Changes In Quality In Tobacco Leaves And Metabonomics Analysis Of Ultra-low Nicotine Tobacco Based On Grafting Of Tobacco With Eggplant

In order to explore the technology of reducing nicotine content in tobacco leaves effectively through grafting technology and the production and availability of low nicotine tobacco leaves,a pot experiment was carried out to study the feasibility of producing very low nicotine tobacco leaves,and the changes in growth and development of tobacco plants,chemical composition of tobacco leaves,quality characteristics of tobacco leaves,smoke parameters of tobacco leaves and the differential metabolites of grafted with eggplant were screened by LC/MS,and analyzed by PCA,OPLS-DA and KEGG metabolic pathway enrichment from 2017-2019 in Xiangcheng County,Xuchang City,Henan Province.The purpose of this study is to provide a new way to reduce and regulate nicotine content selectively through agricultural measures,and to provide theoretical support for the feasibility analysis of ultra-low nicotine content tobacco production.The main results are as follows:1.Tobacco was grafted with eggplant,the botanical characteristics and agronomic characters of tobacco plants did not change significantly,the nicotine content of tobacco leaves decreased to a very low level,the nicotine content of cured tobacco leaves decreased by 95%compared with control,and the nornicotine and anabasine were also decreased,but the proportion of anabasine were decreased less,indicating that anabasine may have certain degree of biosynthesis capacity in leaves,and anatabine contents were not detectable in both fresh leaves and cured leaves.The low nicotine tobacco leaves of graftingwith eggplant were favored by budworms(Heliothis assulta),in the enclosed environment,budwormspreferred ultra-low nicotine tobacco leaves to regular tobacco leaves,and the budworms began to feed on the regular tobacco leaves only after the ultra-low nicotine leaves had been eaten up.Covering soil at the bottom of scion stimulated root production which was able to undergo alkaloid biosynthesis,resulting in a significant increase of nicotine content in the tobacco/eggplant with hilling up compared with the tobacco/eggplant without hilling up.The chlorophyll contents of ultra-low nicotine leaves were significantly higher and matured slower than the control plants,and the contents of amino acid,protein,total nitrogen and starch were increased,and the contents of total sugar,reducing sugar and putrescine were decreased.Ultra-low nicotine content in tobacco leaves grafted with eggplant,the contents of NNN,NNK,NAT and TSNAs were decreased significantly,the NNN,NNK and TSNAs contents of upper leaves tobacco/eggplant without hilling up were 82.713%,79.461%and 68.784%lower than the control tobacco/tobacco,respectively.The NNN,NNK and TSNAs contents of the middle leaf tobacco/eggplant without hilling up were 79.676%,79.799%and 68.6362%lower than the control,but the changes of neutral aroma components content in ultra-low nicotine tobacco leaves were small.The nicotine contents of mainstream cigarette smoke were decreased significantly,and the tobacco/eggplant without hilling up were 94.118%lower than the control,there was no significant difference in total particule matter,dampness,CO,tar in smoke and puff number.There was no significant difference in aroma quality,concentration,irritancy and burning quality,aroma quantity,undesirable taste and after taste were decreased to some extent,and significant reduction in impact.Consumer satisfaction,pleasure,and acceptance were also decreased significantly.2.Analysis of the changes of metabolic pathways after grafting with eggplant by LC/MS technology showed that some metabolic pathways were disturbed.29 metabolites with significant differences were screened,such alkaloids,organic acids,amino acids and their derivatives,of which 17 were up-regulated and 12 were down-regulated.Through the analysis of pathway enrichment by differential metabolites,the most significantly enriched metabolic pathway were Aminoacyl-tRNA biosynthesis,Nicotinate and nicotinamide metabolism,Glycine,serine and threonine metabolism,Pantothenate and CoA biosynthesis,beta-Alanine metabolism;C5-Branched dibasic acid metabolism,Arginine and proline metabolism,Alanine,aspartate and glutamate metabolism,Biosynthesis of alkaloid derived from ornithine,lysine and nicotinic acid,etc.The metabolic pathways of these changes were related to the metabolism of amino acids and alkaloids,and the metabolic pathways of alkaloids and amino acids reached a very significant level,indicating that the grafting of tobacco with eggplant affected the distribution and metabolism of carbon and nitrogen in flue-cured tobacco.3.The results of the study showed that the selective reduction of nicotine content by grafting technology had different effects on the content of chemical components,the quality characteristics of tobacco leaves,cigarette smoke composition and the metabolic pathway.This study provided a new way to reduce and regulate tobacco nicotine content through agricultural measures selectively,and provided technical support and theoretical basis for the feasibility analysis of ultra-low nicotine content tobacco leaves production.