Comparison Analysis of Glandular Trichomes Morphology and Secretion Characteristics among Different Flue-cured Tobacco Varieties in Luoyang Tobacco-planting Area

Using cultivars(lines) including Heluo 1, LY100, Yunongxiang 201, Zhongyan 100(ZY100), K326, and Yunyan 87(YY87) as materials, a comparative analysis was conducted on the morphological structure of trichomes, leaf surface chemical components, and the expression levels of genes related to trichome development and metabolism in a typical ecological region of Luoyang. The results showed that the leaf surface trichomes of all cultivars comprised three types: long glandular trichomes, short glandular trichomes and protective trichomes, but their proportions varied. Except for ZY100, long glandular trichomes were predominant in the other cultivars. Trichome density differed significantly among cultivars and changed during leaf development. K326 exhibited the highest trichome density, followed by Yunongxiang 201, while ZY100 had the lowest. The trichome secretions primarily consisted of cembratrien-diols(CBT-diols), sucrose esters and hydrocarbons, with CBT-diols being the major component, accounting for 73.49% to 84.54% of the total. The content of sucrose esters was relatively low, accounting for only 4.34% to 7.74%. The total secretions content was the highest in K326, followed by Yunongxiang 201, while ZY100 was the lowest. The expression levels of trichome development-related genes NtMIXTA, NtWo and NtHD9 were the highest in Yunongxiang 201, whereas NtCycB2 was highly expressed in ZY100. Key genes involved in secretions synthesis, NtCBT, NtCBT and NtASAT1, showed high expression in Yunongxiang 201 and low expression in ZY100.