Research Of Cleavage Of Tobacco Carotenoid About Physiology And Adjusting Mechanism

Tobacco is one of the important economic crops in China.The quality of tobacco leaf is determined by the quality of appearance and aroma.The content of carotenoid has significant influence on tobacco appearance quality.As carotenoid cleavage product has low threshold,small excitant and good aroma and has the effect that reduces irritation and mellows smoke,it is one of the important influencing factors of the quality of tobacco aroma.The paper researched on metabolism of tobacco carotenoid and adjusting mechanism.It also analyzed the reason of carotenoid cleavage differences between varieties and the relationship with the content of cleavage product.It was intended to provide theoretical help on breeding work and control technology for the purpose of improving the quality of the tobacco aroma.1 The relationship of carotenoid cleavage of different breeds and its product By studying different varieties carotenoid metabolic regularity,the relationship of the quantity of carotenoid cleavage and its product content was analyzed,analyzing the relationship of carotenoid cleavage with the appearance quality of the tobacco leaf and smoking evaluation.The results showed in the leaf age 20 to 30 d the content of flue-cured tobacco leaf after peak began to drop and the maximum accumulation existed difference between varieties.After leaf age 20 to 30 d the carotenoid content decreased gradually,and to harvest in leaf age 60 d degradation rate increased gradually.With higher carotenoid content variety in leaf age 60 d had higher carotenoid content after baking.During the period of growth and baking there were great differences of the amount on different varieties carotenoid cleavage.Carotenoid cleavage product accumulation was given priority to leaf growth period,and a significant difference was found in different varieties.In components of carotenoid cleavage product the content of ?-damascenone was higher,followed by farnesylacetone,four isomers of megastigmatrienone,geranylacetone,?-ionone and dihydroactinidiolide.Among different varieties both carotenoid cleavage product content and components content had differences.Breed of great cleavage had high ratio of yellow flue-tobacco leaf and in Smoking results had high index of smoking aroma quality,smoking aroma quality and concentration.Amount of aroma and primary components had significant or extremely significant positive correlation of the amount of carotenoid cleavage at growth and baking period and total cleavage.There was significant or extremely significant positive correlation of amount of aroma and primary components with the amount of carotenoid cleavage at growth and baking period and total cleavage.Promoting carotenoid cleavage,especially at growing,choosing a large quantity of carotenoid cleavage of varieties,was conducive to enhance the quality of the appearance of the tobacco leaf and aroma.2 The physiological processes of different varieties of carotenoid and respond to high temperature and lightBy 4 treatments high temperature and strong light,high temperature and medium light,medium temperature and high light,medium temperature and light,metabolic rules of carotenoid pigment composition content was researched.It also researched stability of pigment protein complexes,photosynthesis and fluorescence properties,active oxygen content and antioxidant capacity,maturity of tobacco leaves and the changes of the ultrastructure of cells and carotenoid cleavage dioxygenases and content of carotenoid cleavage product difference in varieties and response to the different light and temperature.The results showed breed with high carotenoids cleavage had low stability of pigment protein complexes,high nitrogen nutrition degradation,weak antioxidant capacity and high carotenoid cleavage dioxygenases activity.Related parameters of carotenoid metabolic had significant differences among varieties.In treatment of high temperature and light the contentof chromoprotein and soluble protein declined.Photosynthesis declined and photosyntheticmechanism of photosynthetic efficiency was low.Superoxide radicals and H2O2 had high accumulation while the activity of SOD and LOX was low and low active oxygen scavengering ability.They promoted cell aging and reduced thylakoid lamella.The amount of free carotenoids was high and CCD had high relatively expression.Tobacco thylakoid membrane protein degradation and destruction of thylakoid membrane were main influencing factors of carotenoid cleavage.The content of carotenoid cleavage at growth period and total cleavage(sum of growth and baking)in treatment of high temperature and light was great,followed by high temperature and medium light and medium temperature and light was low.Varieties and wide temperature had higher contribution rate of carotenoid cleavage,followed by light intensity.It turned out that closely associated with carotenoid metabolism was related indicators of tobacco growth and content of carotenoid cleavage and cleavage product.It was connected with stability of pigment protein,aging speed and degree of aging and activity of carotenoid cleavage dioxygenases.High temperature and strong light is contributing factor to carotenoid cleavage and accumulation of carotenoid cleavage product.3 Proteomic analysis of tobacco leaf with different light and temperature treatmentsTobacco leaf with different temperature and light treatment were analyzed by label free and got 3,274 differential protein spots.This paper had function analysis on significant difference protein.The results showed that comparing the differences of differential proteins in treatment