Analysis of Grafting Effect of Low Nicotine Flue-cured Tobacco Varieties and Eggplant and Its Influence on Nicotine Synthesis on Grafting Surface

BAI Yafan; ZHANG Mengyue; LI Yan; ZHAO Yuanyuan; SHI Sujuan; SHI Hongzhi

doi:10.15933/j.cnki.1004-3268.2024.10.007

Abstract：Reducing the nicotine content of tobacco leaves to a level below the threshold of addiction is a measure proposed by the World Health Organization to reduce people's dependence on tobacco,but the nicotine content of existing low-nicotine varieties can not meet the preliminary standards proposed by the World Health Organization.This study explored the effect and feasibility of grafting low nicotine varieties with eggplant to reduce nicotine content,the key genes of nicotine synthesis on grafting surface were identified by PCR,and the sources of trace alkaloids in grafted tobacco leaves and their responses to varieties with different nicotine content were analyzed.The results showed that the nicotine content in middle leaves of flue-cured tobacco leaves of imported low-nicotine variety NC926 and domestic low-nicotine variety LAK326(CD-01)was 0.251 3%and 0.272 0%respectively.After grafting NC926 with eggplant,the nicotine content in fresh tobacco leaves and middle leaves of flue-cured tobacco leaves decreased to 0.039 5%and 0.046 0%respectively.After grafting LAK326 with eggplant,the nicotine content in fresh tobacco leaves and flue-cured tobacco leaves decreased to 0.037 0%and 0.039 4%respectively,which was close to or lower than the standard of 0.4 mg/g set by the World Health Organization.By comparing the expression of the key genes NtPMT1,NtPMT2,NtQPT2,NtBBLa,NtA622 of nicotine synthesis on the grafted surface of conventional high nicotine varieties and low nicotine varieties with those on the stem surface of non-grafted tobacco,it was found that the key genes of nicotine synthesis in the stem surface of high nicotine and low nicotine varieties were significantly up-regulated in different degrees after grafting,indicating that grafting measures could induce the ability of nicotine synthesis in the grafted part.It was speculated that the trace nicotine in grafted tobacco came from stem section.Moreover,varieties with different nicotine synthesis ability had different responses to grafting,and the expression of key genes of nicotine synthesis in low nicotine varieties was lower than that in high nicotine varieties.To sum up,compared with conventional high nicotine varieties grafted with eggplant,the combination of low nicotine varieties and eggplant grafting technology can further reduce the nicotine content of tobacco leaves,and the cured tobacco leaves can be close to or lower than the nicotine content limit standard set by the World Health Organization.