The Physiological, Biochemical And Molecular Mechanism Of Mineral Elements Regulating Tobacco Resistant To PVY~N

The regulating action of mineral elements on tobacco plants for resistant to PVY^N was studied by using tobacco variety K326.The mineral elements can improve the tobacco resistant to PVY^N through promoting the physiological and biochemical property.The resistant molecular mechanism of tobacco regulated with mineral elements to PVY^N were revealed in this paper.1.Magnesium,iron,copper and boron can improve the tobacco resistant to PVY^N, which made the disease symptom lightened and the content of virus decreased at the best concentration of Mg 3(240 mg·L^-1),Fe4(33.6 mg·L^-1),Cu3(0.8 mg·L^-1) and B3(20 mg·L^-1). Effect on content of virus in tobacco which treated with different mineral elements at 24,72, 120,168 h showed that,the best induced time to tobacco treated with iron,magnesium and boron was 24 h,and that of copper treatment having no difference between 24,72 and 120 h. In a word,24 h was the best induced time to tobacco treated different elements.2.The Magnesium,iron,copper and boron can improve the tobacco resistant to PVY^N through promoting the physiological and biochemical property.The results showed that the activity of PAL,POD,CAT and the content of proline,soluble sugar,chlorophyll and lignin in tobacco leaves which inoculated with PVY^N after spraying mineral elements were increased,the content of leakage rate and MDA of electrolyte restrained.Those indicated that the induced resistance was promoted and the symptom was lightened.Furthermore,the production rate of activated oxygen raised sharply in a short time after treatment,those indicated that the induce resistance of tobacco was induced.Besides,the activity of PPO and content of total phenol and flavonoid,which closely linked to vein necrosis,were higher than those of the control in 12 days to resistant PVY^N,but much lower than those of the control when the vein necrosis came severity,which showed that the degree of vein browning was related to the PPO activity and the content of total phenol and flavonoid decreasing.In conclusion spraying iron can induce tobacco plant resistance to PVY^N.3.Content of salicylic acid and ethylene in tobacco were increased by spraying mineral elements.The results showed that the content of salicylic acid(SA) increased 1.3 times in 15th after treatment.The release of ethylene(ETH) was much higher than that of control in a short time.At the 12^th day,ETH released of control was sharply increased,which was much higher than that of copper treatment,because the signal pathway in tobacco leaves was activated when treated with copper solution in early time.But the symptom of control was seriously at later time,which is the factor of ETH released rose.In conclusion spraying copper solution can induce tobacco plant resistance to PVY^N and activate the signal pathway.4.The calcium system was regulated by changing of Ca2⁺ in tobacco treated with mineral elements,and the activity of CaM,PLC and PKC which related with signal transduction promoted.The effect of iron,copper and magnesium solution on the Calcium signal pathway had been preliminarily identified.Consequently,there has a close relative between the content of Ca²⁺ and Ca²⁺ -ATPase and NADKase activity in tobacco leaves. Compared with those of control treatments,the content of Ca²⁺ and total calcium was increased in different time,Ca²⁺ -ATPase and NADKase activated simultaneity.Through the method of ELISA,the activity of CaM and PKC in tobacco which treated with mineral elements was promoted in early time.But there has a a negative correlation between PLC and the content of Ca²⁺.So that the calcium signal pathway could adjust by mineral elements through altering the content of Ca²⁺.5.Take SYBR Green I as the intercalating fluorescence dye in Real-time PCR,the overexpression of WIPK and SIPK,which were the key genes of MAPK cascades,and the resistant gene PR1 in tobacco treated with copper and magnesium solution were studied.The results showed that,the expression of WIPK,SIPK and PR1 were appeared in tobacco of all treatment and control.But the amount of expression in tobacco treated with copper and magnesium solution were much higher than that of control.Except the expression levels of SIPK largest in the 96h,WIPK and PR1 expressions were both the largest in the 168h.So the key genes over expression of signal pathway in tobacco were induced by spraying copper and magnesium solution,the system resistance of tobacco to PVY^N appeared.