title: Soil bacteria confer plant salt tolerance by tissue-specific regulation of the sodium transporter HKT1.
abstract: Elevated sodium (Na(+)) decreases plant growth and, thereby, agricultural productivity. The ion transporter high-affinity K(+) transporter (HKT)1 controls Na(+) import in roots, yet dysfunction or overexpression of HKT1 fails to increase salt tolerance, raising questions as to HKT1's role in regulating Na(+) homeostasis. Here, we report that tissue-specific regulation of HKT1 by the soil bacterium Bacillus subtilis GB03 confers salt tolerance in Arabidopsis thaliana. Under salt stress (100 mM NaCl), GB03 concurrently down- and upregulates HKT1 expression in roots and shoots, respectively, resulting in lower Na(+) accumulation throughout the plant compared with controls. Consistent with HKT1 participation in GB03-induced salt tolerance, GB03 fails to rescue salt-stressed athkt1 mutants from stunted foliar growth and elevated total Na(+) whereas salt-stressed Na(+) export mutants sos3 show GB03-induced salt tolerance with enhanced shoot and root growth as well as reduced total Na(+). These results demonstrate that tissue-specific regulation of HKT1 is critical for managing Na(+) homeostasis in salt-stressed plants, as well as underscore the breadth and sophistication of plant-microbe interactions.
authors.affiliation: Texas Tech University, Department of Chemistry, Biochemistry and Biology Lubbock 79409, U.S.A.
authors.forename: Huiming
authors.initials: H
authors.lastname: Zhang
authors.forename: Mi-Seong
authors.initials: MS
authors.lastname: Kim
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Scot E
authors.initials: SE
authors.lastname: Dowd
authors.forename: Huazhong
authors.initials: H
authors.lastname: Shi
authors.forename: Paul W
authors.initials: PW
authors.lastname: Paré
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001412:Bacillus subtilis / Q000502:physiology*; D001692:Biological Transport; D027682:Cation Transport Proteins / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006706:Homeostasis; D054884:Host-Pathogen Interactions; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000382:microbiology / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D012988:Soil Microbiology; D027981:Symporters / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C490286:HKT1 protein, Arabidopsis; D027981:Symporters; D012965:Sodium Chloride; D012964:Sodium