Abstract: In order to study the effect of post ripening treatment on the baking quality of upper leaves of flue‑cured tobacco and improve the availability of upper leaves，in this study，the upper leaves of normal treatment（CK），12 h post ripening treatment（H1），24 h post ripening treatment（H2）and 36 h post ripening treatment（H3）were used as test materials.The effects of post ripening treatment on the baking quality of upper leaves were analyzed from the aspects of cell biology and molecule by using transmission electron microscope and qRT‑PCR. The main results were as follows：（1）Compared with the normal treated tobacco leaves，the browning speed and degree of post ripening treated tobacco leaves in H2 decreased during the curing process，the proportion of medium and high grade tobacco increased，the proportion of mild browning tobacco leaves decreased by 34.39%，the proportion of moderate and above browning decreased by 43.02%，and the proportion of high‑grade tobacco increased by 17.29%.（2）After post ripening，the tissue structure of upper leaves was loose and the number of starch granules decreased；The contents of reducing sugar and total sugar in flue‑cured tobacco treated with H2 increased by 53.33% and 16.33% respectively，and the starch content in flue‑cured tobacco treated with H3 decreased by 5.61%.The results showed that the macromolecular substances in the upper leaves of post ripening treatment were degraded greatly，and the internal chemical components were more coordinated.（3）The activity of ester‑oxygenase（LOX） in post ripening tobacco leaves increased significantly，and the content of fatty acids decreased significantly.The results showed that the maturity of post ripening tobacco leaves was improved，and the content of lipid metabolism substrate was reduced during the curing process，and the degree of browning was reduced.（4）The expression analysis of key genes of glucose metabolism and lipid metabolism showed that the expressions of lipid transporter gene 1（LTP1），MYB family gene 48（MYB48），wax synthesis gene 10（CER10），sucrose synthase gene（SS），sucrose invertasegene（INV） and pyrophosphorylase gene（AGP） in post ripening tobacco weresignificantly down regulated.The results showed that the sugar metabolism and lipid synthesis of postripening tobacco leaves were inhibited during curing，which had a positive effect on the inclusions and color changes of upper leaves during curing.

Key words: Flue?cured tobacco, Post ripening technology, Upper leaf, Maturity, Browning, Sugar metabolism, Lipid metabolism

摘要： 为研究后熟处理对烤烟上部叶烘烤品质的影响，提高上部叶可用性，以正常处理（CK）、12 h后熟处理（H1）、24 h后熟处理（H2）、36 h后熟处理（H3）的上部叶为供试材料，利用透射电镜和荧光定量PCR（qRT-PCR）等技术从细胞生物学和分子层面分析后熟处理对上部叶烘烤品质的影响。结果显示：（1）与正常处理烟叶相比，后熟处理烟叶在烘烤过程中褐变速度减缓、褐变程度减轻，烤后烟中上等烟比例提高，H2 处理轻度褐变烟叶比例下降34.39%，中度及以上褐变比例下降43.02%，上等烟比例提高17.29%。（2）后熟处理上部叶组织结构较松散，淀粉粒数量降低；H2处理烤后烟叶还原糖和总糖含量分别提高53.33%和16.33%，H3处理淀粉含量降低5.61%。表明后熟处理上部叶大分子物质大量降解，内在化学成分更协调。（3）后熟处理烟叶脂氧合酶（LOX）活性显著增加，脂肪酸含量显著下降。表明后熟处理烟叶的成熟度提高，同时减少了烘烤过程中脂质代谢底物的含量，褐变程度降低。（4）糖代谢及脂质代谢关键基因表达分析结果显示，后熟处理烟叶中脂质转运蛋白基因1（LTP1）、MYB家族基因48（MYB48）、蜡质合成基因10（CER10）、蔗糖合成酶基因（SS）、蔗糖转化酶基因（INV）和焦磷酸化酶基因（AGP）的表达量均显著下调。表明后熟处理烟叶在烘烤过程中糖代谢和脂质合成均受到抑制，对烤烟上部叶烘烤过程中的内含物和颜色变化具有正向影响。

关键词: 烤烟, 后熟技术, 上部叶, 成熟度, 褐变, 糖代谢, 脂质代谢