. The assay was linear in a range from 1 × 101 to 1 × 105 copies/mL of serially diluted standards, and also showed high specificity and reproducibility (93%–99%). To assess its applicability, 55 plants of burley cultivar Ky8959 at leaf maturing stage were analyzed, and the results were in accordance with those from gas chromatograph-mass spectrometry (GC-MS) method. Moreover, a linear correlation existed between conversion level and CYP82E4 transcript abundance. Taken together, the quantitative real-time PCR assay is standardized, rapid and reproducible for estimation of nicotine conversion level in vivo, which is expected to shed new light on monitoring of burley tobacco converter.

In this study, we report the isolation and purification of protoplasts from Chinese kale (Brassica oleracea var. alboglabra) hypocotyls, and their transient gene expression transformation and subcellular localization of BaMYB75 (Bol042409). The upshot is that the vintage protocol included 5-d hypocotyls that were enzymatically hydrolyzed for 8 h in enzyme solution (3.0% cellulase, 0.5% pectolase, and 0.5 M mannitol), and the protoplasts were purified by precipitation. The total yield of protoplasts was 8 × 105 protoplast g−1 fresh weight, and the protoplasts’ viability was 90%. The maximum transformation efficiency obtained by using green fluorescent protein (GFP) as a detection gene was approximately 45% when the polyethylene glycol (PEG)4000 concentration was 40% and transformation time was 20 min. In addition, BaMYB75 was ultimately localized in the nucleus of Chinese kale hypocotyl protoplasts, verifying the validity and reliability of this transient transformation system. An effective and economical hypocotyl protoplast isolation, purification, and transformation system was established for Chinese kale in this study. This effectively avoided interference of chloroplast autofluorescence compared to using mesophyll cells, laying the foundation for future research in the molecular biology of Brassica vegetables.

To increase the understanding of alkaloid biosynthesis in Nicotiana tabacum during whole plant growth periods, variations of the contents of alkaloids and the transcription of key biosynthetic genes in fresh leaves were investigated in three varieties at five developmental stages. Six alkaloids were analyzed by gas chromatograph–mass spectrometry (GC–MS) and the most abundant alkaloid was observed during the upper leaves maturing stage in the varieties, among which the alkaloid content of K326 was the highest. Considering the genetic effect, variance analysis indicated that the developmental stage played a predominant role in alkaloid accumulation. Moreover, the levels of biosynthetic gene transcripts in the leaves at the vigorous growing stage might contribute to the contents of alkaloids in the leaves during the maturing stages. To further illuminate the metabolism of alkaloid biosynthesis, a correlation among alkaloids was also documented.

‘Hongmian miyou’ (Citrus grandis L. Osbeck) is mutated from ‘Guanxi miyou’, with a different spongy layer coloration. Trifoliate orange (Poncirus trifoliata) is widely used as rootstocks in ‘Guanxi miyou’ grafting, whereas ‘Hongmian miyou’ is incompatible with available trifoliate orange rootstocks. To explore the reasons for the etiolation of leaves of ‘Hongmian miyou’/trifoliate orange, anatomical differences among different graft unions, gene expression profiles, and auxin levels of scion were investigated in this study. A histological assay indicated that there was no significant difference in anatomical structure between the compatible and incompatible combinations. A total of 1950 significant differentially-expressed genes (DEGs) were identified and analyzed. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that genes involved in carbohydrate metabolism, energy metabolism, amino acid metabolism, and plant hormone signal transduction were significantly enriched. Moreover, the expression of nine genes in the auxin pathway were upregulated and three were downregulated in compatible combinations compared with those in the incompatible group. Further experiments verified that indole-3-acetic acid (IAA) content increases in the compatible graft combination, which suggests that IAA might promote graft compatibility.

In this study, we report the isolation and purification of protoplasts from Chinese kale (Brassica oleracea var. alboglabra) hypocotyls, and their transient gene expression transformation and subcellular localization of BaMYB75 (Bol042409). The upshot is that the vintage protocol included 5-d hypocotyls that were enzymatically hydrolyzed for 8 h in enzyme solution (3.0% cellulase, 0.5% pectolase, and 0.5 M mannitol), and the protoplasts were purified by precipitation. The total yield of protoplasts was 8 × 10 5 protoplast g -1 fresh weight, and the protoplasts' viability was 90%. The maximum transformation efficiency obtained by using green fluorescent protein (GFP) as a detection gene was approximately 45% when the polyethylene glycol (PEG)4000 concentration was 40% and transformation time was 20 min. In addition, BaMYB75 was ultimately localized in the nucleus of Chinese kale hypocotyl protoplasts, verifying the validity and reliability of this transient transformation system. An effective and economical hypocotyl protoplast isolation, purification, and transformation system was established for Chinese kale in this study. This effectively avoided interference of chloroplast autofluorescence compared to using mesophyll cells, laying the foundation for future research in the molecular biology of Brassica vegetables., Competing Interests: The authors declare no conflict of interest.