| Potassium is one of the most important inorganic cations required for plant growth and metabolism,the absorption and utilization of potassium was widely distributed in various tissues of plant, in naturaland agricultural production. Potassium deficiency frequently limits plants growth because of the lowamount of soluble K that can be directly absorbed by plants, therefore, in order to adapt to the lack ofpotassium, maintain the potassium balance of the plant, plants have formed a number of adaptivemechanisms to respond to potassium deficiency in the long-term evolutionary process.Absorption and transportation of available potassium by plants from the external environment ismainly done through a variety affinity potassium transporter and channel protein and transcription factorwhich expressed in plant root cell membrance, so far, the study of potassium ion channel proteins andtransport proteins were deeply investigated in the model plant: Arabidopsis. Potassium is essentialelement for the soybean, but it’s little known about the related genes and function. In order to clarity thesoybean potassium transporter and channel protein expression patterns in the low potassium stressconditions and the stress gene function, two different potassium-tolerance varieties had been chosen andReal-time PCR had been used to screen the related response genes between the two varieties in thisstudy, we selected significant genes from potassium channel, potassium transporter, transcription factorto further research, bioinformatics technology had been utilized for related function. A green fluorescent(GFP)-tagged gene was fused genes to analysis their subcellular localization. Meanwhile, verified thefunctionality of these genes by transformation of Arabidopsis thaliana, and hoped to provide theoreticalbasis for transgenic soybean breeding. The results are as follows:1. Observing the response of different varieties under the low potassium stress, according tophenotype, related indexes of roots, the potassium tolerance variety You06-71and potassiumintolerance variety HC04-11have been checked.2. GmKT12was predicted as a potassium transporter which is of great importance in absorbingnutrients, signal transduction in plant growth progress. At present, there are few reports about thegene. In this paper, one low K tolerance soybean line You06-71and one low K intolerance lineHengchun04-11were chose as plant materials. In order to research the expression level of GmKT12in low potassium stress conditions, RNA was extracted and Real-time PCR was carried out in eightperiods. The results showed that there were highly significant differences between two lines, thereason of differences was diversity of amino acid sequence and protein structure between two lines.Homology and Bioinformatics analysis results after cloning the target sequencing from the twolines and sequencing demonstrated that comparing with GmKT12, there were56homologous genesof more than30percent similarity, GmKT12and Glyma18g18822were nearest in the phylogenetictree. The protein encoded by GmKT12was soluble transmembrane protein which contained11-12membrane structural domains, possessed multiple phosphorylation sites. These indicated that theprotein might take part in plant signal transduction and regulate potassium ions in and out of cells.In conclusion, GmKT12might play the pivotal role in potassium absorption in soybean and has important value in research.3. One low K tolerance soybean line You06-71and one low K susceptible line Hengchun04-11wereselected as plant materials. In order to study the expression level of GmKAB1in low potassiumstress condition, RNA was extracted and Real-time PCR was carried out in eight periods. Theresults showed that the relative expression levels of underground part were sustained longer ahigher than that of overground parts, underground parts of tolerance line were higher3.5times thansusceptible ones. The relative expression level of s susceptible parts were obviouslly higher thanoverground parts. Homology and bioinformatics analysis results after cloning the target sequencingindicated there were45homologous genes of more than30percent similarity, GmKAB1andGlyma20g19000were nearest in the phylogenetic tree. The protein encoded by GmKAB1was stableand soluble protein which contained two conversed structural domains, possessed multiplephosphorylation sites. These indicated that GmKABl polypeptide forms a tight physical associationwith β subunit and α subunit encoded by GmKABl to control voltage-gated K+channel. Inconclusion, GmKAB1might play the pivotal role in potassium absorption in soybean and hasimportant value in research.4. One low K tolerance soybean line You06-71and one low K intolerance line Hengchun04-11werechose as plant materials. In order to research the expression level of GmWRKY50in low potassiumstress conditions, RNA was extracted and Real-time PCR was carried out in eight periods. Theresults showed that the difference of underground relative gene expression level were moresignificant than overground parts between two lines, but the trend kept similar. Cloning the targetsequencing and transforming onion epidermal cells and arabidopsis, the result was that GmWRKY50expressed in onion epidermal cells that coincided with its function of transcription factor. Screenedand observed the phenotype diversity between positive seeding for T3genetrations and wild type,the consequence was that over-expression seeding grew better than WT not ever in control mediumbut in low potassium medium. Testing the potassium content of three over-expression Arabidopsislines and wide-type plants, the results displayed that there was no obvious difference betweenover-expression and WT lines when the plants were cultivated in normal medium, but the potassiumcontent of over-expression lines was significantly higher than WT plants in low-potassium medium,which illustrated that GmWRKY50would be expressed highly to regulated downstream genesexpression and compete more nutrient when plants growed normally or suffered low potassiumstress. |
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