Research On The Relationship Between SOS Signaling Pathways And K~+ Absorption And Nutrition Absorption Related Gene TGA4 Cloning

The organism is a complex network systerm,intracellular physiological regulatory processes are closely linked.The absorption of nutrients not only can provide adequate nutrients for plant,but also improve plant resistance through the absorption and transportation of nutrients.Clonging the genes which can increase the absorption of nutrients and enhance stress resistance and analysing gene function and mechanism which has important significance for the absorption and resistance of plant.Obtaining transgenic plants through genetic engineering can improve the ability of plants to absorb nutrients and resist drought and other abiotic stresses.Studies have shown that TGA4 gene which belongs to bZIP transcription factor family can respond the stimulation of NO and enhance the transcription of downstream genes,meanwhile,bZIP transcription factor family play an important role in drought resistance.In this thesis,the function in nitrogen uptake and drought resistance of TGA4 has been researched.The results show that:1)the results of expression nanlysis show that TGA4 gene expression is induced under drought and nitrogen stress conditions.2)We obtain 11 transgenic lines,wild-type Arabidopsis thaliana and transgenic plants were treated under drought and low nitrogen condition.Observing and identifying plant phenotype and physiological indicators during different growth stages,the results showed that the transgenic Arabidopsis growing better than WT under drought conditions,the drought resistance physiological indicators also significantly better than WT;under the low nitrogen conditions,transgenic Arabidopsis absorb more nitrogen compared with WT.3)In order to further understand the relationship between the two functions of TGA4 gene,We treated mutants、WT and transgenic Arabidopsis under drought conditions and determinate the glutamine synthetase activity,total nitrogen,nitrate reductase activity and analyse the expression differences of NRT1.1、NRT2.1、NRT2.2、NRT2.5、NIA1、NIA2、GLN1.4、G-6-PD2,the results show that under drought condition,the expression of NRT2.1、NRT2.2、NIA1、NIA2 higher than WT and the expression of TGA4 gene can influence plant nitrogen uptake and transporter.According to the above results,we speculate that TGA4 gene can improve the ability of drought resistance through improving nitrogen absorption.The results show that:1)Some research have shown that the increase of K⁺/Na⁺ratio in vacuole can alleviate growth inhibition caused by salt stress,in order to understand the relationship between the plant potassium ion absorption and high salt stress,We use sos1、sos2、sos3 and WT as experimental material and analyse the alteration of K⁺uptake between Mutants,We use sos1、sos2、sos3 and WT as experimental material which are treated on the medium which contain different Na⁺/K⁺ ratio.We compared phenotype differences and scanned root and determined GRG and Na⁺/K⁺ratio,and the difference between K⁺transporters AKT1、AKT2、SKOR are analyzed by RT-PCR method.The result showed that when the concentration of external K⁺is less than 110 mmol·L^-1,the increase concentration of K⁺ can alleviate inhibitory effect caused by salt stress,but SOS signals pathway did not regulate K⁺absorption and transportation directly.2)When WT and mutants were treated on low concentration of NaCl we found that sos3 had significant different compared with sosl and sos2,the result indicate that there may be another protein which has the similar function with SOS3 can sense the external salt signal and transmit this signal to SOS2.