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The Influence Of AtHKT1;1or AtSOS1Mutation On The Expression Of Na~+or K~+Transporter Genes In Arabidopsis Thaliana Under Salt Stress

Posted on:2015-03-05Degree:MasterType:Thesis
Country:ChinaCandidate:C GuanFull Text:PDF
GTID:2250330431951211Subject:Lawn nutritional biology
Abstract/Summary:PDF Full Text Request
Plant growth under low K+availability or salt stress requires tight control of K+and Na+uptake, long-distance transport and accumulation. The family of membrane transporters named HKT (for High-Affinity K+Transporters), permeable either to K+and Na+or to Na+only, is thought to play main roles in these functions. Whereas Arabidopsis(Arabidopsis thaliana) possesses a single HKT transporter AtHKT1;1, involved in Na+transport in vascular tissues. While, the plasma membrane Na+/H+antiporter SOS1is thought to be involved in Na+efflux in plants, protect themselves from Na+toxicity and hence, salt tolerance. Changes in gene expression were compared during mild (25mM NaC1) or severe (100mM NaCl) salt stress among the wild type, a representative SOS1mutant, atsosl, a typical AtHKT1;1mutation, athkt1;1, and a athkt1;1-sosl double mutant by qRT-PCR. The main results were showed as follows:1. In Arabidopsis, the expression of AtSOSl might be inhibited by AtHKT1;1mutation, and the mutation in AtSOSl might suppress AtHKT1;1transcripts under salt stress, suggesting that the transporter genes AtHKT1;1and AtSOSl expressing in the xylem parenchyma cells possibly coordinate to keep the Na+and K+homeostasis.2. The down-regulation of AtHKT1;1possibly causes membrane hyperpolarisation of xylem parenchyma cells and restrains K+efflux into the xylem via AtSKOR. The decreased AtSKOR expression levels block the K+translocation toward the shoot, and the transcription of genes that mediate K+uptake, the inward-rectifying K+channel AtAKT1in particular, might be a feedback inhibition.3. In athkt1;1roots, expressing of the outward-rectifying K+channel AtSKOR was inhibited comparing to the WT, but the transcripts of K+transporter genes AtAKTl and AtHAK5were up-regulated under salt stress. Here we hypothesized that the channel AtAKT1or transporter AtHAK5, which previously mediated high-affinity K+uptake, possibly was the candidate of low-affinity Na+uptake when AtHKT1;1was silenced.Taken together, the plasma membrane Na+/H+antiporter SOSl plays an important role in regulating the uptake and transfer of K+or Na+in plants exposed to salt stress.
Keywords/Search Tags:Arabidopsis thaliana, atsos1, athkt1, 1, Na~+, K~+, qRT-PCR, mild salt stress, severe salt stress
PDF Full Text Request
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