Study On Signal Compounds Induced Nicotine Accumulation Of Flue-Cured Tobacco After Topping

Pot and solution culture experiments were conducted with K326 from 2005 to 2006 to study the relationship between nicotine synthesis and change of source-sink relation of flue-cured tobacco which treated with non-topping(T1)and topping(after transplantation 61d,T2),and the relationship between the intensity of nicotine synthesis strengthened and the relation of source-sink changed was tested by non-topping of the upper leaves doodle JA(T3)which was the treatment of changing source-sink relation.The substance of signal long distance conduction was chosen, and which was tested by solution culture experiments.Which were conducted in Henan Agricultural University and Key Discipline and Henan Key Laboratory for Regulating and Controlling Cop Growth and Development.The results were as follows:1.The relation of source-sink in tobacco plants growth and development changed by topping through the changes of carbon and nitrogen metabolism intensity analyzed before and after topping.The changes of carbon metabolism intensity:the activity of invertase in upper leaves and root system of T2(topping)and T3(non-topping of the upper leaves doodle JA)reached maximum after transplantation 62d,subsequently the activity of invertase in upper leaves dropped to lower than the control(T1)level,but which in root system was higher than that of T1.The content of soluble sugar in upper leaves of T2 and T3 had been decreased after transplantation 61d,which in root system increased and reached maximum after transplantation 64d.The content of sucrose in upper leaves,tissues outside tobacco stalk cambium(phloem)and root system of increased after transplantation 61d,and reached maximum after transplantation 64d, but the level of which in root system increased was relatively high.The fructose content in upper leaves of T2 and T3 reached maximum after transplantation 62d, then dropped to lower than T1,which in root system reached maximum after transplantation 64d,then decreased but was higher than T1 after transplantation 66d.The changes of nitrogen metabolism intensity:The activity of GS in upper leaves of T2 and T3 decreased after transplantation 61d then increased continually,which in root system had been increased and the level was higher than that in upper leaves.The contents of free amino acids,nitrate and ammonium in upper leaves and root system of T2 and T3 increased and reached maximum after transplantation 64d,then decreased but was higher than T1 after transplantation 66d.The content of nicotine in upper leaves of increased continually after transplantation 61d,which in tissues inside tobacco stalk cambium(xylem)and root system reached maximum after transplantation 64d,then decreased.All these showed that the intensity of carbon and nitrogen metabolism strengthened in root system because massive carbon and nitrogen compounds transported to root system after topping.The fructose content increased remarkably in root system,whose increase tendency is same as nicotine content in root system. The change tendency of carbon and nitrogen metabolism intensity of T3 and T2 was same,but the intensity was obviously lower than T2,which showed that the change of source-sink relation was one of the main reasons in the intensity of nicotine synthesis strengthened,but also existed other regulative factors.2.The change of related enzyme protein of nicotine synthesis in root systemThe enzyme protein in root system of T2 and T3 were detected by nucleic acid protein detector,the figure column chromatography showed that the peak height and area reached maximum after transplantation 64d.The protein expression of T2 and T3 was increased,and specific band appeared after transplantation 64d by SDS-PAGE.All these showed that the related enzyme protein expression of nicotine synthesis in root system increased,the specific band indicated that there was new protein expressed.3.The expression of protein group in root point organizationThe special protein spots in T2 and T3 expressed lowly but in T1 highly,which was examined by the bidirectional electricity swims.Carded on the MALDI-TOF-MS peptide quality fingerprint atlas analysis and retrieved with Mascot software in the NCBInr database,the spot was:Sorbitol -6 phosphoric acid dehydrogenase.The reason of fructose content increased was confirmed and explained by this molecular level result.The Sorbitol -6 phosphoric acid dehydrogenase expressed highly,and the activity was high before topping,which caused 6-phosphoric acid fructose transferred to 6-phosphoric acid sorbitol.The 6-phosphoric acid fructose in plants has two transfer sides,The Sorbitol -6 phosphoric acid dehydrogenase expressed lowly,and the activity was low after topping,which caused 6-phosphoric acid fructose transferred to 3- phosphoglyceraldehyde,and more nicotine was synthesized.4.Fructose as the substance of signal long distance conduction regulated the intensity of nicotine synthesis.The nicotine content in upper leaves of T3 was 1.1 times as much as T1 at the fifth after topping,which of T4 was 2.7 times as much as T2.The nicotine content in root system of T3 was 1.3 times as much as T1 at the third after topping,which of T4 was 1.5 times as much as T2.The results showed that fructose was a signal substance controlled root nicotine synthesis.