Functions Of Arabidopsis Potassium Channel AKT1 In Stress Resistance And Development

Potassium(K)is one of the three major nutrients essential for plant growth and development,and can participate in the regulation of enzyme activity,membrane potential,cell homeostasis and protein stable synthesis.A large number of studies have shown that plants absorb potassium ions from the outside mainly through potassium ion channels and transporter proteins.A number of potassium channels and transporters have been reported in the model plant Arabidopsis,of which AKT1(Arabidopsis K~+transporer 1)has been studied more,but there are still many physiological functions to be further studied.Studies have shown that CBL1(Calcineurin B-like protein 1)/CBL9(Calcineurin B-like protein 9)interacts with CIPK23(CBL-Interacting Protein Kinase 23)on the plasma membrane to activate potassium channel AKT1 by phosphorylation.Thereby regulating the absorption of potassium ions by plants.In this paper,Arabidopsis thaliana was used as research material to study the role of Arabidopsis potassium channel AKT1 and CBL9 and CIPK23 in plant growth and disease resistance.The function of potassium channel AKT1 in Arabidopsis thaliana to control drought,high salt and low temperature against abiotic stress was also studied.The main findings of this paper are as follows:1.AKT1,CBL9 and CIPK23 are involved in the regulation of plant growth and development,including leaf size,plant size and flowering time.The three mutant plants akt1,cbl9 and cipk23 have distinct leaf and plant type phenotypes,and the akt1 mutant has the smallest leaf and plant type.These three mutant plants have a distinct late flower phenotype under long-day conditions.Their florescence positive regulators FT and SCO1 transcription levels were significantly inhibited,while the floral negative regulator FLC transcription levels were increased.2.AKT1,CBL9 and CIPK23 regulate plant disease resistance.After inoculation of the pathogenic bacteria Pseudomonas syringae pv.tomato DC3000 and Pseudomonas syringae pv.maculicola ES4326 on the three mutations akt1,cbl9 and cipk23,the statistics of the symptoms and colonies and the transcriptional level of the disease-associated genes proved AKT1,CBL9 and CIPK23.It is regulating the resistance of plants to this type of pathogenic bacteria.At the same time,this study also found that AKT1,CBL9 and CIPK23 positively regulate the resistance of plants to Botrytis cinerea.These three mutants showed a serious susceptibility phenotype after inoculation with Botrytis cinerea,mortality,lesion diameter,pathogen.The biomass was greater than the wild type.3.AKT1 and CBL9 and CIPK23 are capable of regulating pathogen-associated molecular patterns(flagellin and chitin)-induced immune responses(PAMP-triggered immunity,PTI).4.AKT1 negatively regulates the drought resistance of plants.The akt1 mutant showed a distinct drought-resistant phenotype.The water loss rate of akt1 mutant was significantly lower than that of wild type,and the survival rate was higher than that of wild type.The expression level of stress-related genes was higher than that of wild type.5.Under high salt stress,the seed germination rate,survival rate and transcriptional level of stress-related genes of akt1 mutant were higher than wild type.Therefore,the sensitivity of the akt1 mutant to salt is weakened,and the salt tolerance of the plant is enhanced.6.The akt1 mutant is more resistant to low temperature stress than wild-type.The above results indicate that potassium channel AKT1 and CBL9 and CIPK23 can regulate plant leaf and plant type size,flowering time,and resistance to Pseudomonas syringae pathogen and Botrytis cinerea dead body nutrient pathogen.The study concluded that AKT1 and CBL9 and CIPK23 can positively regulate plant growth and development;AKT1 and CBL9 and CIPK23 can positively regulate plant resistance to Pseudomonas syringae and Botrytis cinerea;AKT1 can negatively regulate plant drought,high salt and low temperature stress.