Identification For Salt-related Function Of Plant Potassium Transporter Genes (HcKUP12 And AtKUP12) From Halostachys Caspica And Arabidopsis Thaliana

As the largest family of the high-affinity potassium transport system in plants,HAK/KUP/KT plays an important role in plant potassium uptake,distribution,and homeostasis.It also contributes to plant growth and survival under salt stress and other abiotic stresses.In this study,Arabidopsis thaliana AtKUP12 andHalostachys caspica HcKUP12,which are members of the same III cluster of HAK/KUP/KT family,as subjects were used to research their functions.By measuring the Na~+,K~+content and root length and phenotype of transgenic Arabidopsis thaliana under low potassium and high salt stress,potassium transport and salt tolerance functions of transporter KUP12 from glycophyte and halophytes were analyzed.The major experimental results are as follows:(1)The atkup12 mutant Arabidopsis pure line plants with inactivated T-DNA insertion of Arabidopsis thaliana AtKUP12 gene were identified by antibiotic screening and reverse transcription RT-PCR.The phenotype,root length,fresh weight,and potassium content of wild-type Arabidopsis thaliana WT,atkup12 mutant,and AtKUP12 complement mutant Arabidopsis seedlings under low potassium were measured.The results showed that:Comparing with wild-type and AtKUP12complement mutant Arabidopsis,the atkup12 mutant had the lowest root length,fresh weight,and ion content,followed by At KUP12 functional replenishing plants,and wild-type plants was the best.It is suggested that Arabidopsis AtKUP12 is involved in the high-affinity uptaking of K~+when the Arabidopsis thaliana under low potassium,which promotes plant growth accordingly.At the same time,the root length,fresh weight,Na~+,K~+content and K~+/Na~+of the above three plant seedlings under different salt stress conditions were measured.The results were basically consistent with low potassium stress.It was speculated that AtKUP12 may promote plant Potassium absorption under salt stress,thus increasing the K~+/Na~+of the plant under stress,and affecting the plant's tolerance to salt stress(2)The heterologous expression of the HcKUP12 gene of Halostachys caspica Arabidopsis strain OE4 and OE21 lines with the wild type were used to determine the root length,fresh weight and ion content of the Arabidopsis under low potassium and salt stress.The function of the Halostachys caspica HcKUP12 transporter is response to low potassium and salt stress.Under low potassium stress of 50?mol/L,the root length,fresh weight,and potassium content of transgenic HcKUP12 Arabidopsis were significantly higher than those of wild-type plants;the roots of OE4 and OE21overexpressing plants under 100 and 125 mmol/L NaCl stress.The length was significantly higher than that of the wild type plants;although the fresh weight of the heterologously expressed plants was higher than that of the wild type control,there was no significant difference between the two.At 125 mmol/L NaCl concentration,there was no difference in Na~+content between the over-expressed strains OE4 and OE21 and wild-type plants,but the K~+content and K~+/Na~+ratio were significantly higher than those in the wild-type control group.(3)At the same time,we also successfully constructed a yeast expression vector for Arabidopsis AtKUP12 and Halostachys Caspica HcKUP12 genes,and we intend to further compare and analyze the two Potassium transport and salt tolerance of KUP12 transporters,which are translocations from different sources and locations by transforming the potassium ion-absorption-deficient yeast CY162.