Effects of Exogenous Zeatin on Contents of Nicotine and Endogenous Hormones and Expression of Nicotine Synthesis Related Genes in Tobacco Leaves

Zheng Yanfeng; Zhang Jingyao; Wu Guizhi; Meng Jun; Chen Gang; Tan Yongyan; Liu Renxiang

doi:10.14083/j.issn.1001-4942.2025.01.006

Abstract：In order to investigate the effects of exogenous zeatin on nicotine content,endogenous hor-mones contents,and gene expression related to nicotine synthesis in tobacco leaves,this study set three spray concentrations of zeatin(1,2 and 3 mg/L)with equal amount of water as control.Foliar spraying was carried out on the day of topping the tobacco plants,and the agronomic traits of tobacco plants and nicotine content,endogenous hormones contents and expression levels of key genes related to nicotine synthesis in leaves were measured at 5,10 and 15 days after treatment.The results showed that compared with the control,spraying different concentrations of exogenous zeatin had no significant effect on agronomic traits of tobacco plants.The nicotine content in tobacco leaves significantly decreased,and the most significant decrease occurred on the 5th day after spraying with a reduction of 20.58％,31.76％and 28.74％,respectively.The contents of zeatin(ZR),auxin(IAA)and gibberellin(GA)significantly increased with an increase range of 21.63％to 41.68％,13.94％to 87.49％,and 10.56％to 47.32％,respectively.The content of abscisic acid(ABA)sig-nificantly decreased with a reduction of 4.34％to 72.70％.The expression levels of NtPMT,NtODC and NtM-PO were significantly downregulated.NtPMT and NtMPO were most significantly downregulated at 10 days af-ter treatment with a decrease of 26.82％,55.59％,62.88％and 31.22％,36.97％,45.75％in treatment T1,T2 and T3,respectively,compared to control.NtODC was most significantly downregulated at 5 days after treatment with a decrease of 36.30％,77.26％and 53.34％in treatment T1,T2 and T3,respectively,com-pared to control.Above all,foliar spraying of zeatin on the day of topping had no significant effect on tobacco growth,but had significant impacts on endogenous hormone levels in tobacco leaves,thereby affecting the ex-pression of nicotine synthesis related genes and significantly reducing nicotine content in tobacco leaves.A-mong them,spraying 2 mg/L zeatin had a better regulatory effect.This study could provide the theoretical ba-sis and technical support for regulation of nicotine content in tobacco production.