Abstract: A method for determining tobacco-specific nitrosamines (TSNAs) in cigarette smoke using one-step clean-up coupled with LC-MS/MS is provided, including the following steps: collecting a particulate matter of mainstream cigarette smoke with a Cambridge filter pad, mixing the particulate matter of mainstream cigarette smoke, an internal standards solution and water in a 50 mL plastic centrifuge tube, and vortexing the resulting mixture at room temperature to allow extraction; transferring an extraction solution after filtration to a new centrifuge tube, adding dichloromethane, and vortexing the resulting mixture; centrifuging to collect a dichloromethane extraction solution in a lower layer to another centrifuge tube, and placing the centrifuge tube in a water bath to remove dichloromethane; dissolving the resulting extraction solution in water, and transferring the resulting solution to an autosampler vial for LC-MS/MS analysis.

Abstract: A method for determining tobacco-specific nitrosamines (TSNAs) in tobacco using one-step clean-up coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) is provided, including the following steps: destemming flue-cured tobacco or sun-cured tobacco, drying, milling, and passing through a sieve; mixing the resulting tobacco, an internal standards solution and water in a plastic centrifuge tube, and vortexing the resulting mixture at room temperature to allow extraction; transferring an extraction solution after filtration to a new centrifuge tube, adding dichloromethane, and vortexing the resulting mixture; centrifuging to collect a dichloromethane extraction solution in a lower layer to another centrifuge tube, and placing the centrifuge tube in a water bath to remove dichloromethane; dissolving the resulting extraction solution in water, and transferring the resulting solution to an autosampler vial for LC-MS/MS analysis.

Abstract: A method for identifying converters from tobacco seedling population. The method includes: 1) sowing and cultivating tobacco seeds to be identified for 45-55 days; sampling a plurality of leaf disks from each of 45-55 days old seedlings; 2) incubating the plurality of leaf disks of each seedling in a sealed container at 37° C. for 10-12 hours, thereby obtaining a plurality of incubated tobacco leaves of each seedling; 3) immersing the plurality of incubated tobacco leaves of each seedling in an extractant, extracting alkaloids and obtaining an extract of each seedling; 4) analyzing the amounts of nicotine and nornicotine in the alkaloids extract of each seedling; and 5) automatically recognizing peaks of the alkaloids extract of each seedling, and calculating the percent nicotine conversion (PNC) and the pseudo percent nicotine conversion (PPNC).

Abstract: The disclosure provides a method of screening tobacco germplasm for resistance to Alternaria alternata by ripening seedling leaves. The method includes ripening seedling leaves, spray inoculation, disease induction, and evaluation of disease resistance. Dense planting, fertilizer control, and potassium increment were used to forcibly ripening seedling leaves. A hospitable environment was simulated to induce disease in the ripened leaves. These treatments reduce differences in leaf maturity and avoid environmental changes. The technique of the disclosure provides greater accuracy and repeatability than the current technique of screening brown spot resistance, and offers the advantages of simple operation, reduced cost, space requirement, and labor intensity, high selection efficiency, and an accurate screening of tobacco phenotypes with resistance to brown spot, etc., used for large-scale screening of tobacco varieties with resistance to brown spot.

Abstract: A TMV resistant tobacco plant containing a short N introgressed segment and a method for breeding the same. A homozygous tobacco plant containing an N introgressed segment is hybridized with a tobacco plant of genotype nn to obtain an F1 progeny tobacco plant of genotype Nn. The F1 progeny tobacco plant is hybridized with the tobacco plant of genotype nn, to obtain population materials for screening to obtain the short N introgressed segment. TMV is inoculated at a seedling stage, and Nn genotype plants showing necrotic lesion are obtained by screening the population materials. The Nn genotype plants are genotyped using a molecular marker TN5.51 primer pair and an N gene-specific molecular marker N1N2 at the right end of the N introgressed segment. A plant found to be negative when tested by the TN5.51 primer pair and to be positive when tested by the N1N2 molecular marker is a plant comprising the short N introgressed segment.

Abstract: The invention relates to the isolation and the cloning and breeding application of a tobacco mosaic virus (TMV) resistant N?au gene. The invention discloses the nucleotide sequence of the TMV resistant N?au gene shown as SEQ ID NO.1. The amino acids of polypeptide encoded by the TMV resistant N?au gene are shown as SEQ ID NO.2. A non-transgenic TMV resistant tobacco variety can be obtained by transferring an N?au gene which is contained by germplasm resources into a TMV infected popular tobacco variety by conventional breeding means. The N?au gene of the invention has a homologous sequence with high identity rate of nucleotides in the popular tobacco variety, so that it is easy to obtain a shorter introgression segment single plant carrying the N?au gene by conventional breeding, and thereby to obtain a TMV resistant variety with lower linkage drag. The gene can resist both U1 strain and Cg strain of TMV.

Abstract: The invention relates to the isolation and the cloning and breeding application of a tobacco mosaic virus (TMV) resistant N'au gene. The invention discloses the nucleotide sequence of the TMV resistant N'au gene shown as SEQ ID NO.1. The amino acids of polypeptide encoded by the TMV resistant N'au gene are shown as SEQ ID NO.2. A non-transgenic TMV resistant tobacco variety can be obtained by transferring an N'au gene which is contained by germplasm resources into a TMV infected popular tobacco variety by conventional breeding means. The N'au gene of the invention has a homologous sequence with high identity rate of nucleotides in the popular tobacco variety, so that it is easy to obtain a shorter introgression segment single plant carrying the N'au gene by conventional breeding, and thereby to obtain a TMV resistant variety with lower linkage drag. The gene can resist both U1 strain and Cg strain of TMV.