关键词: 烤烟, 烘烤特性, 淀粉, 糖, 酶活性, 基因表达

Abstract: In order to identify the effects of different water loss treatments on starch metabolism in postharvest tobacco leaves, taking  Qinyan 96 as the material  this experiment set up three water loss treatments of normal treatment (CK), water loss 10% (T1) and water loss 20% (T2) to study the baking characteristics of postharvest tobacco leaves and the dynamic changes in the enzyme activity and gene expression related to starch metabolism. The results showed that: Compared with normal treatment, water loss treatment shortened the yellowing time of tobacco leaves, and the time of browning was affected. Under water loss treatment, amylose degradation of postharvest tobacco leaves was mainly concentrated in the early stage (0～18 h) while the degradation of amylopectin mainly concentrated in the late stage (after 18 h), and the total starch content of tobacco leaves decreased after water treatment. Because of the decline of DBE enzyme activity and SBE enzyme activity with the increase of postharvest time, and the corresponding enzyme genes expression level decreased (except SBE), therefore, the synthesis of postharvest tobacco starch was inhibited. However, the activity of amylase increased with the prolongation of postharvest time, the corresponding enzyme genes expression level increased, which promoted the increase of total sugar and reducing sugar content in postharvest tobacco leaves. In summary, water loss treatment improved the baking characteristics of tobacco leaves, the degradation ability of starch was enhanced and increased sugar content in postharvest tobacco, and 10% water loss treatment had the best effect. The degradation of postharvest tobacco amylose was mainly concentrated in the early postharvest (0～18 h), and amylopectin was mainly concentrated in the later stage(18～36 h).

Key words: flue-cured tobacco, baking characteristics, starch, sugar, enzyme activity, gene expression