Cloning of MhHAK5 Gene from Malus halliana and Identification of Its Low Potassium Tolerance Function

Ma Cuixia; Wu Xiangkai

doi:10.14083/j.issn.1001-4942.2025.06.003

Abstract：Potassium(K)is one of the essential mineral elements for plant growth and development,which is very important for yield and quality formation.HAK5 is an important high-affinity K transporter gene,which mainly mediates K uptake under low K conditions.However,little is known about the functional role of HAK5 in Malus.In this study,Malus halliana was used as experimental material,and its HAK5(MhHAK5)gene was cloned and analyzed.The physicochemical properties and tissue expression specificity were analyzed by bioinformatics analysis,and the response to low K was studied through overexpressing MhHAK5 in Arabi-dopsis thaliana by genetic transformation.The results showed that the full length of MhHAK5 gene was 1 830 bp with the open reading frame(ORF)as 1 695 bp,and it encoded 518 amino acids.The MhHAK5 protein had the molecular weight of 60.05 kDa and the isoelectric point of 7.45,had four transmembrane structures,was an unstable hydrophilic transmembrane protein,and was located in nucleus.Phylogenetic analysis showed that MhHAK5 had the highest similarity with AtHAK5,AtHAK10 in Arabidopsis thaliana and OsHAK5 in rice.Furthermore,it had Ser-Gly-Gly-Gly amino acid sequence.The results of tissue expression specificity a-nalysis showed that MhHAK5 had the highest expression level in roots of M.halliana,and was induced by low potassium.Compared with wild type(WT),overexpression of MhHAK5 could effectively improve K+absorp-tion and growth-promoting plant hormone synthesis of Arabidopsis plants under low K conditions,thus ensuring root development.In summary,MhHAK5 played an important role in response to K deficiency stress.The re-sults of this study could provide theoretical bases for gene improvement and breeding of K deficiency tolerant apple rootstocks.