title: The Tomato 14-3-3 protein TFT4 modulates H+ efflux, basipetal auxin transport, and the PKS5-J3 pathway in the root growth response to alkaline stress.
abstract: Alkaline stress is a common environmental stress, in particular in salinized soils. Plant roots respond to a variety of soil stresses by regulating their growth, but the nature of the regulatory pathways engaged in the alkaline stress response (ASR) is not yet understood. Previous studies show that PIN-FORMED2, an auxin (indole-3-acetic acid [IAA]) efflux transporter, PKS5, a protein kinase, and DNAJ HOMOLOG3 (J3), a chaperone, play key roles in root H(+) secretion by regulating plasma membrane (PM) H(+)-ATPases directly or by targeting 14-3-3 proteins. Here, we investigated the expression of all 14-3-3 gene family members (TOMATO 14-3-3 PROTEIN1 [TFT1]-TFT12) in tomato (Solanum lycopersicum) under ASR, showing the involvement of four of them, TFT1, TFT4, TFT6, and TFT7. When these genes were separately introduced into Arabidopsis (Arabidopsis thaliana) and overexpressed, only the growth of TFT4 overexpressors was significantly enhanced when compared with the wild type under stress. H(+) efflux and the activity of PM H(+)-ATPase were significantly enhanced in the root tips of TFT4 overexpressors. Microarray analysis and pharmacological examination of the overexpressor and mutant plants revealed that overexpression of TFT4 maintains primary root elongation by modulating PM H(+)-ATPase-mediated H(+) efflux and basipetal IAA transport in root tips under alkaline stress. TFT4 further plays important roles in the PKS5-J3 signaling pathway. Our study demonstrates that TFT4 acts as a regulator in the integration of H(+) efflux, basipetal IAA transport, and the PKS5-J3 pathway in the ASR of roots and coordinates root apex responses to alkaline stress for the maintenance of primary root elongation.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Xu
authors.forename: Liguo
authors.initials: L
authors.lastname: Jia
authors.forename: Weiming
authors.initials: W
authors.lastname: Shi
authors.forename: Frantisek
authors.initials: F
authors.lastname: Baluska
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Kronzucker
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Liang
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000468:Alkalies / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects; D018533:Biomass; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D018519:Meristem / Q000187:drug effects / Q000201:enzymology; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011522:Protons; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D048948:14-3-3 Proteins; D000468:Alkalies; D007210:Indoleacetic Acids; D010940:Plant Proteins; D011522:Protons; D006180:Proton-Translocating ATPases