title: Knock-out of Arabidopsis AtNHX4 gene enhances tolerance to salt stress.
abstract: AtNHX4 belongs to the monovalent cation:proton antiporter-1 (CPA1) family in Arabidopsis. Several members of this family have been shown to be critical for plant responses to abiotic stress, but little is known on the biological functions of AtNHX4. Here, we provide the evidence that AtNHX4 plays important roles in Arabidopsis responses to salt stress. Expression of AtNHX4 was responsive to salt stress and abscisic acid. Experiments with CFP-AtNHX4 fusion protein indicated that AtNHX4 is vacuolar localized. The nhx4 mutant showed enhanced tolerance to salt stress, and lower Na(+) content under high NaCl stress compared with wild-type plants. Furthermore, heterologous expression of AtNHX4 in Escherichia coli BL21 rendered the transformants hypersensitive to NaCl. Deletion of the hydrophilic C-terminus of AtNHX4 dramatically increased the hypersensitivity of transformants, indicating that AtNHX4 may function in Na(+) homeostasis in plant cell, and its C-terminus plays a role in regulating the AtNHX4 activity.
authors.affiliation: Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
authors.forename: Hong-Tao
authors.initials: HT
authors.lastname: Li
authors.forename: Hua
authors.initials: H
authors.lastname: Liu
authors.forename: Xiao-Shu
authors.initials: XS
authors.lastname: Gao
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic; D012965:Sodium Chloride / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000235:genetics; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C540577:NHX4 protein, Arabidopsis; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride