Molecular Plant Advance Access originally published online on March 27, 2009
Molecular Plant 2009 2(3):535-552; doi:10.1093/mp/ssp013
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The Phosphate Transporter PHT4;6 Is a Determinant of Salt Tolerance that Is Localized to the Golgi Apparatus of Arabidopsis
a Instituto de Recursos Naturales y Agrobiologia, Consejo Superior de Investigaciones Cientificas, Avda Reina Mercedes 10, Sevilla-41012, Spain
b Center for Environmental Stress Physiology, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-2010, USA
c Present address: Ichinoseki National College of Technology, Department of Chemical Engineering, Takanashi, Hagisyo, Ichinoseki 021-8511, Japan
d Present address: Graduate School of Life and Environmental Sciences, Gene Research Center 220, 1-1-1 Ten-nou dai, University of Tsukuba, Tsukuba 305-8572, Japan
1 To whom correspondence should be addressed. E-mail pardo{at}cica.es, fax (34)954624002, tel. (34)954624711 ext 168.
Insertion mutations that disrupt the function of PHT4;6 (At5g44370) cause NaCl hypersensitivity of Arabidopsis seedlings that is characterized by reduced growth of the primary root, enhanced lateral branching, and swelling of root tips. Mutant phenotypes were exacerbated by sucrose, but not by equiosmolar concentrations of mannitol, and attenuated by low inorganic phosphate in the medium. Protein PHT4;6 belongs to the Major Facilitator Superfamily of permeases that shares significant sequence similarity to mammalian type-I Pi transporters and vesicular glutamate transporters, and is a member of the PHT4 family of putative intracellular phosphate transporters of plants. PHT4;6 localizes to the Golgi membrane and transport studies indicate that PHT4;6 facilitates the selective transport of Pi but not of chloride or inorganic anions. Phenotypic similarities with other mutants displaying root swelling suggest that PHT4;6 likely functions in protein N-glycosylation and cell wall biosynthesis, which are essential for salt tolerance. Together, our results indicate that PHT4;6 transports Pi out of the Golgi lumenal space for the re-cycling of the Pi released from glycosylation processes.
Key Words: Phosphate transport • Golgi • glycosylation • salt stress
2 These authors contributed equally to this work and are listed in alphabetical order.
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