of high light and high temperature and the treatment of medium light and medium temperature,differential proteins related to chloroplast or photosynthesis and process endoplasmic reticulum.They participated in the ion binding,polymer and part of the organelles metabolism in the cell and the processes of antioxidant system and carotenoid metabolism.They had different spots on biological process,molecular function and cell composition.The differential proteins main manifestation among varieties were chloroplast or photosynthesis,binding protein synthesis of endoplasmic reticulum antioxidant system and carotenoid metabolism besides including the process of resistance and cell death.It said in the aspect of proteomics among treatments and varieties existed differences and these different spots had similar with the different spots of physiological metabolism of carotenoid.4 Effects of nitrogen metabolism of tobacco leaf on carotenoid cleavage among varietiesBy setting the three levels of nitrogen treatment,the difference among varieties on tobacco leaf carotenoid accumulation and cleavage and aging and developing cleavage product resulted from nitrogen metabolism was analyzed.The results showed the degradation and distribution of tobacco leaf nitrogen nutrition existed significant difference among varieties according to the difference on degradation of soluble protein and total nitrogen,nitrogen metabolism related enzyme activity,especially the changing rule of the GS activity,ammonia compensation point and ammonia volatilization.The maximum number of accumulation and degradation of carotenoid in Yuyan 10 leaf magnified with the increasing of nitrogen application,while in NC89 the highest was in medium nitrogen.There were differences among varieties.Yuyan10 had strong nitrogen resistance because of response to the accumulation of nitrogen by volatilization to transfer again,while NC89 through resynthesis.Even under the condition of high nitrogen Yuyan10 could keep aging faster speed and higher degree.It had some expressions as followed Large amount of nitrogen nutrient degradation,higher Accumulation of ammonium concentration in leaf,large amount of ammonia volatilization low antioxidant enzyme activity,high lipoxygenase activity,large CCD relative expression amount.In different nitrogen application Yuyan10 was different from NC89.When carotenoid had high biggest accumulation and great cleavage,carotenoid cleavage product was high.So it should be based on nitrogen metabolism and aging characteristics of varieties and choose the appropriate nitrogen application to help carotenoid cleavage and product accumulation.5 Effects of maturity grade on leaf senescence and carotenoid cleavage among varietiesBy setting four different maturity,the difference among varieties on tobacco leaf carotenoid accumulation and cleavage and aging and developing cleavage product resulted from different maturity.The results showed the content of carotenoid in tobacco leaf continued declined with incresing maturity.NC89 had remarkable higher carotenoid than Yuyan 10 while Yuyan 10 had more cleavage.Yuyan 10 had rapid degradation of total nitrogen and soluble protein,low autioxidant enzyme activities,high membrane lipid peroxide level,strong medium resistance.It had fast aging and its carotenoid cleavage was high even at immature.Appropriate delay recovery improved the content of total sugar and reducibility sugar,nitrogen nutrition also constantly degradation and chemical composition being coordination.When harvested too late the quality was reduced.The amount of carotenoid cleavage and the main components is higher when harvested maturity after 5 d.Yuyan 10 had fast aging at earlier stage and sensitive to aging at later period which differed from NC89.So choose the suitable harvesting time should Comprehensive consider metabolism characteristics,the aging degree of maturity,The content of nutrients,Medium resistance of tobacco leaf to help carotenoid cleavage and product accumulation.6 Effects of allogenic material on carotenoid cleavage and cleavage product formed among varietiesBy spraying six different exogenous substances which had great influence of carotenoid metabolism,the difference among varieties on tobacco leaf carotenoid accumulation and cleavage and aging and developing cleavage product resulted from different six different exogenous substances.The results showed the content of carotenoid and the formation of degradation product existed differences among varieties on the response of exogenous substances.Salicylic acid enhanced carotenoid content,reducing aging degree and carotenoid degradation product.Abscisic acid and dithiothreitol reduced carotenoid content,promoting the formation of degradation product.Lutein and ?-carotene improved the carotenoid content and improved its degradation product content and the component of degradation product also was affected.With high aging degree Yuyan 10 had higher increased extent of carotenoid degradation product in the treatment of lutein and ?-carotene.NC89 with low aging degree had higher increased extent in the treatment of abscisic acid and dithiothreitol.Though GS suppressant increased tobacco leaf aging degree,it also inhibited the enzyme activity and the metabolism of plants with little contribution to the increase of the aroma components.Exogenous substances had an effect on promoting carotenoid degradation and product accumulation.The effect had differences among varieties and closely related to the metabolism of the material itself.The degradation of carotenoid and the formation of aroma established on combined action of Tobacco leaf aging degree Related metabolic enzyme activity.