title: Arabidopsis Pht1;5 mobilizes phosphate between source and sink organs and influences the interaction between phosphate homeostasis and ethylene signaling.
abstract: Phosphorus (P) remobilization in plants is required for continuous growth and development. The Arabidopsis (Arabidopsis thaliana) inorganic phosphate (Pi) transporter Pht1;5 has been implicated in mobilizing stored Pi out of older leaves. In this study, we used a reverse genetics approach to study the role of Pht1;5 in Pi homeostasis. Under low-Pi conditions, Pht1;5 loss of function (pht1;5-1) resulted in reduced P allocation to shoots and elevated transcript levels for several Pi starvation-response genes. Under Pi-replete conditions, pht1;5-1 had higher shoot P content compared with the wild type but had reduced P content in roots. Constitutive overexpression of Pht1;5 had the opposite effect on P distribution: namely, lower P levels in shoots compared with the wild type but higher P content in roots. Pht1;5 overexpression also resulted in altered Pi remobilization, as evidenced by a greater than 2-fold increase in the accumulation of Pi in siliques, premature senescence, and an increase in transcript levels of genes involved in Pi scavenging. Furthermore, Pht1;5 overexpressors exhibited increased root hair formation and reduced primary root growth that could be rescued by the application of silver nitrate (ethylene perception inhibitor) or aminoethoxyvinylglycine (ethylene biosynthesis inhibitor), respectively. Together, these data indicate that Pht1;5 plays a critical role in mobilizing Pi from P source to sink organs in accordance with developmental cues and P status. The study also provides evidence for a link between Pi and ethylene signaling pathways.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Vinay K
authors.initials: VK
authors.lastname: Nagarajan
authors.forename: Ajay
authors.initials: A
authors.lastname: Jain
authors.forename: Michael D
authors.initials: MD
authors.lastname: Poling
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Lewis
authors.forename: Kashchandra G
authors.initials: KG
authors.lastname: Raghothama
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Smith
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001149:Arsenates / Q000633:toxicity; D018533:Biomass; D004269:DNA, Bacterial / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D001149:Arsenates; D004269:DNA, Bacterial; D005030:Ethylenes; D028061:Phosphate Transport Proteins; D010710:Phosphates; C561918:Pht1;5 protein, Arabidopsis; C036483:T-DNA; C036216:ethylene; C025657:arsenic acid